carpological analysis of phoenix (arecaceae...

Carpological analysis of Phoenix (Arecaceae):contributions to the taxonomy and evolutionary historyof the genus

DIEGO RIVERA FLS1*, CONCEPCIÓN OBÓN FLS2, JOAQUÍN GARCÍA-ARTEAGA2,TERESA EGEA2, FRANCISCO ALCARAZ1, EMILIO LAGUNA3, ENCARNA CARREÑO1,DENNIS JOHNSON4, ROBERT KRUEGER5, JOSÉ DELGADILLO6 and SEGUNDO RÍOS7

1Depto. Biología Vegetal, Fac. Biología, Universidad de Murcia, 30100 Murcia, Spain2Depto. De Biología Aplicada, Escuela Politécnica Superior de Orihuela. Ctra. Beniel, Km 3,2.Universidad Miguel Hernández, 03312 Orihuela, Alicante, Spain3Generalitat Valenciana. Conselleria d’Infraestructures, Territori i Medi Ambient. Servei de VidaSilvestre/Centre per a la Investigació i Experimentació Forestal. Avda. Comarques del País Valencià,114. 46930 Quart de Poblet. València, Spain43726 Middlebrook Ave, Cincinnati, OH 45208, USA5National Clonal Germplasm Repository for Citrus and Dates, Riverside, 1060 Martin Luther KingBlvd, Riverside, CA 92507-5437, USA6Facultad de Ciencias, Campus de Ensenada, Universidad de Baja California, Ensenada, BajaCalifornia ZP 22830, Mexico7CIBIO, Universidad de Alicante, Alicante, Spain

Received 23 July 2013; revised 17 November 2013; accepted for publication 23 February 2014

The main purpose of this study was, first, to analyse the morphology of seeds of Phoenix spp. and relevant cultivarsand to assess the taxonomic value of the information generated as a means of studying the systematics andevolutionary history of the genus Phoenix. We then analysed seed morphological diversity in P. dactylifera,supported by morphotypes shared with fossil and/or archaeological materials, to advance the knowledge of theorigins, history and biogeography of one of the most important cultivated palm species. The other objective was todevelop a methodology for assigning different commercial seed samples and archaeological materials to determinedmorphotypes as a tool for their identification at the species level. Three hundred and sixty-four seed samples (3920seeds) were analysed: 304 samples of modern Phoenix spp. (including five herbarium type specimens and eight typeicons), 51 archaeological samples and nine fossil seed samples and subsamples. Information was systematized ina crude matrix with 364 units representing seed samples and 67 descriptors. Descriptors are frequencies, inpercentage, for each of the 41 qualitative states and of the 26 classes that were recognized for the quantitativeparameters. Analyses proceeded sequentially, starting with modern samples consisting of type specimens andbotanically verified specimens. Eight species show characteristic seeds and are clearly assigned to morphotypes[P. acaulis, P. canariensis s.s., P. paludosa, P. reclinata, P. roebelenii, P. rupicola, P. sylvestris and P. theophrasti(excluding populations from Datça, Turkey)]; the other taxa are not clearly separated on the basis of the seedmorphology alone. In parallel, fossil and archaeobotanical samples were analysed. There is no clear separationbetween fossil and archaeological samples, between different periods of the archaeological samples or geographicalorigins. Combination of modern, fossil and archaeological seed results in the same analysis revealed that it ispossible to allocate archaeological and fossil materials to morphotypes shared with modern living Phoenix spp. Allarchaeobotanical samples could be classified in groups with modern seed samples. The assignment of archaeobo-tanical samples was made, mainly, to morphotypes of P. dactylifera. However, some samples were assigned tomorphotypes of P. reclinata, P. caespitosa, P. atlantica, P. theophrasti, P. pusilla and P. canariensis. Archaeologicalseeds were not allocated to group 19, containing the samples of P. sylvestris, P. iberica and the Miocene fossilP. bohemica. It appears that species such as P. theophrasti, P. canariensis, P. caespitosa and P. reclinata formerly

*Corresponding author. E-mail: [email protected]

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Botanical Journal of the Linnean Society, 2014, 175, 74–122. With 25 figures

© 2014 The Linnean Society of London, Botanical Journal of the Linnean Society, 2014, 175, 74–12274

mailto:[email protected]

had a much wider area of distribution. The morphology of two of the three Eocene samples (Phoenicites occidentalisand Phoenix hercynica) is that of P. dactylifera. Attribution and dating of these samples need to be carefullyreviewed. Apparently the great diversity of P. dactylifera date morphotypes during the Neolithic was followed,during the Chalcolithic and the Bronze Age, by a remarkable constriction (bottleneck) in terms of morphologicalvariability, which slowly recovered from the Iron Age onwards. With the currently available evidence, we cannotexclude a group ancestral to P. dactylifera in the Persian Gulf, related to the eastern chlorotype. In parallel,another group ancestral to P. dactylifera may exist in the western Mediterranean, including P. iberica, related tothe western chlorotype. © 2014 The Linnean Society of London, Botanical Journal of the Linnean Society, 2014,175, 74–122.

ADDITIONAL KEYWORDS: Holocene – Miocene – multivariate analysis – palaeobotany – Palaeotropical –Phoenicites – Pleistocene – seed morphology – Tertiary.

INTRODUCTION

The genus Phoenix L. (Arecaceae) comprises 13(Barrow, 1998) to 20 (Beccari, 1890) species of mostlytropical, dioecious palms with solitary stems, rarelybranched, or, in some species, with a short under-ground stem, ending in a crown of 20–150 pinnateleaves. The fruits are berries (with a fleshy mesocarpand a membranous rudimentary endocarp), known as‘dates’, borne in clusters of tens or hundreds, whichdevelop from three-carpellate female flowers, inwhich two carpels normally abort.

The phylogenetic isolation of Phoenix has long beenestablished. It has been placed in tribe Phoeniceae(Uhl & Dransfield, 1987; Asmussen et al., 2006) insubfamily Coryphoideae, appearing to be the onlypalm group displaying the induplicate insertion ofleaf segments (Uhl et al., 1995; Dransfield et al.,2005). Phoenix differs from related genera of Coryph-oideae by having pinnate rather than palmate leaves.Although firmly anchored in Coryphoideae, Phoenixappears to be on a deep branch in phylogenetic trees,being sister to the large, pantropical tribe Trachy-carpeae (Dransfield et al., 2008). Molecular phyloge-netic dating placed the divergence of the Phoeniceaelineage during the early Tertiary (Couvreur, Forest &Baker, 2011).

Phoenix dactylifera L. (the date palm) has thewidest distribution and the highest morphologicaldiversity in Phoenix, and it is the most numerous interms of individuals and populations. Althoughhybrid origins have been proposed, molecular datahave demonstrated that P. dactylifera is a truespecies, distinct from all other species of the genus(Pintaud et al., 2010). Recent genetic data and phylo-genetic data based on DNA sequences of the plastidloci psbZ–trnfM and rpl16–rps3 indicate a stronggeographical structure of the genetic diversity of thedate palm at all scales (local, regional, global) and theimportance of isolation and intraspecific gene flow inshaping the present day agrobiodiversity. Althoughthere is no evidence of interspecific hybridization in

the cultivated gene pool, the status of P. atlanticaA.Chev. as distinct from P. dactylifera and its possiblepresence on the African continent (Mauritania andMorocco) need to be clarified (Pintaud et al., 2013).

Fruits (dates) normally develop after pollination,resulting in dates with seeds. Unpollinated femaleflowers may develop seedless, poor-quality fruits thatare normal in other respects. Date fruits are ellipsoi-dal to ovoid or almost cylindrical. Dimensions of datesare variable, ranging from 10 × 5 mm in P. roebeleniiO’Brien (Iossi, Vitti & Rubens, 2006), to 75 × 35 mmin P. dactylifera ‘Medjool’.

Phoenix seeds are typically elliptical and slightlyflattened dorsiventrally and have a longitudinalfurrow on the ventral face. On the dorsal face, theoperculum or micropyle appears at the middle point ofthe seed, although, often, it can be slightly displacedtowards the proximal or distal end. Only one species,P. paludosa Roxb., has a nearly basal operculum. Therigid date seeds (because of the hard endosperm) areerroneously called date ‘stones’ or ‘kernels’ in thearchaeobotanical literature, leading the reader tomisinterpret dates as drupes (Hopf, 1983; Kislev,Hartmann & Galili, 2004). Problems during pollina-tion and fruit development can lead to the incom-pletely developed or abnormal seeds.

Date fruits and their seeds present a set of charac-ters that are used as descriptors for the systematics ofPhoenix spp. and cultivars (Beccari, 1890; Barrow,1998; IPGRI, 2005). However, some of these charac-ters, such as testa colour, endosperm colour or thepresence/absence of a ruminate endosperm, cannot beused for identification of palaeobotanical materials,because they are lost during pre- and post-depositionalprocesses affecting the seeds. However, seed morphol-ogy is taxonomically relevant and several nomenclatu-ral types of Phoenix spp. are seeds or seed illustrations,for example, P. pusilla Gaertn. (Gaertner, 1788–1791).The shape of Phoenix seeds is characteristic and allowsdetermination of both fossil and archaeobotanical (car-bonized, desiccated or mineralized) materials at thegeneric level. However, in routine identifications of

CARPOLOGICAL ANALYSIS OF PHOENIX 75


palaeobotanical or archaeobotanical date seeds, it isuncommon for attributions to proceed beyond thegenus, generating a debate about whether they arewild or cultivated (Terral et al., 2012).

Fossils showing affinities with Phoenix seeds havebeen recorded from Tertiary levels of eastern Texas asPhoenicites occidentalis Berry (Berry, 1914), from themiddle Eocene of Germany (Geiseltal) as Phoenixhercynica Mai and Serenoa carbonaria Mai (Mai, 1976)and from the lower Miocene of Central Europe asPhoenix bohemica Buzek (Buzek, 1977; Harley, 2006).

Phoenix seeds were found in numerous archaeologi-cal sites from North Africa and the Near East, inlevels from the 8th millennium BP onwards. InAncient Egypt, dates were eaten fresh, dried and usedin magical compounds. One small carbonized seedwas recovered from Predynastic El Omari, Helwan(Debono, 1948). Date seed recovered in other prehis-toric settlements (Abu Umuri, Naqada) seem doubtful(Täckholm & Drar, 1950). Numerous finds are knownfrom later periods, including a dish with date frag-ments and seed (11th Dynasty, Ani’s tomb, El Gaba-lein) (Loret, 1892), dates [12th Dynasty, Dira Abu elNaga (Schweinfurth, 1883), 19th Dynasty, Thebes;21st Dynasty, tomb of Pinotem I, El Deir el Bahari],dates mixed with other fruits (16th Dynasty, Mayana;18th Dynasty, tomb of Khà, Thebes), seeds strung intonecklaces (New Empire and 18th Dynasty, Deir elMadina), small dates and seeds (18th Dynasty, tombof Sennufer, Thebes), date cakes (Early Ptolemaic,Thebes) and peculiar long narrow dates (Greek, ElFaiyum) (Täckholm & Drar, 1950).

Phoenix is a genus of wild and cultivated plantsthat can be found in a range of different natural (frommangroves to pine forests) and anthropogenic habi-tats (from sandy beaches to oases). This genus isnotoriously difficult to classify to the species levelbased on incomplete herbarium specimens and, evenin botanic gardens, outside their native habitats, indi-viduals of Phoenix can be seriously challenging toidentify. Phoenix dactylifera is found almost exclu-sively under cultivation, although occasionally, if con-ditions are favourable, there are feral and wildpopulations (Zohary & Hopf, 2000; Rivera et al.,2012b). Phoenix sylvestris (L.) Roxb. and P. canarien-sis H.Wildpret are systematically exploited for theirsweet sap to produce a concentrate known as palmhoney and the palms are often planted for thatpurpose in their natural areas, making it difficult todistinguish scattered crops and natural and feralpopulations. The other species are often found incultivation as ornamental palms or as rare specimensfor collectors. Several species were originally fully orin part described from specimens grown in botanicalgardens and collections, including P. reclinata Jacq.(Schönbrunn, Austria), P. canariensis (Orotava, Spain

or Cote d’Azur, France), P. acaulis Roxb. (Kolkata,India) and P. roebelenii (Protheroe & Morris, Leyton-stone, UK). Therefore, it is important, in sequence, tosolve taxonomic problems and difficulties of typifica-tion and then to proceed with analysing variability inpopulations of Phoenix, both wild and cultivated.

The first detailed descriptions of Phoenix seeds(P. dactylifera and P. pusilla) were by Gaertner(1788–1791), who used six characters totalling 11states. Gaertner did not, however, use any characterbased on the dimensions of the seeds (Table 1).

The first comprehensive monograph of Phoenix,published by Beccari (1890), used the position of themicropyle as a character for distinguishing species. Inthat work the number of characters (quantitative andqualitative) used to describe seeds is 15, totalling 38states. The most recent monograph of Phoenix byBarrow (1998) provides much less detailed descrip-tions of seeds, using only ten characters and 20 states(Table 1).

The need to create a set of descriptors to distinguishdate palm (P. dactylifera) cultivars and land races, ledresearchers to use descriptive characters already pub-lished by Beccari (1890) and to introduce others. Nixon(1950), for example, used only 11 characters, with atotal of 34 states; as quantitative descriptors he usedonly length and width. The official catalogue of stand-ardized descriptors for the date palm (IPGRI, 2005)(International Plant Genetic Resources Institute, nowBioversity International) comprises 12 characters and30 states referring to seeds (Table 1).

Terral et al. (2012) studied c. 1200 individualPhoenix seeds using dorsal and lateral outlines, and64 equally spaced points (pseudo-homologous land-marks) were analysed. However, raphe, micropyleposition, mucro and different superficial processeswere excluded from this analysis.

Morphological demarcation of species withinPhoenix involves numerous vegetative, floral, fruitand seed characters. Phoenix paludosa is easily dis-tinguished by its leaflet discolour (abaxial laminasurface greyish) and its seeds with a basal embryo.Leaflets with abaxial ramenta are typically present inP. andamanensis S.Barrow, P. reclinata, P. roebeleniiand P. rupicola T.Anderson (Barrow, 1998). In thegroup with ramenta, the few herbarium specimensavailable of P. andamanensis have seeds with a rumi-nate endosperm. Phoenix roebelenii is characterizedby its small size (stems to 2–3 m tall, leaves to 1.5 mlong), whereas stems to 10 m tall are typical of P. rec-linata (clustering) and P. rupicola (solitary). Acute toacuminate staminate petal apices with jaggedmargins are typical of P. reclinata (Barrow, 1998). Theprominent horn-shaped swelling of the rachilla, sub-tending each fruit, is exclusive to P. acaulis; in addi-tion, this species is acaulescent. Leaflets four-ranked,

76 D. RIVERA ET AL.


Tab

le1.

His

tori

cal

revi

ewof

the

use

ofse

edm

orph

olog

ical

char

acte

rsan

dst

ates

inP

hoe

nix

.C

odes

:B

,br

eadt

h;

D,

dept

h;

L,

len

gth

;T

D,

tota

lize

ddi

men

sion

s

Gae

rtn

er(1

788–

1791

)‡B

ecca

ri(1

890)

†N

ixon

(195

0)§

Bar

row

(199

8)IP

GR

I(2

005)

§T

his

pape

r

L(m

m)

Not

8–40

mm

,co

nti

nu

ous

18–3

6m

m,

con

tin

uou

s7–

30m

m,

con

tin

uou

sC

onti

nu

ous

4.47

–40,

con

tin

uou

sor

six

stat

es(4

–10,

10–1

5,15

–19,

19–2

5,25

–32,

32–4

0)B

(mm

)N

ot4.

5–12

mm

,co

nti

nu

ous

6.5–

11m

m,

con

tin

uou

s3–

10m

m,

con

tin

uou

sC

onti

nu

ous

1.31

–13(

15),

con

tin

uou

sor

six

stat

es(1

–3.5

,3.

5–6,

6–8,

8–10

,10

–12,

12–1

6)D

(mm

)N

ot4.

5–10

mm

,co

nti

nu

ous

Not

3–10

mm

,co

nti

nu

ous

Con

tin

uou

s0.

95–1

3(17

),co

nti

nu

ous

orfi

vest

ates

(0–2

.5,

2.5-

4,4–

5.5,

5.5–

7,7–

17)

B/L

Not

Not

Not

Not

Not

0.09

–1.1

7,co

nti

nu

ous

orfi

vest

ates

(0–0

.2,

0.2–

0.4,

0.4–

0.6,

0.6–

0.8,

0.8–

1)D

/BN

otN

otN

otN

otN

ot0.

32–1

.5,

con

tin

uou

sor

fou

rst

ates

(0–0

.75,

0.75

–0.8

5,0.

85–0

.95,

0.95

–1.5

)T

D(m

m3 )

Not

Not

Not

Not

Not

36–1

013

4,co

nti

nu

ous

orsi

xst

ates

(0–1

50,

150–

300,

300–

800,

800–

1200

,12

00–1

850,

1850

–10

200)

Ove

rall

shap

eTw

ost

ates

(obl

ong,

oblo

ng–

ovat

e)S

ixst

ates

(cyl

indr

ic,

com

pres

sed

from

base

toap

ex,

oblo

ng,

ovat

e–el

onga

ted,

ovat

e–tr

ian

gula

r,ov

ate–

elli

ptic

)

Sev

enst

ates

(nar

row

lyob

lon

g,ob

lon

g,ob

lon

g–el

lipt

ical

,ob

lon

g–w

edge

-sh

aped

,ob

lon

g–sp

ath

ula

te,

nar

row

lyel

lipt

ical

,ob

ovat

e–el

lipt

ical

)

Fiv

est

ates

(nar

row

lyel

onga

te,

elon

gate

,ob

ovoi

d,ov

oid,

tere

te)

Fiv

est

ates

(ovo

id,

con

ical

,fu

sifo

rm,

subc

ylin

dric

al,

pyri

form

)

Sev

enst

ates

(ova

te–t

rian

gula

r,el

lipt

ic,

oblo

ng,

cyli

ndr

ical

,gl

obos

e*,

hem

isph

eric

al,

fusi

form

)

Col

our

Two

stat

es(r

eddi

sh,

blac

kish

–bro

wn

)T

hre

est

ates

(gre

yish

,ch

estn

ut-

brow

n,

cin

nam

on-b

row

n)

Fiv

est

ates

(lig

ht

brow

n,

med

ium

brow

n,

grey

ish

brow

n,

ligh

tgr

eyis

hbr

own

,da

rkbr

own

)

Th

ree

stat

es(g

rey–

brow

n,

ches

tnu

t-br

own

,pi

nki

sh-b

row

n)

Th

ree

stat

es(b

eige

,gr

ey,

brow

n)

Fou

rst

ates

(bla

ckis

h,

grey

ish

,cr

eam

,br

own

)

Ape

xN

otTw

ost

ates

(rou

nde

d,ac

ute

)F

our

stat

es(b

lun

t,so

mew

hat

poin

ted,

som

ewh

atbr

oadl

ypo

inte

d,ro

un

ded)

Th

ree

stat

es(r

oun

ded,

poin

ted,

squ

ared

)N

otF

ive

stat

es(o

btu

se,

acu

te,

retu

se,

obli

que,

tru

nca

te)

Bas

eN

otTw

ost

ates

(rou

nde

d,ac

ute

)Tw

ost

ates

(abr

upt

,ot

her

s)T

hre

est

ates

(rou

nde

d,po

inte

d,sq

uar

ed)

Not

Fou

rst

ates

(obt

use

,ac

ute

,ob

liqu

e,tr

un

cate

)A

pica

lm

ucr

oN

otN

otTw

ost

ates

(pre

sen

t,la

ckin

g)N

otN

otTw

ost

ates

(pre

sen

t,la

ckin

g)B

asal

mu

cro

Not

Not

Not

Not

Two

stat

es(p

rese

nt,

lack

ing)

Two

stat

es(p

rese

nt,

lack

ing)



Tab

le1.

Con

tin

ued

Gae

rtn

er(1

788–

1791

)‡B

ecca

ri(1

890)

†N

ixon

(195

0)§

Bar

row

(199

8)IP

GR

I(2

005)

§T

his

pape

r

Su

rfac

eTw

ost

ates

(glo

ssy

and

smoo

th,

rou

ghan

dm

att)

Two

stat

es(g

loss

y,ro

ugh

)N

otTw

ost

ates

(glo

ssy,

mat

t)N

otTw

ost

ates

(glo

ssy

and

smoo

th,

rou

ghan

dm

att)

Lon

gitu

din

algr

oove

sTw

ost

ates

(pre

sen

t,la

ckin

g)T

hre

est

ates

(pre

sen

t,sh

allo

w,

lack

ing)

Not

Not

Not

Two

stat

es(p

rese

nt,

lack

ing)

Tran

sver

sepr

oces

ses

Th

ree

stat

es(s

moo

th,

wri

nkl

ed,

groo

ved)

Two

stat

es(fi

nel

ygr

oove

d,u

nif

orm

)N

otN

otF

our

stat

es(s

moo

th,

wri

nkl

ed,

bum

py,

groo

ved)

Th

ree

stat

es(w

rin

kled

,fi

nel

ygr

oove

d,u

nif

orm

)

Mic

ropy

leO

ne

stat

e(c

entr

al)

Two

stat

es(c

entr

al,

basa

l)F

our

stat

es(c

entr

al,

ali

ttle

abov

em

iddl

e,n

ear

base

,va

riab

le)

Two

stat

es(l

ater

al,

basa

l)T

hre

est

ates

(pro

xim

al,

cen

tral

,di

stal

)

Two

stat

es(c

entr

al,

basa

l)

Rap

he

Two

stat

es(d

eep,

wid

e)T

hre

est

ates

(sh

allo

w,

nar

row

,w

ide)

Six

stat

es(m

ediu

min

wid

than

dde

pth

,cl

osed

inth

ece

nte

r,cl

osed

,n

arro

wan

dsh

allo

w,

nar

row

and

deep

,op

en)

Not

Th

ree

stat

es(s

hal

low

,V

-sh

aped

,U

-sh

aped

)

Th

ree

stat

es(s

hal

low

,V

-sh

aped

,U

-sh

aped

)

Rap

he

len

gth

Not

Not

Not

Two

stat

es(f

ull

,in

com

plet

e)T

hre

est

ates

(Sh

ort,

Med

ium

,L

ong)

Not

Dor

so-v

entr

alcu

rvat

ure

Not

Two

stat

es(b

ent,

stra

igh

t)N

otN

otN

otTw

ost

ates

(ben

t,st

raig

ht)

Len

gth

wis

eri

dges

orw

ings

Not

Two

stat

es(p

rese

nt,

lack

ing)

Two

stat

es(p

rese

nt,

lack

ing)

Not

Fou

rst

ates

(lac

kin

g,w

ings

,ri

dges

,w

ings

and

ridg

es)

Two

stat

es(p

rese

nt,

lack

ing)

Fre

quen

cyof

ridg

esor

win

gs

Not

Not

Not

Not

Th

ree

stat

es(l

acki

ng,

occa

sion

ally

,fr

equ

entl

y)

Con

tin

uou

s,pe

rcen

tage

ofw

inge

dse

eds

Dor

sal

furr

owN

otT

hre

est

ates

(ver

ybr

oad,

very

open

,de

epan

dn

arro

w)

Two

stat

es(p

rese

nt,

lack

ing)

Not

Not

Not

*On

lyin

outg

rou

ps.

†Bec

cari

(189

0)si

tuat

esth

eve

ntr

alfa

ceof

the

seed

inth

ezo

ne

ofth

em

icro

pyle

,an

dth

edo

rsal

face

oppo

site

inth

ezo

ne

ofth

era

phe;

how

ever

,for

Ioss

iet

al.(

2006

)an

dIP

GR

I(2

005)

the

dors

alfa

ceis

the

zon

eof

the

mic

ropy

le.

‡Des

crip

tion

sar

ere

stri

cted

toon

lytw

osp

ecie

s.§D

escr

ipti

ons

for

Ph

oen

ixd

acty

life

racu

ltiv

ars

excl

usi

vely

.

78 D. RIVERA ET AL.


seed glossy, chestnut brown and stems short (rarely to4 m) are characteristic of P. pusilla. Leaflets not four-ranked, seed matt, greyish and stems short (rarely to4 m) are characteristic to P. loureiroi Kunth. Thegroup of robust tree palms with solitary trunksincludes P. canariensis (to 1.2 m in diameter) andP. sylvestris (to 30 cm in diameter). However, solitarystemmed P. dactylifera cultivars and seedlings arerelatively frequent. Clustering robust palms, oftenwith basal suckers, include P. atlantica A.Chev.,P. caespitosa Chiov., P. dactylifera L., P. ibericaD.Rivera, S.Ríos & Obón and P. theophrasti Greuter.Species in this last group do not appear clearly dif-ferentiated and there is discussion of their affinitiesand status (Gros-Balthazard, 2013).

Hybridization is a phenomenon considered to becommon among Phoenix spp. However, the allocationon morphological grounds of individuals or populationsto a particular hybrid is difficult and often erroneous.Morphometric approaches are postulated as a tool toidentify hybrids (Gros-Balthazard, 2013). González,Caujapé & Sosa (2004) gathered evidence for introgres-sion in mixed populations in Maspalomas and Tafira(Canary Islands, Spain) where pure P. canariensis andP. dactylifera (cultivated and feral) individuals withspecies-specific random amplified polymorphic DNA(RAPD) markers co-occur with morphologically inter-mediate individuals in which these markers are com-bined. However, natural interspecific hybridizationhas never been reported (Gros-Balthazard, 2013).Experimental pollination of several P. dactylifera cul-tivars with pollen of P. pusilla produced seedless dates.Although seed development was noted initially, thebreakdown of endosperm development was evidentlater on. Because of the development of disorders in theendosperm development, the embryo growth anddevelopment also ceased (Sudhersan, Jibi & Al-Sabah,2010). Therefore, not all possible crosses betweenPhoenix spp. are able to produce viable seeds andhybrids. Interspecific pollination events may influencethe dimensions of fruits and seeds as shown in differ-ent metaxenia experiments. For instance, P. dactylif-era cultivars produce smaller seeds when their femaleflowers are fertilized with pollen of P. canariensis orP. loireiroi (Gros-Balthazard, 2013). Therefore, it isnecessary to differentiate between hybrid seeds (modi-fied by metaxenia) and seeds produced by hybridfemale individuals of known parentage. For the pur-poses of the present paper we name ‘hybrid’ seeds ofthe second type, for their parentage we relied onpedigree records (experimental hybrids). Hybridsbetween P. dactylifera and P. canariensis have seeds ofintermediate size between the two species(Gros-Balthazard, 2013).

The purpose of the present study is, first, to analysemorphological characters of seeds from Phoenix spp.

and cultivars in order to assess the taxonomic valueof the generated information as a means of achievingmore promising research; i.e. a study of systematicsand the evolutionary history of the genus Phoenix,and, second, to compare seeds of living Phoenix spp.with palaeobotanical materials in an attempt todetermine ancestral states. We also analysed seedmorphological diversity in P. dactylifera, supported bymorphotypes shared with fossil and/or archaeologicalmaterials, to advance knowledge of the origins,history and biogeography of one of the most impor-tant cultivated palm species.

Other objectives are to develop a methodology toassign different commercial seed samples andarchaeological materials, to determined morphotypesas a tool for their identification to the species level.This will contribute to reduce the impact of misiden-tification in horticulture and will produce a frame-work for identification and interpretation ofarchaeobotanical Phoenix materials.

MATERIAL AND METHODSPLANT MATERIAL

Date palm seeds are rarely preserved as such incarpological collections or as herbarium specimens.For example, of the 480 sheets of Phoenix in theherbarium of the National Museum of NaturalHistory of Paris (France), only 13 contained fruitsmature enough to be able to extract seeds that couldbe analysed (but would destroy the fruit), and onlyone contained free and abundant seeds; in the Fair-child Tropical Botanic Garden Virtual Herbarium,only eight of 87 specimens had ripe fruits. Whenwhole date fruits are preserved in herbarium speci-mens, the extraction of seeds for study is not possiblewithout destroying the fruit; therefore, we onlystudied seeds which were free and clean. Herbariumspecimens were directly studied from the JardínBotánico de Madrid (MA), Herbarium of the Univer-sidad Miguel Hernández (UMH) and Beccari’s her-barium specimens in the Botanical Museum Florence(F) or using high resolution images from the BerlinBotanischer Garten (Röpert, 2000), Royal BotanicGarden, Edinburgh, Royal Botanic Gardens, Kew,Smithsonian Institution, Washington, and NationalMuseum of Natural History of Paris. In parallel, wecollected seed samples from living Phoenix individu-als in Algeria, France, Greece, Italy, Libya, Mexico,Morocco, Spain, Tunisia and Yemen. Seed sampleswere also obtained from botanic gardens (FairchildTropical Botanic Garden, Orto Botanico di Palermo,Orto Botanico ‘Pietro Castelli’ dell’Università diMessina, Orto Botanico dell’Università di Catania,Jardín Botánico de la Universidad de Valencia) and



repositories (National Clonal Germplasm Repositoryfor Citrus and Dates, Riverside, CA, USA). Finally,commercial samples of dates and horticultural seedswere acquired for comparison.

The species-level nomenclature (Table 2) followsBarrow (1998) and Govaerts et al. (2011), except forP. iberica D.Rivera, S.Ríos & Obón and P. canariensis.Phoenix iberica was described from the Chicamo area(Abanilla, Murcia), 40 km south-west of Elche, Spain.Originally it was based upon one small population ofspontaneous palms growing in a single ravine, and

scattered individuals living along the Chicamo River,but interspersed with individuals, or small clumps, ofthe local varieties of P. dactylifera. This taxon has notyet been found among the thousands of date palms inElche. Vegetatively, they are similar to P. theophrastiGreuter and their fruits are small, rounded with thinflesh and similar to the fruits of P. sylvestris. Theauthorship of P. canariensis is exhaustively discussedby Rivera et al. (2013a) and, in summary, it is H.Wild-pret in Chabaud, because Chabaud himself did notaccept the new species in the original publication and

Table 2. List of living Phoenix seed samples. Nomenclature adopted in this paper compared with Barrow (1998) andGovaerts et al. (2011). Further information on samples and vouchers in the Supporting Information and for accessionsINIA (2012) and Rivera et al. (2012a). NSAM, number of seed samples analysed; NT, number of type specimens; NI,number of type icons analysed

Species Barrow (1998) Govaerts et al. (2011) Main area NSAM NT NI

Outgroups 4 – –Phoenix acaulis Roxb. P. acaulis Roxb. P. acaulis Roxb. India 5 0 1Phoenix andamanensis

S.BarrowP. andamanensis

S.BarrowP. andamanensis

S.BarrowSouth-East Asia 1 1 0

Phoenix caespitosaChiov. (= P. arabicaBurret)

P. caespitosa Chiov. P. caespitosa Chiov. Arabia and Yemen 5 0 0

Phoenix atlanticaA.Chev.

¿P. atlantica A.Chev.? P. atlantica A.Chev. Cabo Verde 4 0 0

Phoenix canariensisH.Wildpret

P. canariensis Chabaud P. canariensis Chabaud Canary Islands 18 0 1

Phoenix dactylifera L.(including P. excelsiorCav.)

P. dactylifera L. P. dactylifera L. North Africa (fromEgypt westwards toAlgeria), Near East(Iran, Iraq, Arabiaand Yemen), Spain

164 0 1

Phoenix dactylifera L.var. adunca Becc.

P. dactylifera L. P. dactylifera L. Spain, Cabo Verde andNorth Africa

2 1 0

Phoenix dactylifera L.var. costata Becc.

P. dactylifera L. P. dactylifera L. Spain and BajaCalifornia (Mexico)

2 1 0

Phoenix interspecifichybrids

– – – 17 0 0

Phoenix ibericaD.Rivera, S.Ríos &Obón

Not included P. dactylifera L. Spain 0 1 0

Phoenix loureiroi Kunth P. loureiroi Kunth P. loureiroi Kunth South-East Asia andIndia

24 1 0

Phoenix paludosa Roxb. P. paludosa Roxb. P. paludosa Roxb. South-East Asia 5 0 0Phoenix pusilla Gaertn. P. pusilla Gaertn. P. pusilla Gaertn. India and Sri Lanka 2 0 3Phoenix reclinata Jacq. P. reclinata Jacq. P. reclinata Jacq. Africa 4 0 1Phoenix roebelenii

O’BrienP. roebelenii O’Brien P. roebelenii O’Brien South-East Asia 8 0 0

Phoenix rupicolaT.Anderson

P. rupicola T.Anderson P. rupicola T.Anderson India 6 0 0

Phoenix sylvestris (L.)Roxb.

P. sylvestris (L.) Roxb. P. sylvestris (L.) Roxb. India 12 0 1

Phoenix theophrastiGreuter

P. theophrasti Greuter P. theophrasti Greuter Crete and South-westTurkey

8 0 0

80 D. RIVERA ET AL.


published a description of the species by HermannWildpret. The type of P. caespitosa Chiov. was col-lected in north-eastern Somalia, our samples werecollected in the classical locality of P. arabica Burretin Yemen and from plants introduced from SaudiArabia into the USA and from cultivars. Barrow(1998) and Govaerts et al. (2011) both consideredP. arabica to be conspecific with P. caespitosa.

Three hundred and sixty-four seed samples total-ling 3920 seeds were analysed. Also, 286 samples ofmodern seeds were desiccated and reduced to c. 20%moisture content using a Sicco Auto-Star Desiccator,and preserved with Scharlau silica gel with a humid-ity indicator (orange), 2.5–6.0 mm, at 5 °C in twoLiebherr K42 refrigerators. These seeds wereobtained from living Phoenix spp. and cultivars andfour outgroups (Euterpe Mart., Livistona R.Br., Nan-norrhops H.Wendl. and Washingtonia H.Wendl.). Lotscomprising c. 15 seeds each were analysed. Voucherspecimens have been deposited in the UMH (MiguelHernández University) herbarium and carpologicalcollection (Table 2 and see also Supporting Informa-tion, Appendix S1). These samples derive from fieldcollections (119), horticultural samples (64), commer-cial date fruits (60) and botanic gardens and reposi-tories (43). The samples analysed were randomlyselected as subsamples from samples usually contain-ing 25–1000 seeds. From each sample, another sub-sample of five to 25 randomly selected seeds wasregularly sown, germinated and the plants grown inthe National Phoenix repository (Escuela PolitécnicaSuperior, Universidad Miguel Hernández and Soto I6,Ayuntamiento de Orihuela and Confederación Hidro-gráfica del Segura, both in Orihuela, Spain) (INIA,2012; Phoenix Spain, 2013).

Five samples of herbarium type specimens and fiveother relevant herbarium specimens were measured(Table 2). Eight icons or figures previously designatedas nomenclatural types for Phoenix spp. were ana-lysed, interpreted and measured (Table 2).

Fifty-one archaeological and nine fossil seed samplesand subsamples, each comprising one to 39 seeds, weremeasured using images and data available in theoriginal publication or provided by different research-ers, herbaria, museums and repositories (Table 3).

MEASUREMENTS AND QUALITATIVE

CHARACTERS ANALYSED

We used 20 descriptive characters relating to seed. Ofthese, three are quantitative, two are allometric rela-tionships, one is based on totalized dimensions (prismvolume, defined as the length, width and thickness ofthe seed) and 14 are qualitative. Recognized states ofqualitative characters totalled 41. In selecting thecharacter set, and the states thereof, we took into

account previous studies (Beccari, 1890; Barrow, 1998;IPGRI, 2005) and observation of the samples analysed.Terminology for characters and states follows Stearn(1978), Barrow (1998) and IPGRI (2005).

Each of the 3920 seeds was individually describedusing the 20 characters as given in Table 1. Quanti-tative characters were measured using a MitutoyoAbsolute Digimatic 500-202-21 digital caliper with aprecision of 0.01 mm and recorded on an Excel spreadsheet. Allometric relationships (B/L, D/B) and total-ized dimensions (L × B × D in mm3) were automati-cally calculated using formulas.

Qualitative characters were analysed with a bin-ocular Olympus SZ microscope and a Philips 220CWflat screen. Photographs of ventral, dorsal and lateralviews were taken for all samples using a Lumix FZ60camera with a Leica DC lens. Another full set ofimages was obtained using a Canon EOS 350Dcamera. A second observer verified the qualitativedata using these photographs.

Individual seeds differ slightly in shape and dimen-sions within the same palm and even the same bunchand branchlet. Therefore, our interest was to developa method to compare individuals, cultivars andspecies, depending on their overall seed morphology.To describe sample observations and measurementsof the individual seeds they were converted to discretecategories and frequencies within each of thesamples. This allowed us to compare samples interms of not only mutually exclusive states or averagevalues, but also in terms of the proportion of seeds ofeach sample presenting those states.

To calculate frequencies in the cases of continuousquantitative parameters such as dimensions (length,width and thickness), allometric relationships and thetotalized dimensions and to compare the samples,parameters were each reduced to four to six classes orcategories. Samples were then analysed in terms ofcounts (proportion of individual seeds falling withinthe class) and expressed as a percentage (Tables 4and 5). This allowed us to use quantitative and quali-tative characters together in a single matrix.

Information was systematized in a crude matrixwith 364 units (seed samples) (Table 1 and Support-ing Information, Appendix S1) and 67 descriptors.Descriptors are frequencies, as a percentage, for eachof the 41 qualitative states and 26 classes that wererecognized for the quantitative parameters (Tables 4and 5). The crude matrix is presented as SupportingInformation (Appendix S2).

DATA ANALYSES

The crude matrix was used to compute a dissimilaritymatrix using Darwin 5 V.5.0.158 (2009-07-06)(Perrier, Flori & Bonnot, 2003; Perrier &



Tab

le3.

Lis

tof

foss

ilan

dar

chae

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anic

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hoe

nix

seed

sam

ples

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SE

E,

nu

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san

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ain

area

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(yea

rs)

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orth

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eric

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4000

000

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ry.

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ity

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tern

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ther

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un

ty.

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eral

ized

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erry

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14

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man

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e_G

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3500

000

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Gei

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1976

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man

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Gei

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1976

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2000

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Min

eral

ized

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-pal

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imen

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77

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ece

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3700

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stem

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also

fru

itse

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den

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edby

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date

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82 D. RIVERA ET AL.


Lib

yaN

orth

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lith

ic_L

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Car

bon

ized

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s,fr

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sam

ples

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date

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from

Per

iod

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d22

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1999

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esti

ne

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tA

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alco

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T_

1–6

5600

Tele

ilat

Gh

assu

lC

arbo

niz

edda

tese

eds

6N

esbi

tt,

1993

;H

opf,

1983

;L

evy,

1986



Tab

le3.

Con

tin

ued

Cou

ntr

yM

ain

area

Cod

eD

ate

BP

(yea

rs)

Sit

eL

ocM

ater

ials

NS

EE

Ref

eren

ce

Iran

Wes

tA

sia

Bro

nze

Age

_KA

RR

_150

00Te

llK

arra

na

3R

16Te

ll Kar

ran

aO

ne

desi

ccat

edda

tese

ed(1

9.72

×7.

81×

7.58

mm

)w

asfo

un

don

the

floo

rin

the

area

R16

ofB

ron

zeA

gebe

dsof

Tell

Kar

ran

a3

1C

osta

nti

ni

&C

osta

nti

ni-

Bia

sin

i,19

93

Isra

elW

est

Asi

aB

ron

zeA

ge_J

ER

ICH

O46

00Je

rich

oJe

rich

oO

ne

desi

ccat

edda

tese

ed1

Hop

f,19

83

Iraq

Wes

tA

sia

Bro

nze

Age

_UR

_1–4

4500

Qu

een

Pu

-abi

’sgr

ave

Ur

Man

yfr

agm

ents

ofde

sicc

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un

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ller

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la,

2001

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ron

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1–39

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etc.

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s al-J

inz

RJ-

3

Car

bon

ized

Ph

oen

ixd

acty

life

rafr

uit

san

dse

eds

and

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yph

us

fru

its

39C

osta

nti

ni

&A

udi

sio,

2000

Ku

wai

tW

est

Asi

aB

ron

zeA

ge_

FAIL

AK

A1-

340

0011

29.A

QS

Fai

laka

Car

bon

ized

date

seed

s3

Row

ley-

Con

wy,

1987

cite

dby

Bee

ch,

2003

;N

esbi

tt,

1993

;W

illc

ox&

Ten

gber

g,19

95Ye

men

Wes

tA

sia

Bro

nze

Age

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oca

sts

ofda

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edw

ere

fou

nd

inpo

tter

y(c

.10.

7m

mlo

ng

and

10.0

9×

6.88

mm

)

2C

osta

nti

ni,

1991

;N

esbi

tt,

1993

Bah

rain

Wes

tA

sia

Bro

nze

Age

_SA

AR

1-13

and

14–1

6

3700

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1991

E16

:10:

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aar

Th

eva

riat

ion

inle

ngt

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–19.

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kin

gan

dit

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ssib

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at,

once

larg

en

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bers

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are

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rm

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ent,

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ster

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diff

eren

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form

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riet

ies

may

beco

me

appa

ren

t.D

ilm

un

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arbo

niz

ed

16N

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tt,

1993

84 D. RIVERA ET AL.


Yem

enW

est

Asi

aIr

on Age

_RA

YB

U_1

to12

2800

SI

(N=

25),

S2

(N=

15),

S3

(N=

30),

R(N

=50

),

Ray

bun

Ph

oen

ixse

eds

(20–

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9.3

mm

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7×

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mm

),po

llen

and

leaf

rem

ain

sw

ere

fou

nd

inth

esi

teof

Ray

bun

(Sou

thA

rabi

a).

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icca

ted

tom

iner

aliz

ed

1L

evko

vska

ya&

Fil

aten

ko,

1992

Iran

Wes

tA

sia

Neo

-Ela

mit

e_S

US

A_1

–226

50B

uri

al69

3–68

61S

usa

Dat

esse

emto

hav

ebe

enu

sed

asa

fun

erar

yof

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ng

inth

eN

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ite

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al69

3.D

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d

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ille

r,19

81

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diA

rabi

aW

est

Asi

aIr

on Age

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2600

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isTa

yma

Taym

aS

ubf

ossi

lde

sicc

ated

seed

s4

Nee

f,C

appe

rs&

Bek

ker,

2011

Isra

elW

est

Asi

aR

oman

_MA

SS

A_

1–4

2120

Mas

ada

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ther

nD

istr

ict

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oen

ixd

acty

life

rade

sicc

ated

fru

its.

At

leas

ton

ese

edw

asab

leto

germ

inat

e

4S

allo

net

al.,

2008

Iran

Wes

tA

sia

Par

thia

n_S

US

A20

50S

usa

Sh

ush

On

ede

sicc

ated

date

seed

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aly

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rope

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ouse

ofth

eS

hip

Eu

ropa

,a

sin

gle

carb

oniz

edse

ed1

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er,

1980

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yE

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peR

oman

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OM

PE

I_4b

1990

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peii

Nap

les

Mu

seu

min

ven

tory

50.

8463

0da

tefr

uit

s33

×12

mm

and

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m

1W

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ack,

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nce

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rope

Rom

an_L

AT

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raL

atte

sA

mon

gth

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uit

san

dse

eds

burn

tin

this

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rin

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five

seed

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ght

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its.

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bon

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ovir

a&

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abal

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ica

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an_

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anis

Kom A

ush

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ossi

lde

sicc

ated

fru

its

and

seed

s18

Nee

fet

al.,

2011

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igio

us

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rin

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ur

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eds.

Gu

anch

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riod

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oral

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al.,

2011

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opic

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ller

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00

We

shou

ldn

ote

that

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pari

son

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mat

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ls(s

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edin

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inth

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ater

ials

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cern

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erva

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ical

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ure

sdu

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We

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Table 4. Quantitative parameters analysed in modern and archaeological and fossil Phoenix seed samples. FosAr, fossiland archaeological materials; B, breadth; D, depth; L, length; TD, totalized dimensions

a. Quantitative characters (continuous)

Parameters

Total Modern FosAr

Min Max Min Max Min Max

L (mm) 4.47* 40.00 4.47 37.83 5.50 40.00B (mm) 1.31* 15.00 1.31 12.87 3.20 15.00D (mm) 0.95* 16.89 0.95 12.87 3.20 16.89B/L 0.09 1.17 0.09 1.17 0.23 0.70D/B 0.32 1.50 0.32 1.50 0.46 1.33TD (mm3) 36.62* 10 134.00 36.62 3656.83 56.32 10 134.00

*These values correspond to abnormal seeds not fully developed.

b. Quantitative characters in states or classes. Data in percentage of samples analysed. Dimensions in mm. B,breadth; D, depth; L, length

Type L 4–10 L 10–15 L 15–19 L 19–25 L 25–32 L 32–40

Modern 10.3 23.1 22.7 30.0 13.0 0.8FosAr 2.5 24.3 16.5 44.9 5.6 2.8

Type B 1–3.5 B 3.5–6 B 6–8 B 8–10 B 10–12 B 12–16

Modern 1.4 12.1 25.9 43.5 16.4 0.6FosAr 0.6 12.2 47.2 30.3 4.7 1.7

Type D 0–2.5 D 2.5-4 D 4–5.5 D 5.5–7 D 7–17

Modern 1.1 5.5 10.9 24.1 58.1FosAr 0.0 0.6 20.1 48.3 27.6

c. Allometric characters and totalized dimensions in states. Data in percentage of samples analysed. B, breadth; D,depth; L, length; TD, totalized dimensions. Totalized dimensions in mm3.

Type B/L 0–0.2 B/L 0.2–0.4 B/L 0.4–0.6 B/L 0.6–0.8 B/L 0.8–1

Modern 1.0 26.9 56.4 14.4 1.3FosAr 0.0 42.9 48.0 5.3 0.4

Type D/B 0–0.75 D/B 0.75–0.85 D/B 0.85–0.95 D/B 0.95–1.5

Modern 8.5 32.7 52.6 6.2FosAr 16.7 20.2 32.6 27.2

Type TD 0–150 TD 150–300 TD 300–800 TD 800–1 200 TD 1 200–1 850 TD 1 850–10 200

Modern 4.7 6.9 19.9 19.4 33.9 15.3FosAr 1.1 4.2 38.2 28.1 17.5 7.7

86 D. RIVERA ET AL.


Tab

le5.

Qu

alit

ativ

ech

arac

ters

anal

ysed

inm

oder

nan

dar

chae

olog

ical

and

foss

ilP

hoe

nix

seed

sam

ples

.D

ata

inpe

rcen

tage

ofsa

mpl

esan

alys

ed.

Fos

Ar,

foss

ilan

dar

chae

olog

ical

mat

eria

ls;

OC

,ov

ate–

tria

ngu

lar;

EL

,el

lipt

ic;

OB

,ob

lon

g;C

Y,

cyli

ndr

ic;

GL

,gl

obos

e;H

E,

hem

isph

eric

al;

FU

,fu

sifo

rm;

AO

,ap

exob

tuse

;A

A,

apex

acu

te;

AR

,ap

exre

tuse

;A

B,

apex

obli

que;

AT

,ap

extr

un

cate

;B

O,

base

obtu

se;

BA

,ba

seac

ute

;B

L,

base

obli

que;

BT

,ba

setr

un

cate

Sh

ape

OC

EL

OB

CY

GL

HE

FU

Mod

ern

5.94

20.2

544

.88

19.4

51.

091.

397.

01F

osA

r3.

6816

.56

28.2

250

.92

0.61

0.00

0.00

Col

our

Bla

ckis

hG

reyi

shC

ream

Bro

wn

Mod

ern

1.20

2.05

37.0

359

.90

Ape

xA

OA

AA

RA

BA

TB

ase

BO

BA

BL

BT

Mod

ern

83.8

712

.69

0.19

0.18

2.87

Mod

ern

44.1

715

.29

3.97

36.2

7F

osA

r89

.57

4.91

0.00

0.00

5.52

Fos

Ar

50.3

129

.45

6.13

14.1

1

Api

cal

mu

cro

Pre

sen

tL

acki

ng

Bas

alm

ucr

oP

rese

nt

Lac

kin

g

Mod

ern

12.5

87.5

Mod

ern

6.1

93.9

Fos

Ar

0.0

100.

0F

osA

r1.

598

.5

Su

rfac

eG

loss

yan

dsm

ooth

Rou

ghan

dm

att

Lon

gitu

din

algr

oove

sP

rese

nt

Lac

kin

gTr

ansv

erse

proc

esse

sW

rin

kled

Fin

ely

groo

ved

Un

ifor

m

Mod

ern

44.8

55.2

Mod

ern

27.1

472

.86

Mod

ern

34.3

48.

3957

.27

Fos

Ar

34.3

665

.64

Fos

Ar

10.4

389

.57

Fos

Ar

57.0

61.

2341

.72

Mic

ropy

leC

entr

alB

asal

Rap

he*

Sh

allo

wV

-sh

aped

U-s

hap

ed

Mod

ern

97.5

2.5

Mod

ern

13.5

333

.06

53.4

1F

osA

r10

0.0

0.0

Fos

Ar

41.1

023

.31

35.5

8

*Len

gth

wis

eve

ntr

alfu

rrow

.

Dor

so-v

entr

alcu

rvat

ure

Ben

tS

trai

ght

Len

gth

wis

ecr

ests

orw

ings

Pre

sen

tL

acki

ng

Mod

ern

5.01

94.9

9M

oder

n2.

497

.6F

osA

r0.

010

0.0

Fos

Ar

0.0

100.

0



Jacquemoud-Collet, 2006). The χ2 dissimilarity indexwas calculated. This measure expresses a value xik asits contribution to the sum xi on all variables and is acomparison of unit profiles:

dxx

xx

xx

ijk

Kik

i

jk

j

= −⎛⎝⎜

⎞⎠⎟∑ ..

. . .1

2

where dij is the dissimilarity between units i and j; xik

and xjk are the values of variable k for units i and j;xi., xj. and x.k are the mean for units i and j or variablek; x. is the overall mean. K is the number of variables.

Dissimilarities are even and Euclidean distances.Principal coordinates analysis (PCoA), which works

on dissimilarity matrices showing the distancebetween every possible pair of samples, was used togive an overall representation of diversity withinPhoenix seeds with the lowest possible dimensionalspace. This represented a step in the analysis of thestructure of diversity in the genus Phoenix.

To represent individual relationships realistically, ahierarchical tree was constructed to describe the rela-tionships between units (samples) based on thecommon agglomerative heuristic that proceeds bysuccessive ascending agglomerations. For updatingdissimilarity during the tree construction, the Wardcriterion was adopted, which searches at each step fora local optimum to minimize the within-group or,equivalently, to maximize the between-group inertia.The distance between two elements is the weightedsquare of the Euclidean distance between theirgravity centres.

A weighted neighbor joining tree was used to verifyclose similarities between samples. The neighborjoining method proposed by Saitou & Nei (1987) usesthe criterion of relative neighbourhood, weightedaverage for dissimilarity updating and adjustment toan additive tree distance. A bootstrap value is given toeach edge that indicates the occurrence frequency ofthis edge in the bootstrapped trees. Bootstrap valuesrange between 0 and 100. Radial trees were drawnusing Dendroscope (Huson & Scornavacca, 2012) andFigTree (Rambaut, 2012).

To verify stability of the results and to developmethodologies for allocating to morphotypes gener-ated in function of species, cultivars and archaeologi-cal and fossil seed samples, the above methodologywas conducted in four stages. First, similarity wascalculated using only a sub-matrix formed by 165units or samples, which included the herbariumspecimens, types and those samples collected in thefield, or from repositories, that were botanically iden-tified, taking into account other characters of thepalm and 63 variables or descriptors. Excluded fromthis analysis were variables or descriptors for whichall of the samples had zero frequency. After that, a

second analysis was performed incorporating com-mercial samples of dates, and seeds intended for usein horticulture and gardening totalling 303 units orsamples and 67 variables or descriptors. This analysisalso included several samples of immature seeds fromdates abnormally ripened. In parallel, fossil andarchaeological seed samples were analysed totalling60 units and 52 variables. Excluded from this analy-sis were variables or descriptors for which all of thesamples had zero frequency, i.e. colour of the seed.Finally, modern and fossil and archaeological sampleswere included in a fourth analysis, with 364 unitsthat are seed samples (Table 1 and Supporting Infor-mation, Appendix S1) and 67 descriptors.

RESULTSSEQUENTIAL ORDER OF THE ANALYSIS

The first analysis, which included only herbariumtype material, type icons and botanically verifiedsamples collected in the field and in repositories,produced seven main clusters reflected in the hierar-chical phenetic tree (Fig. 1). A first branching sepa-rates outgroups (Euterpe, Livistona, Nannorrhops,Washingtonia), and P. paludosa, from the seeds ofother Phoenix spp. Then two groups are clearly sepa-rated depending on seed size. The first group, withlarge seeds, includes numerous samples of P. dactyl-ifera (including the type icon) and seeds of P. atlantica(including original material collected by Chevalier),P. sylvestris (including the type icon), P. canariensisvar. macrocarpa H.Wildpret (material collected by theauthor) and the nomenclatural type of P. iberica. Thesecond group includes samples from all other Phoenixspp. Then the minute and thin seeds of P. roebeleniiare separated, followed by P. rupicola and P. canar-iensis. A low-resolution group brings together theseeds of P. theophrasti, P. reclinata Jacq., P. caespitosa(P. arabica) and P. pusilla. Samples of the palm withbluish fruits, named P. senegalensis André, fall withinthe groups of P. theophrasti–P. caespitosa (P. arabica)and of P. pusilla–P. reclinata. In parallel, there isanother group with the seeds of P. loureiroi Kunth,P. acaulis (including the type icon), P. andamanensisS.Barrow (nomenclatural type) and the type icon ofP. farinifera Roxb.

A second analysis including commercial seedsamples resulted in an overall structure similar to theabove, clearly separating P. dactylifera and relatedtaxa from the group of smaller seeded species.However, some major changes may be noticed. Thesamples attributed to P. theophrasti collected in Datçaand Gölköy (south-western Turkey) appear here clus-tered with different P. dactylifera samples (with rela-tively small seeds) from Spain and Baja California

88 D. RIVERA ET AL.


(Mexico) and no longer with those of P. theophrastifrom Crete. Again, seeds of P. andamanensis fallwithin the variability of P. loureiroi. Eleven horticul-tural samples of P. sylvestris cluster around the typeof the species on a branch that contains numerousP. dactylifera samples from Elche and other localities

in south-eastern Spain. Immature seeds, from unripefruits, or sterile seeds are abnormally small or thin,and a group of these clusters among the samples ofP. roebelenii and of hybrids of this with other species.

The third analysis was performed exclusively withfossil and archaeobotanical seed samples. Obviously

Figure 1. Hierarchical tree calculated using the algorithm of Ward with Phoenix type specimens and botanically verifiedmodern seed samples. Branchlets labelled gray correspond to Phoenix dactylifera.



the depositional and post-depositional processesreduced the number of variables or descriptors avail-able from 67 to 52. The resulting weighted neighborjoining tree shows relationships with > 50% coinci-dence of the 5000 bootstraps (Fig. 2). Surprisingly,there is no clear separation between fossil andarchaeological samples, between different periods ofthe archaeological samples, between geographicalorigins or between forms of preservation. Percentages> 75% of coincidence are found only between seedsfrom the same site, except for Bronze Age seed samplesfrom Ras al Jinz (Oman) and Failaka (Kuwait) (bothcarbonized).

In the fourth analysis, with 364 samples includingfossil and archaeobotanical materials, PcoA and hier-archical clustering using Ward’s algorithm (Fig. 3A–C)show four main clusters that include 24 groups and oneoutgroup. Furthermore, at least eight species havecharacteristic seeds and are clearly assigned to mor-photypes [P. acaulis, P. canariensis s.s., P. paludosa,P. reclinata, P. roebelenii, P. rupicola, P. sylvestris andP. theophrasti (excluding populations of Datça, Turkey)(Fig. 3, Table 6)], the rest are not clearly separated onthe sole basis of the morphology of seeds.

Characters and states that provide information toseparate different groups behave differently. Some areinfrequent: hemispheric seeds, seeds blackish, widthto 3.5 mm, B/L to 0.1 or, conversely, 0.8 to 1.0, andserve to differentiate isolated groups, whereas otherssuch as the U-shaped opposed to the V-shaped ventralraphe are recurrent for differentiation of variousgroups. Within each group, those states which arerelevant for describing the group are marked in bold.Frequency within the seeds of each group is presentedas a percentage between parentheses. Percentages> 95% are not shown (see Figs 3A, 4). In the Support-ing Information (Appendix S3) is attached the matrixof correlation between variables.

CLUSTER I

This cluster includes small seeds, short (length usually< 15 mm), with totalized dimensions from c. 150 to800 mm3 and surface generally even, uniform.

Group 1: includes small seeds of different subspe-cies of P. loureiroi from India and East Asia, with thenomenclatural type of P. andamanensis (which onlydiffers in the ruminate endosperm), several misla-belled commercial samples and one interspecifichybrid. Main descriptive parameters: Breadth/Length = 0.4–0.6 (84%). Length = 10–15 mm (87%).Breadth = 3.5–8.0 mm (94%). Depth = 4–7 mm.Totalized dimensions = 300–800 mm3 (82%). Elliptic(32%) to oblong (63%). Cream coloured (83%). Apexobtuse (93%). Base obtuse (72%). Surface rough (69%),uniform. With longitudinal grooves (72%). Micropyle

near the middle of the dorsal face. Ventral rapheU-shaped (91%). Dorsoventrally straight. Not winged.

Group 2: includes small seeds of P. acaulis fromIndia and the type icon of the species. Within thisgroup are also the type icons of P. zeylanica Trimenand P. pusilla Gaertn. Main descriptive parameters:Breadth/Length = 0.4–0.6 (86%). Length = 10–15 mm (87%). Breadth = 3.5–8.0 mm. Depth = 4–7 mm. Totalized dimensions = 300–800 mm3.Oblong. Cream coloured (71%) or brown (29%). Apexobtuse. Base obtuse (86%). Surface rough (71%),uniform. With longitudinal grooves (57%). Micropylenear the middle of the dorsal face. Ventral rapheV-shaped (29%) or U-shaped (71%). Dorsoventrallybent (82%). Not winged.

Group 3: includes small seeds of P. loureiroi fromsouth-eastern China, P. reclinata hybrids and twosamples from cultivated palms tentatively identifiedas P. caespitosa. And one horticultural seed samplelabelled as P. canariensis. Main descriptive param-eters: Breadth/Length = 0.6–0.8 (75%). Length = 10–15 mm (75%). Breadth = 6–8 mm (77%). Depth = 5.5–12.0 mm. Totalized dimensions = 300–800 mm3 (90%).Elliptic (95%). Cream coloured (40%) or brown (60%).Apex obtuse. Base obtuse (72%) or truncate (28%).Surface rough (63%) or smooth (37%), uniform. Withlongitudinal grooves (89%). Micropyle near themiddle of the dorsal face. Ventral raphe U-shaped.Dorsoventrally straight. Not winged.

Group 4: includes small seeds of P. reclinata, com-prising the type icon of the species. It also includeseveral Bronze Age archaeological samples fromArraqis, Jericho, Saar and Hili, and Roman samplesfrom Karanis, and a sample of a bluish date known asP. senegalensis. Main descriptive parameters:Breadth/Length = 0.4–0.6 (74%) or 0.6–0.8 (24%).Length = 10–15 mm. Breadth = 6–8 mm (91%).Depth = 5.5–7.0 mm. Totalized dimensions = 300–800 mm3 (97%). Oblong (37%), Ovoid–triangular(24%). Brown coloured (modern seeds). Apex obtuse.Base obtuse (67.5%) or truncate (30%). Surface rough(50%) or smooth (50%), uniform (68.75%) or wrinkled(31.25%). Without longitudinal grooves. Micropylenear the middle of the dorsal face. Ventral rapheV-shaped (34%) or U-shaped (66%). Dorsoventrallystraight. Not winged.

Group 5: includes small seeds of P. theophrasti s.s.(several samples from Crete and one from Gölköy) witha Neolithic sample from Atlit Yam (Israel) and severalarchaeological samples. Main descriptive parameters:Breadth/Length = 0.4–0.6. Length = 10–15 mm.Breadth = 3.5–8.0 mm (91%). Depth = 5.5–12.0 mm.Totalized dimensions = 300–800 mm3 (70%) or 800–1200 mm3 (25.5%). Elliptic (63.6%), oblong (20.5%).Brown coloured (modern seeds). Apex obtuse. Baseobtuse. Surface smooth, uniform. With longitudi-

90 D. RIVERA ET AL.


Figure 2. Tree calculated with the weighted neighbor joining algorithm. A, archaeological desiccated and brick casts (red)and fossil Phoenix seed samples (blue). B, carbonized seeds (black). Bootstrap values below 30% are omitted.



nal grooves (81.8%). Micropyle near the middle of thedorsal face. Ventral raphe shallow. Dorsoventrallystraight. Not winged.

Group 6: includes small seeds of P. pusilla, thetype icon of P. farinifera [according to Barrow, (1998)and Govaerts et al. (2011) a synonym of P. pusilla]and seeds of P. loureiroi (P. hanceana Naudin) andP. roebelenii hybrids. It also includes several archaeo-logical samples and Eocene fossils from Geiseltalnamed Serenoa carbonaria (Mai, 1976). Main descrip-tive parameters: Breadth/Length = 0.4–0.8 (78%).Length = 4–15 mm. Breadth = 3.5–6.0 mm (85.4%).Depth = 4.5–5.5 mm (80%). Totalized dimen-sions = 150–300 mm3 (71.2%) or 300–800 mm3

(25.1%). Elliptic (48.5%), oblong (25%). Cream (50%)or brown (25%) coloured (modern seeds). Apex obtuse.Base obtuse (66.7%) or truncate (33.3%). Surfacesmooth (75%) or rough (25%), uniform. Withoutlongitudinal grooves (66.7%). Micropyle near themiddle of the dorsal face. Ventral raphe U-shaped(83%). Dorsoventrally straight. Not winged.

Group 7: exclusively includes small seeds of P. rupi-cola. Main descriptive parameters: Breadth/Length = 0.4–0.6. Length = 10–15 mm (75%) and15–19 mm (25%). Breadth = 6–8 mm (85.8%).Depth = 5.5–7.0 mm (82.7%). Totalized dimen-sions = 300–800 mm3 (84.9%) or 800–1200 mm3 (11%).Oblong. Greyish coloured. Apex obtuse. Baseobtuse (66.7%) or truncate (33.3%). Surface rough,uniform. With longitudinal grooves. Micropyle nearthe middle of the dorsal face. Ventral raphe shallow(83%). Dorsoventrally bent (90%). Not winged.

Group 8: includes small seeds of P. canariensis cul-tivars, one sample of P. caespitosa (P. arabica) andarchaeological samples from the Guanche Period(Canary Islands, Spain) and Roman Karanis. Maindescriptive parameters: Breadth/Length = 0.4–0.8.Length = 10–15 mm (75%) and 15–19 mm (25%).Breadth = 6–8 mm (54%) and 8–10 mm (38%).Depth = 5.5–7.0 mm (60%) and 7.0–12.0 mm (40%).Totalized dimensions = 300–800 mm3 (56%) or 800–1200 mm3 (44%). Elliptic (30%), oblong (45%). Browncoloured. Apex truncate. Base truncate (80%).Surface smooth (50%) or rough (50%), uniform (90%) orwrinkled (10%). With longitudinal grooves (63%).Micropyle near the middle of the dorsal face. Ventral

raphe shallow (75%). Dorsoventrally straight. Notwinged.

CLUSTER II

This cluster includes small seeds of P. roebelenii andimmature seeds of other species with totalized dimen-sions < 300 mm3.

See Figures 3A and 4.Group 9: almost exclusively includes small imma-

ture seeds of P. caespitosa and P. reclinata. It alsoincludes one archaeological sample. Main descriptiveparameters: Breadth/Length = 0.4–0.6 (76%) or 0.6–0.8 (24%). Length = 4–10 mm. Breadth = 3.5–6.0 mm (77.6%). Depth = 2.5–4.0 mm (86.7%).Totalized dimensions = 0–150 mm3 (89.3%). Ellip-tic (80%). Brown coloured. Apex obtuse (80%). Baseobtuse (60%) or truncate (40%). Surface smooth (80%)or rough (20%), uniform (80%) or wrinkled (20%).Without longitudinal grooves. Micropyle near themiddle of the dorsal face. Ventral raphe U-shaped.Dorsoventrally straight. Not winged.

Group 10: exclusively includes small seeds of P. roe-belenii (from East Asia) and hybrids with other species.Main descriptive parameters: Breadth/Length =0.4–0.6. Length = 4–10 mm. Breadth = 3.5–6.0 mm.Depth = 2.5–4.0 mm (91.8%). Totalized dimen-sions = 0–300 mm3. Oblong. Cream (60%) or Brown(40%) coloured. Apex obtuse. Base truncate.Surface smooth, uniform. Without longitudinalgrooves. Micropyle near the middle of the dorsal face.Ventral raphe U-shaped. Dorsoventrally straight.Not winged.

Group 11: exclusively includes thin immatureseeds of P. dactylifera. Main descriptive parame-ters: Breadth/Length = 0–0.4. Length = 15–32mm. Breadth = 1.0–3.5 mm (83.1%). Depth = 0–2.5 mm (77.5%). Totalized dimensions = 0–150 mm3 (80.6%). Fusiform (50%), cylindric (25%)or oblong (18.8%). Brown coloured. Apex acute(75%). Base obtuse (60%) or truncate (40%). Surfacesmooth (80%) or rough (20%), wrinkled (75%) oruniform (25%). Without longitudinal grooves.Micropyle near the middle of the dorsal face.Ventral raphe U-shaped. Dorsoventrally straight. Notwinged.

Figure 3. Hierarchical tree calculated using the algorithm of Ward with Phoenix type specimens and botanically verifiedmodern seed samples, commercial samples and archaeological and fossil Phoenix seed samples. A (page 93). Cluster I.Small Phoenix species from India and East Asia. Cluster II. Phoenix roebelenii from Mekong river basin. Cluster III.Thin seeds of Phoenix dactylifera from the Near East and North Africa (p.p.). B (page 94). Cluster III. Thin seeds ofPhoenix dactylifera from the Near East and North Africa (p.p.). Cluster IV. Phoenix dactylifera cultivars, and P. atlantica(p.p.). C (page 95). Cluster IV. Phoenix dactylifera cultivars, P. sylvestris, P. iberica, P. canariensis and P. atlantica (p.p.).Cluster V. Phoenix paludosa. Cluster VI. Outgroup. p.p. = pro parte.

▶

92 D. RIVERA ET AL.


Ie

Cluster I (Groups 1 to 8)

Cluster II (Groups 9 to 11)

Cluster III (Group 12)

12

11

10

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5

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1

Figure 3. See caption on previous page.



Cluster III (Groups 14 to 17)

Cluster IV (Group 18)18

17

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14

13

12

Cluster III (Groups 12 to 13)

Figure 3. Continued

94 D. RIVERA ET AL.


24

25

Cluster IV (Groups 18 to 23)

Cluster V (Group 24)

Cluster VI (Group 25)

23

22

21

20

19

18

Figure 3. Continued



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96 D. RIVERA ET AL.


CLUSTER III

This cluster includes modern, archaeological andfossil samples that fall within the variability ofP. dactylifera. See Figures 3A, B, 4 and 5.

Group 12: includes large seeds of P. dactylifera cul-tivars from Spain (40 samples), Baja California(Mexico) (10) and the Near East (10). It also includestwo archaeological samples from Roman Karanis.Main descriptive parameters: Breadth/Length = 0.2–0.6. Length = 19–32 mm. Breadth = 8–12 mm.Depth = 7–12 mm (82.9%). Totalized dimen-sions = 1200–2500 mm3. Oblong (20.5%), cylindrical(54.5%), fusiform (20.3%). Cream (16.8%) or Brown(80%) coloured. Apex obtuse (76.7%) or acute (20%).Sometimes (30%) mucronate. Base truncate (49.4%),obtuse (22.6%), acute (23.7%). Surface smooth (21.4%)or rough (78.6%), wrinkled (36.4%), finely grooved(40.6%) or uniform (23%). Without longitudinalgrooves. Micropyle near the middle of the dorsalface. Ventral raphe V-shaped (60.5%) or U-shaped(33%). Dorsoventrally straight. Occasionally winged(6%).

Group 13: includes the largest seeds of P. dactylif-era (from Baja California, Mexico), one archaeologicalsample from Roman Karanis and the large Eocenefossil seed Phoenicites occidentalis (from Texas, USA)(Berry, 1914). Main descriptive parameters: Breadth/Length = 0.2–0.4. Length = 32–40 mm (88.9%).Breadth = 8–16 mm. Depth = 7–12 mm. Totalizeddimensions = 1850–2500 mm3. Oblong (33.3%),cylindrical (66.7%). Brown coloured (modern seeds).Apex obtuse (88.9%) or truncate (11.1%). Base trun-cate (22.2%), obtuse (44.4%), acute (33.3%). Surfacerough, wrinkled (33.3%), or uniform (66.7%).Without longitudinal grooves. Micropyle near themiddle of the dorsal face. Ventral raphe V-shaped(66.7%) or shallow(33.3%). Dorsoventrally straight.Not winged.

Group 14: almost exclusively includes elongatedand relatively small seeds of P. dactylifera (mainlyfrom West Asia but also from North Africa), and

P. atlantica. It also includes numerous archaeologicalsamples (Neolithic to Middle Ages) and Eocene fossilsfrom Geiseltal named P. hercynica (Mai, 1976). Maindescriptive parameters: Breadth/Length = 0.2–0.4(81.6%). Length = 15–25 mm (84%). Breadth = 6–10 mm (73%). Depth = 5.5–12.0 mm (83.7%). Total-ized dimensions = 300–1850 mm3. Oblong (17.9%),cylindrical (59.1%) or fusiform (23.1%). Cream(20.8%) or brown (37.5%) coloured (modern seeds).Apex obtuse (37.8%) or acute (62.2%). Base truncate(15.3%), obtuse (8.3%), acute (76.7%). Occasionallymucronate (17.5%). Surface smooth (33.3%) or rough(66.7%), wrinkled (70.8%), or uniform (29.2%).Without longitudinal grooves. Micropyle near themiddle of the dorsal face. Ventral raphe V-shaped(16.7%), U-shaped (25%) or shallow (58.3%). Dors-oventrally straight. Not winged.

Group 15: exclusively includes thin seeds of P. dac-tylifera (from the Near East) and several archeologi-cal samples from the Neolithic to Roman period. Maindescriptive parameters: Breadth/Length = 0.2–0.4(81.6%). Length = 19–25 mm (94.3%). Breadth = 6–8 mm (90.5%). Depth = 5.5–7.0 mm (86.1%). Total-ized dimensions = 300–1200 mm3 (94.3%). Oblong(35.7%), cylindrical (57.1%). Cream (7.1%) or brown(35.7%) coloured (modern seeds). Apex obtuse. Basetruncate (12.4%), obtuse (60.7%), acute (27.1%).Surface smooth (71.4%) or rough (28.6%), wrinkled(33.3%) or uniform (66.7%). With longitudinal grooves(21.4%). Micropyle near the middle of the dorsal face.Ventral raphe V-shaped (42.8%), U-shaped (7.1%) orshallow(50%). Dorsoventrally straight or bent (9.1%).Not winged.

Group 16: exclusively includes seeds of P. dactylif-era (from Spain, North Africa and the Near East) andseveral archeological samples from the Neolithic toRoman period. Main descriptive parameters:Breadth/Length = 0.2–0.6. Length = 19–32 mm(91.8%). Breadth = 6–10 mm. Depth = 5.5–12.0 mm.Totalized dimensions = 800–1850 mm3 (79.6%).Ovate–triangular (23.1%), cylindrical (76.9%). Cream

Figure 4. Main types of living Phoenix seed samples (1) Cluster I. Group 1. A, P. loureiroi Europ 101. B, P. loureiroiEurop 105. C, P. loureiroi Europ 13. D, P. loureiroi Europ 4. E, P. loureiroi Rare 6. F, P. loureiroi Sandeman 4. Group 2.G, P. acaulis Europ 106. Group 3. H, P. caespitosa Acaulis 1, I, P. loureiroi Usda 3. G, Group 4. J, P. reclinata Jbo-tanico 1. Group 5. K, P. theophrasti Elaguna 1. Group 6. L, P. andamanensis Olocan 2. M, P. loureiroi (P. hanceana)Riverside 37. N, P. loureiroi USDA 4P. O, P. pusilla Sun 1. Group 7. P, P. rupicola Keni 1. Q, P. rupicola Kpr 4. R,P. rupicola Rare 3. Group 8. S, P. canariensis Cespinardo 3. T, P. canariensis Cespinardo 5. U, P. canariensis Kpr 1.Cluster II. Group 9. V, P. caespitosa (P. arabica) Joe 13. Group 10. W, P. roebelenii Olocau 1. Group 11. X, P. dactyl-ifera Jaravia 5. Cluster III (p.p.). Group 12. Y, P. dactylifera ‘Amir Hajj’ Riverside 8. Z, P. dactylifera ‘Dayri’ River-side 35. AA, P. dactylifera ‘Medjool’ Riverside 12. AB, P. dactylifera ‘Pyarum’ Berlin 2. AC, P. dactylifera ‘Redondos’Mercen 6. AD, P. dactylifera Israel 2. AE, P. dactylifera Olivar 1. AF, P. dactylifera Orisa 5. AG, P. dactylifera SIBC 13.AH, P. dactylifera SIBC 15. AI, P. dactylifera ‘Tenats’ Elche 1. Scale bars in mm; 5-mm grid. Photographs A–AI, JoaquínGarcía.



Figure 4. See caption on previous page.

98 D. RIVERA ET AL.


Figure 5. See caption on next page.



(30.8%) or brown (46.2%) coloured (modern seeds).Apex obtuse (61.5%) or acute (37.9%). Base oblique(81.3%). Surface smooth (46.2%) or rough (53.8%),wrinkled (55.5%), or uniform (44.5%). Without longi-tudinal. Micropyle near the middle of the dorsal face.Ventral raphe V-shaped (30.7%), or U-shaped (69.3%).Dorsoventrally straight. Not winged.

Group 17: almost exclusively includes archaeologi-cal, cylindrical but dorsoventrally flattened seedsfrom Iron Age Raybun (South Arabia) and one sampleof P. dactylifera from Baja California (Mexico). Maindescriptive parameters: Breadth/Length = 0.2–0.6.Length = 15–25 mm. Breadth = 6–10 mm. Depth = 4–7 mm. Depth/breadth < 0.75. Totalized dimen-sions = 300–1850 mm3. Oblong (10%), cylindrical(90%). Brown coloured (modern seeds). Apex obtuse.Base obtuse. Surface smooth, wrinkled (10%), oruniform (90%). Without longitudinal grooves. Micro-pyle near the middle of the dorsal face. Ventralraphe shallow. Dorsoventrally straight. Not winged.

CLUSTER IV

This cluster includes somewhat rounded seeds ofP. dactylifera, P. atlantica, P. iberica, P. sylvestris anda few archaeological samples and one Miocene fossilsample.

See Figures 3B, C and 5.Group 18: includes seeds of P. dactylifera (from

Spain, North Africa and the Near East), severalhybrids of P. dactylifera, two samples of P. atlanticafrom Cabo Verde, two of P. senegalensis, one ofP. canariensis var. macrocarpa collected by HermannWildpret in Tenerife, two samples from Turkeylabelled by Professor Esener as P. theophrasti and onearcheological sample from Neolithic Takarkori(Libya). Main descriptive parameters: Breadth/Length = 0.4–0.6 (93.9%). Length = 15–25 mm(91.2%). Breadth = 6–10 mm. Depth = 5.5–12.0 mm.Totalized dimensions = 800–1850 mm3. Oblong.Cream (30.2%) or brown (69.8%) coloured (modern

seeds). Apex obtuse. Base truncate (36.5%), obtuse(58.6%). Surface smooth (29.4%) or rough (70.6%),wrinkled (51.9%) or uniform (48.1%). With longitudi-nal grooves (19.8%). Micropyle near the middle of thedorsal face. Ventral raphe V-shaped (52.8%),U-shaped (36.1%) or shallow (11.1%). Dorsoventrallystraight or bent (1.7%). Rarely winged (1.5%).

Group 19: includes the seeds of P. sylvestris (fromIndia) and the type icon of this species, the type ofP. iberica, several samples of P. dactylifera from Spainand Baja California (Mexico) and the whole sample ofMiocene fossil seeds named P. bohemica (Buzek,1977). Main descriptive parameters: Breadth/Length = 0.4–0.8. Length = 15–25 mm (81.2%).Breadth = 8–12 mm. Depth = 7–12 mm. Totalizeddimensions = 800–2500 mm3. Oblong (37.7%), ellip-soid (52.9%). Cream (64.6%) or brown (69.8%) col-oured (modern seeds). Apex obtuse. Base truncate(42.1%), obtuse (55.9%). Surface smooth (9.9%) orrough (88.1%), wrinkled (28.2%), or uniform(71.8%). With longitudinal grooves (57.7%). Micro-pyle near the middle of the dorsal face. Ventral rapheV-shaped (19.2%), U-shaped (80.8%). Dorsoventrallystraight. Not winged.

Group 20: exclusively includes seeds of P. dactylif-era (from Spain, Baja California, North Africa and theNear East) and three archeological samples, two fromRoman Karanis and one from Iron Age Tayma. Maindescriptive parameters: Breadth/Length = 0.2–0.6.Length = 19–25 mm (83.6%). Breadth = 8–12 mm.Depth = 7–12 mm (92.2%). Totalized dimen-sions = 1200–2500 mm3 (94%). Oblong (92.4%).Cream (30%) or brown (60%) coloured (modern seeds).Apex obtuse (92.2%). Frequently mucronate(29.6%). Base truncate (39.2%), obtuse (44.3%), acute(16.7%). Surface smooth (13.3%) or rough (86.7%),wrinkled (76.7%), or uniform (23.3%). Without lon-gitudinal grooves. Micropyle near the middle of thedorsal face. Ventral raphe V-shaped (56.7%),U-shaped (43.3%). Dorsoventrally straight. Rarelywinged (4.9%).

Figure 5. Main types of living Phoenix seed samples (2) Cluster III (p.p.). Group 14. A, P. atlantica Cabo Verde 1. B,P. dactylifera ‘Abada’ Riverside 7. C, P. dactylifera ‘Deglet Nour’ Deglet 1. D, P. dactylifera ‘Khisab’ Riverside 34.E, P. dactylifera ‘Khudari’ Arabia 3. F, P. dactylifera Libya 1. Group 15. G, P. dactylifera ‘Khadrawy’ Riverside 15. H,P. dactylifera ‘Khir’ Riverside 4. Group 16. I, P. dactylifera ‘Bentamoda’ Riverside 6. J, P. dactylifera ‘Halawy’ River-side 25. K, P. dactylifera Fuentes 3. Cluster IV. Group 18. L, P. atlantica Cabo Verde 2. M, P. atlantica Cabo Verde 3.N, P. canariensis var. porphyrococca Lisboa 1. O, P. canariensis var. porphyrococca Riverside 1. P, P. dactylifera ‘Barhee’Barhee. Q, P. dactylifera ‘Zahidi’ Riverside 36. R, P. dactylifera SIBC 18. S, P. dactylifera × P. iberica IslaPlana 1. T,P. dactylifera × P. iberica SIBC 23. U, P. theophrasti ‘Datça’ Turquia 2. Group 19. V, P. dactylifera Fuentes 1. W, P. dac-tylifera Parque 1. X, P. sylvestris ‘Robusta’ Keni 6. Y, P. sylvestris Rare 2. Z, P. sylvestris Riverside 42. AA, P. sylvestrisRiverside A1. Group 20. AB, P. dactylifera ‘Badrayah’ Riverside 18. AC, P. dactylifera ‘Deglet Beida’ Riverside 2. AD,P. dactylifera ‘Hayani’ Riverside 30. AE, P. dactylifera Alcudia 1. AF, P. dactylifera SIBC 14. Group 21. AG, P. sylves-tris × P. pusilla Keni 4. Group 22. AH, P. dactylifera ‘Asrashi’ Riverside 32. Cluster V. Group 24. AI, P. paludosaRare 5. Scale bars in mm. 5-mm grid. Photographs A–AI, Joaquín García.

100 D. RIVERA ET AL.


Group 21: almost exclusively includes seeds ofP. canariensis (from Canary Islands, Spain) compris-ing the type icon of P. canariensis and seeds collectedby Hermann Wildpret in Tenerife and now in FI, andtwo P. sylvestris × P. pusilla hybrids. It also includesthe single type specimen of the sample of Miocenefossil seeds named P. bohemica (Buzek, 1977). Maindescriptive parameters: Breadth/Length = 0.6–0.8(90.8%). Length = 10–19 mm. Breadth = 8–12 mm.Depth = 7–12 mm. Totalized dimensions = 800–1850 mm3. Elliptical. Cream (20.6%) or brown(79.4%) coloured (modern seeds). Apex obtuse. Basetruncate (26.1%), obtuse (73.3%). Surface smooth(78.9%) or rough (21.1%), uniform. With longitudi-nal grooves. Micropyle near the middle of the dorsalface. Ventral raphe U-shaped. Dorsoventrallystraight. Not winged.

Group 22: almost exclusively includes seeds ofP. dactylifera (from Spain and the Near East) compris-ing the type icon of the species and original material ofP. dactylifera var. adunca Becc. (now in FI). It alsocontains the sample of seeds and dates bought byA. Chevalier in the market of Praia (Cabo Verde)and named P. atlantica (now in P). Main descriptiveparameters: Breadth/Length = 0.2–0.6 (93.8%).Length = 15–25 mm (94.3%). Breadth = 6–12 mm.Depth = 7–12 mm (85.3%). Totalized dimen-sions = 800–2500 mm3 (90.6%). Ovate–triangular.Cream (40%) or brown (60%) coloured (modern seeds).Apex obtuse (59.1%) or acute (40.9%). Often mucro-nate (38.4%). Base truncate (42.3%), obtuse (37.9%),acute (19.3%). Surface smooth (6.7%) or rough(92.3%), wrinkled (37.8%), finely grooved (14.2%) oruniform (48%). Without longitudinal grooves.Micropyle near the middle of the dorsal face. Ventralraphe V-shaped (33.3%), or U-shaped (66.7%). Oftendorsoventrally bent (22.9%). Not winged.

Group 23: exclusively includes seeds of P. dactylif-era var. costata Becc. (from Spain, North Africa andBaja California). Main descriptive parameters:Breadth/Length = 0.4–0.8. Length = 15–25 mm(87.8%). Breadth = 10–12 mm (88.9%). Depth = 7–12 mm. Totalized dimensions = 1200–2500 mm3

(94.4%). Ovate–triangular (80%), elliptical (15.6%).Cream (33.3%) or brown (66.7%) coloured (modernseeds). Apex obtuse (80%) or acute (20%). Occa-sionally mucronate (17.8%). Base obtuse (64.4%),acute (33.3%). Surface rough, wrinkled (33.3%), oruniform (66.7%). Without longitudinal grooves.Micropyle near the middle of the dorsal face. Ventralraphe V-shaped (33.3%), U-shaped (33.3%) or shallow(33.3%). Dorsoventrally straight. Winged (88.9%).

CLUSTER V

This cluster includes exclusively an extremely homo-geneous group of small rounded seeds of P. paludosa

from the littorals of India and South-East Asia. Themost typical character is the basal position of themicropyle. See Figures 3C and 5.

Group 24: exclusively includes seeds of P. paludosa(from mangroves of South-East Asia). Main descrip-tive parameters: Breadth/Length = 0.6–1. Length =4–10 mm. Breadth = 3.5–8 mm. Depth = 2.5–5.5 mm. Totalized dimensions = 150–800 mm3.Hemispherical. Blackish (81.7%) or greyish(18.3%) coloured. Apex obtuse. Base obtuse.Surface smooth, uniform. Without longitudinalgrooves. Micropyle basal. Ventral raphe shallow.Dorsoventrally straight. Not winged.

CLUSTER VI

This last cluster includes the largely variable indimensions but otherwise uniform outgroup withglobose seeds of Nannorrhops, Euterpe, Livistona andWashingtonia. See Figure 3C.

Group 25: outgroup, exclusively includes seeds ofNannorrhops, Euterpe, Livistona and Washingtonia.Main descriptive parameters: Breadth/Length = 0.6–1.0. Length = 4–15 mm. Breadth = 3.5–16.0 mm.Depth = 2.5–12.0 mm. Totalized dimensions = 0–2500 mm3. Globose. Brown coloured. Apexobtuse. Base obtuse. Surface smooth, uniform.Without longitudinal grooves. Micropyle basal.Ventral raphe shallow. Dorsoventrally straight. Notwinged.

DISCUSSIONOVERALL PATTERNS OF GROUPING AND MORPHOTYPES

IN MODERN SPECIES

In general, each of the groups described correspondsto a characteristic morphotype. Some species havemorphologically homogeneous seeds and all samplesstudied of the same species are included in a singlemorphotype. By contrast, other species show a greatmorphological variability in their seeds, which areintegrated into different groups, corresponding to dif-ferent morphotypes. Phoenix dactylifera seeds havethe highest variability (Tables 6 and 7).

Cluster IPhoenix loureiroi was lectotypified with the specimenPierre 4832 (FB-I) from Mount Kuang Repen in Cam-bodia (Barrow, 1998), but it only consists of leafletsand flowers. Most samples of P. loureiroi are in andform the majority of group 1 (Cluster I) (Table 6).However, a few, probably of hybrid origin and par-ticularly those named P. hanceana from Hong Kongand the Philippines (now a synonym of P. loureiroi),are in groups 3 and 6 (Cluster I). No regularpattern was detected for seed morphology variation



Tab

le7.

Su

mm

ary

ofth

ese

edm

orph

olog

yof

Ph

oen

ixd

acty

life

raan

dit

sh

ybri

ds.N

um

bers

afte

rn

ames

ofth

esp

ecie

sre

fer

tom

orph

otyp

es/g

rou

ps,1

2to

17be

lon

gto

Clu

ster

III

and

18to

23be

lon

gto

Clu

ster

4

Ch

arac

ters

/st

ates

P.d

acty

life

ra12

P.d

acty

life

ra13

P.d

acty

life

ra14

P.d

acty

life

ra15

P.d

acty

life

ra16

P.d

acty

life

ra17

P.d

acty

life

ra18

P.d

acty

life

ra19

P.d

acty

life

ra20

P.d

acty

life

ra22

BTy

peP.

dac

tyli

fera

22C

adu

nca

P.d

acty

life

ra23

cost

ata

P.d

acty

life

ra×

P.ca

nar

18P.

dac

tyli

fera

×P.

iber

ica

18

B/L

0.2–

0.6

0.2–

0.4

0.2–

0.6

0.2–

0.4

0.2–

0.4

0.2–

0.6

0.4–

0.6

0.4–

0.8

0.2–

0.6

0.4–

0.6

0.2–

0.6

0.4–

0.8

0.4–

0.6

0.4–

0.6

Lm

m19

–32

32–3

915

–32

19–3

219

–32

19–3

215

–25

15–2

519

–25

15–2

515

–25

15–2

510

–19

15–2

5

Bm

m8–

1210

–12

6–10

6–8

6–10

8–12

6–10

8–12

8–12

10–1

26–

128–

126–

106–

10

Dm

m5.

5–15

7–17

5.5–

154–

75.

5–15

4–7

5.5–

157–

157–

155.

5–12

5.5–

127–

157–

155.

5–12

TD

mm

312

00–2

500

1850

–250

080

0–18

5080

0–18

5080

0–18

5080

0–18

5080

0–18

5080

0–18

5080

0–25

0012

00–1

850

800–

2500

800–

2500

300–

1200

800–

1850

Ou

tlin

eC

ylin

dric

,ob

lon

gC

ylin

dric

Cyl

indr

ic,

oblo

ng

Cyl

indr

icC

ylin

dric

Obl

ong

Obl

ong

Ell

ipti

cO

blon

gO

vate

–tr

ian

gula

rO

vate

–tr

ian

gula

rO

vate

–tr

ian

gula

r,el

lipt

ic

Obl

ong

(ell

ipti

c)O

blon

g

Col

our

Bro

wn

(cre

am)

Bro

wn

Bro

wn

,cr

eam

Bro

wn

(cre

am)

Bro

wn

,cr

eam

Bro

wn

Bro

wn

,cr

eam

Bro

wn

(cre

am)

Bro

wn

(cre

am)

Cre

amB

row

n,

crea

mB

row

n,

crea

mB

row

n(c

ream

)B

row

n

Ape

xO

btu

se(a

cute

)O

btu

seA

cute

(obt

use

)O

btu

seO

btu

se(a

cute

)O

btu

se,

tru

nca

teO

btu

seO

btu

seO

btu

seA

cute

Acu

te(o

btu

se)

Obt

use

(acu

te)

Obt

use

Obt

use

Ape

xm

ucr

onat

eF

requ

ent

Not

Som

etim

esN

otN

otN

otN

otS

omet

imes

Fre

quen

tA

lway

sS

omet

imes

Som

etim

esN

otN

ot

Bas

eTr

un

cate

(obt

use

,ac

ute

)

Acu

teA

cute

(tru

nca

te)

Acu

te(t

run

cate

,ob

tuse

)

Obl

iqu

e(t

run

cate

,ac

ute

)

Tru

nca

te,

obtu

seO

btu

seO

btu

se(t

run

cate

)O

btu

se(t

run

cate

,ac

ute

)

Tru

nca

teO

btu

se(t

run

cate

)O

btu

se(a

cute

)Tr

un

cate

(obt

use

)O

btu

se

Bas

em

ucr

onat

eS

omet

imes

Not

Fre

quen

tN

otF

requ

ent

Not

Som

etim

esN

otN

otN

otS

omet

imes

Not

Not

Not

Su

rfac

eR

ough

(sm

ooth

)R

ough

Sm

ooth

,ro

ugh

Sm

ooth

,ro

ugh

Sm

ooth

(rou

gh)

Sm

ooth

Rou

gh(s

moo

th)

Rou

gh(s

moo

th)

Rou

ghR

ough

Rou

gh(s

moo

th)

Rou

ghR

ough

(sm

ooth

)R

ough

Tran

sver

sepr

oces

ses

Wri

nkl

ed,

fin

ely

groo

ved

Un

ifor

mW

rin

kled

,u

nif

orm

Wri

nkl

ed,

un

ifor

mW

rin

kled

,u

nif

orm

Wri

nkl

edW

rin

kled

,u

nif

orm

Wri

nkl

ed,

un

ifor

mW

rin

kled

Fin

ely

groo

ved

(wri

nkl

ed)

Wri

nkl

ed(u

nif

orm

,fi

nel

ygr

oove

d)

Un

ifor

m(w

rin

kled

)U

nif

orm

Wri

nkl

ed(u

nif

orm

)

Lon

gitu

din

algr

oove

sN

otN

otN

otN

otN

otN

otN

otS

omet

imes

Not

Not

Not

Not

Not

Not

Mic

ropy

leC

entr

alC

entr

alC

entr

alC

entr

alC

entr

alC

entr

alC

entr

alC

entr

alC

entr

alC

entr

alC

entr

alC

entr

alC

entr

alC

entr

al

Ven

tral

furr

owV

-sh

aped

(U-s

hap

ed)

V-s

hap

edS

hal

low

(V-s

hap

ed)

V-s

hap

ed,

shal

low

U-s

hap

ed,

V-s

hap

edU

-sh

aped

V-s

hap

ed(U

-sh

aped

)V

-sh

aped

(U-s

hap

ed)

V-s

hap

ed,

U-s

hap

edU

-sh

aped

(V-s

hap

ed)

U-s

hap

ed,

V-s

hap

edU

-sh

aped

,V

-sh

aped

,sh

allo

w

Sh

allo

w(U

-sh

aped

)U

-sh

aped

Dor

so-v

entr

alcu

rvat

ure

Not

Not

Not

Som

etim

esN

otN

otN

otN

otN

otN

otF

requ

ent

Not

Not

Not

Win

gsN

otN

otN

otN

otN

otN

otN

otN

otN

otN

otN

otF

requ

ent

Not

Som

etim

es



among different varieties recognized in this species byhorticulturists or Barrow (1998).

For the type of P. andamanensis, Barrow (1998)named Ellis 14189 (K), which is labelled as the holo-type and contains numerous desiccated fruits andseeds (Fig. 6A). It is in group 1 (Cluster I) (Table 6)with numerous P. loureiroi samples. The ruminateendosperm (Barrow, 1998) was verified in this sampleand in one sample of P. andamanensis from Rutland(Andaman) Rogers (FI-B); both show deep brownrumina in transverse section. Weighted neighborjoining shows as the closest modern sample P. lourei-roi from Batanes Island (Philippines) (type specimenof P. hanceana var. philippinensis Becc., FI-B)(Fig. 6B) (62% in 5000 bootstraps). No molecular evi-dence was presented for this species by Pintaud et al.2010, 2013). As the character of rumination can breakdown and, in a few recorded species (e.g. Nypa fruti-cans Wurmb and Ptychococcus paradoxus (Scheff.)Becc.), seeds can be homogeneous or ruminate, asso-ciated with the low resolution obtained from P. lourei-roi; further studies are necessary to ascertain thestatus of P. andamanensis as a species. The specimenlabelled in the collection of Tomás Font as P. anda-

manenis (OLOCAN 02) falls within the variability ofP. loureiroi and the studied seeds are not ruminate.

For P. pusilla. Barrow (1998) mentioned Gaertner(1788–1791: fig. 9) as a lectotype. The icon depicts onefruit and one seed (Fig. 7A). The seed falls in group 2(Cluster I) (P. pusilla A, Table 6) with P. zeylanica,which Barrow (1998) and Govaerts et al. (2011)included in P. pusilla, and with several P. acaulissamples. Weighted neighbor joining shows as theclosest sample the icon of P. zeylanica from Trimen(1898) (Fig. 7B) (TRIMCEYHAN) (32% in 5000 boot-straps). Barrow (1998) typified P. zeylanica withThwaites C.P. 3172 (K), which contains no seeds.Phoenix farinifera, also a synonym of P. pusillaaccording to Barrow (1998) and Govaerts et al. (2011),was typified with plate 74 of Roxburgh (1796) byBarrow (1998) and the seed shown in this icon(Fig. 8A) is in group 6 (Cluster I) (P. pusilla B,Table 6) with two modern samples of P. pusilla (SUN03 and SUN 01) and several from P. loureiroi withIron Age Raybun archaeological samples and anEocene fossil labelled Serenoa carbonaria (Table 8).Weighted neighbor joining shows as the closestsample P. pusilla (SUN 03) (Fig. 8B) (59% in 5000

Figure 6. Phoenix andamanensis S.Barrow. A, Holotype, Ellis 14189 (K). B, Phoenix loureiroi from Batanes Island(Philippines) (type specimen of P. hanceana var. philippinensis Becc., FI-B). Scale bars in mm. B, photograph Teresa Egea.

Figure 7. Phoenix pusilla Gaertn. (p.p.) A, Phoenix pusilla Gaertn. Lectotype in Gaertner (1788–1791): table 9. B,Phoenix zeylanica Trimen. 1. Trimen (1898: plate 95).



bootstraps). Therefore, it seems that P. pusilla is poly-morphic with regard to seed morphology. This poly-morphism is not found in the homogeneous clusterobtained for the four samples of the species studied byPintaud et al. (2010).

Barrow (1998) mentioned plate 273 in Roxburgh(1820) as the type of P. acaulis. This plate includes animage of a seed (Fig. 9A). It falls in group 2(Cluster I) with several P. acaulis samples (Table 6),and the types of P. pusilla and P. zeylanica. Weightedneighbor joining shows two P. acaulis from B & TSeeds (ACAULISB&T_1 and 3) (Fig. 9B) (53% in 5000bootstraps) as the closest modern samples. Pintaudet al. (2010) studied two samples cultivated in theUSA, seemingly from seeds collected in India, and theunrooted neighbor joining tree based on simplesequence repeat (SSR) markers clustered thesesamples with P. caespitosa and P. sylvestris, in con-trast to our results.

According to Barrow (1998), the lectotype of P. rec-linata is an icon published in Jacquin (1801: plate 24).The seed shown in this icon (Fig. 10A) falls in group 4(Cluster I) with several modern samples of P. recli-nata (Fig. 10B) and archaeological samples from NorthAfrica and West Asia, including Bronze Age casts ofdate seeds from Ar Raqlah (Yemen). Several samplesthat are probable hybrids of P. reclinata with otherspecies fall in groups 1, 3 and 6 (Cluster I). Pintaudet al. (2010) studied numerous samples from differentEast African countries (but not from West and SouthAfrica), which cluster with a bootstrap value > 70%.These appear close to the P. loureiroi cluster, but alsowith low bootstrap values.

The holotype of P. theophrasti is in the herbariumGreuter (PAL-Gr), but an isotype with numerousfruits and seeds is at K. Several seed samples fromthe classical locality of Vai (Crete, Greece) and onefrom Gölköy (Turkey) fall in group 5 (Cluster I)

Figure 8. Phoenix pusilla Gaertn. (p.p.) A, Phoenix farinifera Roxb. Holotype?, Roxburgh (1796: table 74 ). B, Phoenixpusilla (SUN 03), 5-mm grid. B, photograph Joaquín García.

Table 8. Ancestral states according to the morphology of the Tertiary fossil seeds analysed. For the purpose of comparisoncolour is not analysed because it is lost or strongly changed during fossilization and mucro is not because of the fragilityof this appendix. For the purpose of comparison Serenoa repens (W.Bartram) Small, seeds are described

Characters / statesPhoenixbohemica Phoenix hercynica

Phoenicitesoccidentalis

Serenoacarbonaria Serenoa repens

B/L 0.4–0.8 0.2–0.4 0.2–0.4 0.4–1 0.5–0.6L mm 10–25 19–25 32–39 4–15 17–20B mm 8–10 3.5–6 12–16 3.5–8 9–11D mm 7–(17) 7–(17) 7–(17) 4–7 9–11D/B 0.85–0.9 0.95–1.5 0.95–1.5 0.85–0.9 0.9–1.1TD mm3 800–1850 800–1200 1850–2500 150–800 1300–2500Outline Elliptic Cylindric Oblong Elliptic, globose,

ovate–triangularElliptic

Apex Obtuse Acute Obtuse Obtuse Obtuse (acute)Base Obtuse Acute Obtuse Truncate ObtuseSurface Rough Rough Rough Smooth SmoothTransverse processes Wrinkled Wrinkled Wrinkled Uniform UniformLongitudinal grooves Not? Not? Not? Not? NotMicropyle Central Central Central Central BasalVentral furrow U-shaped U-shaped Shallow U-shaped NotDorso-ventral curvature Not Not Not Not NotWings Not Not Not Not Not



(Table 6) with a waterlogged date seed recovered fromNeolithic Atlit-Yam (Israel) (Fig. 11A). Weightedneighbor joining shows as the closest living relativesto the Neolithic seed two samples of P. theophrasti(66% in 5000 bootstraps), from Vai and Gölköy(Fig. 11B, C). Seeds from Datça and one sample fromGölköy (both Turkey, but the last probably misla-belled for Datça) labelled P. theophrasti fall ingroup 18 (Cluster IV) (Table 6), with numerousP. dactylifera cultivars suggesting these are notP. theophrasti, but of hybrid origin, or simply thatthese are feral P. dactylifera. Pintaud et al. (2010)showed that samples of this species from Crete andTurkey fell in the same distinct cluster of theunrooted neighbor joining tree based on SSR markerswith a bootstrap value of 84%, coinciding with ourresults for the Crete and Gölköy samples.

For P. rupicola, Barrow (1998) mentioned as origi-nal material India, West Bengal, Sivoka, Teestavalley, February 1867, Herb. Sikkimense T. Andersons.n. [CAL (sterile material), K (not yet in the digitalherbarium)]. Several modern samples of this species

are the only members of group 7 (Cluster 1)(Table 6). Pintaud et al. (2010) found four samples ofthis species from India and Bhutan in the samedistinct cluster of the unrooted neighbor joining treebased on SSR markers with a bootstrap value of 92%,coinciding with our results and underlining the iso-lation of this taxon.

According to Barrow (1998), the lectotype ofP. caespitosa is the specimen collected in Somalia,‘Scorasar’ valley, 1 July 1924, Puccioni & Stefanini672 (738) (FT) with a female inflorescence and a leaffragment, but with no seeds. Phoenix arabica wastreated as a synonym by Barrow (1998). We could notanalyse seeds from East Africa (Somalia and Dji-bouti), although two specimens from cultivated plants(group 3) may belong to this species. A herbariumspecimen of P. arabica (FAIRCHILD 1) (Fig. 12A)from the Fairchild Tropical Botanical Garden(Florida, USA) from a palm introduced there fromSaudi Arabia falls in group 8 (Cluster I) (Table 6)with several P. canariensis samples, one P. loureiroisample and three archaeological samples. Weighted

Figure 9. Phoenix acaulis Roxb. A, neotype Roxburgh (1820: table 273). B, sample from north-east India(ACAULISB&T_1). Scale bars in mm. B, photograph Diego Rivera.

Figure 10. Phoenix reclinata Jacq. A, lectotype Jacquin (1801: table 25). B, Jardín Botánico (Valencia, Spain). 5-mm grid.B, photograph Joaquín García.



neighbor joining shows a Pleistocene sample fromKharga Oasis (Egypt) (50% in 5000 bootstraps)(Fig. 12B) as the closest specimen. However, as thislast material is carbonized, further analyses will berequired with experimental charring of modern seeds.Several, immature P. caespitosa (P. arabica) seedsfrom Yemen form group 9 (Cluster II). Pintaud et al.(2010) showed that the only sample of this speciesfrom Somalia fell close to the clusters of P. acaulisand of P. sylvestris in the unrooted neighbor joiningtree based on SSR markers with a bootstrap value> 70%. Pintaud et al. (2013) showed that samples ofthis species fell in an early branching position in thehaplotype network reconstruction based on plastidsequence data related to the ‘Phoenix dactyliferaclade’ and to the branch of P. reclinata. Furtherstudies with additional samples will be required toclarify the status of this taxon.

Cluster IIThe holotype specimen of P. roebelenii is sterile(Barrow, 1998), and thus seeds could not be analysed.Modern seed samples from different origins form thedistinct group 10 (Cluster II) (Table 6). Seeds aresmall and thin and have a widely open ‘U’-shapedventral raphe (Fig. 4W). Pintaud et al. (2010) showedthat four samples of cultivated specimens of thisspecies fell in the same distinct cluster of theunrooted neighbor joining tree based on SSR markerswith a bootstrap value of 79%, coinciding with ourresults and underlining the isolation of this taxon.

Clusters III and IVThe type specimen of P. iberica (herbarium MUB)includes seeds (IBTYPE_1) that fall in group 19(Cluster IV) with several P. dactylifera/P. ibericasamples from south-eastern Spain, P. sylvestris

Figure 11. Phoenix theophrasti Greuter. A, one complete waterlogged date kernel PPNC (6000–5200 BC) found inAtlit-Yam at structure 20 (Kislev et al., 2004). B, seeds from Gölköy (Turkey) Elaguna 02. C, seeds from Vai (Crete, Greece)Europ 07. Scale bars in mm. 5-mm grid. A, photograph Anat Hartmann-Shenkman; B–C, photographs Joaquín García.

Figure 12. Phoenix caespitosa Chiov. (P. arabica Burrett). A, PLEI_KHARGA (Gardner, 1935). B, Fairchild 1. Scale barsin mm. B, photograph Diego Rivera.



samples including the type and the whole sample often seeds from Miocene P. bohemica (FOSSMIOCBOHEM1-10). Thus, distinction of this speciesis not achieved, but the analysis places P. iberica in agroup sharing numerous ancestral states (Fig. 3C,Table 6). No molecular evidence was presented forthis species by Pintaud et al. 2010, 2013).

Moore & Dransfield (1979) designated plates 22 to25 of Rheede (1682), depicting Katou-Indel, as thelectotype of P. sylvestris. Plate 25 includes an image ofa seed (Fig. 13A), which falls in group 19(Cluster IV) (Table 6) with all the modern samples ofP. sylvestris, several P. dactylifera/P. iberica samplesfrom south-eastern Spain (including the holotype ofP. iberica) and the whole sample of ten seeds fromMiocene P. bohemica (FOSS MIOCBOHEM1-10).Weighted neighbor joining shows as the closest speci-mens a pair of P. sylvestris samples from Darjeeling(India) (KENI 5 and 6) (Fig. 13B, C) (44% in 5000bootstraps). Molecular evidence was presented forthis species by Pintaud et al. 2010, 2013), but thecluster had a bootstrap value < 70%.

Moore (1971) designated Chabaud (1882): figs 66–68 as the lectotype of P. canariensis. Particularlyinteresting for the present study is Chabaud (1882):fig. 68, which depicts a seed (Fig. 14A) and presentsfurther implications for the taxonomy of the species(Rivera et al., 2013b). This seed (CHABATYPE) fallsin group 21 (Cluster VI) with the sample ofP. canariensis seeds sent from Tenerife by HermannWildpret to Odoardo Beccari in December 1886 (FI)(FIWILDP_1) (Fig. 14B), several modern samplesfrom the Canary Islands and the Iberian Peninsula(P. canariensis B, Table 6), two hybrids and the typespecimen of the sample of ten seeds from MioceneP. bohemica (FOSS MIOCBOHEM1-10). Thus, spe-cific distinction is supported and the analysis placesP. canariensis in a group sharing numerous ancestralstates (Fig. 3C, Table 6). However four small-sizedseed samples from cultivated P. canariensis (Espi-nardo, Murcia, Spain) fall in group 8 (Cluster I)(P. canariensis A, Table 6) with four date seeds recov-ered from a Guanche religious offering site at Gara-jonay (Canary Islands, Spain) (Fig. 14C) (Morales,

Figure 13. Phoenix sylvestris L. A, lectotype, Rheede (1682: plate 25). B, sample from India (Keni 05). C, sample fromIndia (Keni 06). 5-mm grid. B, C, photographs Joaquín García.

Figure 14. Phoenix canariensis H.Wildpret. A, lectotype, Chabaud (1882: fig. 68). B, Wildpret (FI). C, archaeologicalmaterial from Garajonay. B, photograph Teresa Egea. C, photograph Jacob Morales.



Navarro & Rodríguez, 2011), other archaeologicalsamples from Roman Karanis (Egypt) and Chalco-lithic Tepe Gaz Tavila (Iran) and one modern sampleof P. caespitosa (P. arabica). It is important to notethis dimorphism in samples of P. canariensis, particu-larly when the only archaeological sample studied isnot in the group of the type of the species. However,it is not surprising because P. canariensis shows ahigh degree of morphological and molecular variabil-ity within and between each one of the seven CanaryIslands (P. Sosa, pers. comm.). Pintaud et al. (2010)showed that four samples of cultivated specimens ofthis species fell in the same distinct cluster of theunrooted neighbor joining tree based on SSR markerswith a bootstrap value of 99%, underlining the isola-tion of this taxon.

Phoenix atlantica was typified by Chevalier 45839(P) from Algodeiro (Sal Island, Cabo Verde) (Barrow,1998). However, the two sheets under this number atP seem to contain more than one specimen and noseeds. Phoenix seed samples from Cabo Verde showhigh morphological variability, and attribution toeither P. dactylifera or P. atlantica is difficult. Thesedo not form a distinct group. The type specimen ofP. dactylifera var. adunca from Algeria (FI-B)(FIBECC_2) (Fig. 15A) falls in group 22(Cluster IV) (Table 6) with a sample from Praiamarket (São Tiago island, Cabo Verde) collected byChevalier (P) (Fig. 15B), which is original material ofP. atlantica, and two fruit samples bought at themarket of Mindelo by J. Meseguer (São Vicente island(Cabo Verde) (Fig. 15C), the type icon of P. dactyliferaand several P. dactylifera cultivars from Spain, twofrom Socotra and one from West Asia (P. dactylifera‘Asrashi’). The seeds are small and often regularlydorsoventrally bent. Other samples from Cabo Verde

fall in group 18 (Cluster IV). Exhaustive samplingin the ensemble of Cabo Verde islands will berequired to delimit the morphology of seeds withinthis species clearly. Pintaud et al. (2013) included twosamples of this species in the ‘Phoenix dactyliferaclade’ based on plastid sequence data.

Moore & Dransfield (1979) designated Kaempfer(1712): plates 1 and 2 depicting Palma hortensis mas etfoemina as the lectotype of P. dactylifera. Plate 2includes an image of a seed (Fig. 16A). This seed(KAEMPTYPE_1315) falls in group 22 (Cluster IV)(P. dactylifera 22B Type, Table 7). Weighted neighborjoining shows as the closest specimen a P. dactyliferasample from Ricabacica (south-eastern Spain)(Fig. 16B) (64% in 5000 bootstraps). Modern samplesof this species are predominant in Clusters III andIV, and several immature seeds fall in Cluster II.This species shows the highest variability in terms ofseed shape and dimensions in Phoenix and it is relatedwith at least two different sets of ancestral states(Fig. 3B, C, Tables 7 and 8). At least 12 differentmorphotypes can be distinguished (Table 7). This couldbe interpreted as a consequence of different selectivepressures during domestication, an indicator of poly-phyletic origin of P. dactylifera or both. Terral et al.(2012), using a different methodology, recognized tenmorphotypes. Although the methodology employedand the analysed samples are different, there is in parta correspondence between our groups (12–20 and22–23) and those morphotypes of Terral et al. (2012):MT1 with 17 (doubtful); MT2 with 22 (doubtful); MT3with 14; MT4 with 19 and 18 p.p.; MT5 with 12; MT6with 15 p.p. and 18 p.p.; MT7 with 15 p.p.; MT8 with16 (doubtful); MT9 with 18 p.p.; and MT10 with 20.Pintaud et al. (2010) studied 20 samples from differentcountries that clustered with a bootstrap value > 70%.

Figure 15. Phoenix atlantica A.Chev. and P. dactylifera var. adunca O.Becc. A, P. dactylifera var. adunca from Algeria,holotype (FI-B) (FIBECC_2). B, P. atlantica. Sample collected by Chevalier in the market of Praia (Cabo Verde) (P). C,P. atlantica. São Vicente island (Cabo Verde). Scale bars in mm. A, photograph Teresa Egea; B, photograph Muséumnational d’Histoire naturelle, Paris; C, photograph Diego Rivera.



These appear close to the P. theophrasti and P. canar-iensis clusters, but also with low bootstrap values.Pintaud et al. (2013) included samples of this specieswith P. atlantica and P. sylvestris in the ‘Phoenix dac-tylifera clade’ based on plastid sequence data.

Phoenix dactylifera var. adunca. The type specimenfrom Algeria (FI-B) consists of three seeds(FIBECC_2) (Fig. 15A) and falls in group 22(Cluster IV) with three modern samples from SãoVicente and São Tiago islands (Cabo Verde) (P. atlan-tica/P. dactylifera) and one from West Asia (P. dactyl-ifera) (P. dactylifera 22C adunca, Table 7).

Phoenix dactylifera var. costata. The type specimenfrom Valencia (Spain) (FI-B) (FIBECC_3) falls ingroup 23 (Cluster IV) with two modern samplesfrom Santomera (Murcia, Spain) and Baja California(Mexico). Seeds are small and often regularly winged(Table 7).

Cluster VThe lectotype of P. paludosa, is an unpublished plateunder No. 1193 of Roxburgh’s Flora Indica (K)(Barrow, 1998). Modern seed samples of P. paludosaform a distinct Cluster V (group 24) (Figs 3C, 5 AI,Table 6), which is characterized by the basal opercu-lum or micropyle. Pintaud et al. (2013) showed thatsamples of this species fell in an early branchingposition in the haplotype network reconstructionbased on plastid sequence data, related to P. roebele-nii. We find this species isolated from the rest inmany aspects (habitat, seed morphology, leaf colour).

Working with outlines, Terral et al. (2012) separatedP. theophrasti, P. canariensis, P. caespitosa, P. sylves-tris and P. reclinata from a group of uncultivated (andthere undetermined) Phoenix specimens from Oman.At the same time, this group differed from severalP. dactylifera cultivar groups. Our analysis confirmsthe separation of P. reclinata, P. caespitosa and typicalP. theophrasti from Vai. However, with a wider sam-pling of P. dactylifera cultivars, our analysis shows amore complex pattern of relationships between P. dac-

tylifera and P. sylvestris, P. canariensis, P. theophrasti(from Datça, Turkey) and other taxa which were notincluded in the study of Terral et al. (2012).

TERTIARY FOSSILS

Phoenicites occidentalis (Berry, 1914: 403–406).(Cluster III, group 13) (Table 8). Type: collected byLaurence Baker in Texas, from a cut on the Interna-tional and Great Northern Railroad in southernTrinity County. The outcrop is referred to the Cata-houla formation, which in this region is of LateEocene or Early Oligocene age. The type is shown inFigure 17A. (Berry, 1914: fig. 1). The finding con-tained both large and small seeds, and a cast of entirefruit of a Phoenix-like palm (Berry, 1914, 1937). Itwas supposed to be in the Oscar M. Ball CollectionTexas Natural Science Center, The University ofTexas at Austin, or in the Smithsonian Paleontologi-cal collections (there under USNM number P38340).However, the type specimen is lost and, thus, ouranalysis is based on the figure and original descrip-tion. Weighted neighbor joining shows Phoenix dac-tylifera SIBC 11 from San José de Comondú (BajaCalifornia, Mexico) (Fig. 17B) as the closest livingsample (41% in 5000 bootstraps). However, this coin-cidence is merely accidental on palaeogeographicalgrounds, as Phoenix is clearly a recently introducedgenus in America (Rivera et al., 2010, 2013b). Total-ized dimensions present an extremely high value(Fig. 18). This is the only discovery of fossilized seeds,related to Phoenix, across America and, although itcould not be directly studied (because it is lost), thematerial must be regarded as doubtful.

Phoenix hercynica (Mai, 1976: 102–103).(Cluster III, group 14) (Table 8). Type: Tab. II, fig. 1(Holotype). Open-cast mining Neumark-Süd(Geiseltal), Stream-chute NS 22, one semi-carbonizedspecimen, complete and well preserved, leg. Chrobok195. It was not deposited in the Geiseltal Museum ofthe Martin-Luther-Universität Halle-Wittenberg,

Figure 16. Phoenix dactylifera L. A, lectotype Kaempfer (1712: table 2). B, cultivar from Ricabacica (Murcia, Spain)(PERICA_01a). Scale bars in mm. 5-mm grid. B, photograph Joaquín García.



However, the type specimen is probably at Berlin.Seed long–elliptical, 20 × 6 mm, with deep ventralfurrow (Fig. 19A, compared with P. dactylifera,Riverside-7, Fig. 19B and Riverside-5, Fig. 19C).Weighted neighbor joining shows no living samplesclosely related to this fossil. A peculiar feature of thisfossil is the extraordinarily high depth/breadth ratio(D/B = 1.33). This feature is relatively common amongfossilized materials (33% D/B > 0.95) and is rareamong living species (6% D/B > 0.95).

Fossil seeds published as Serenoa carbonaria (Mai,1976: 106) (Cluster I, group 6) (Table 8). Type:

Tab. II, fig. 10 (Holotype). Opencast mining Neumark-Süd (Geiseltal), Stream-chute NS 22, leg. Chrobok1965. The sample consists of more than 100 seedsfossilized in lignite. This and other samples fromchute NS 37, consisting of 15 specimens, leg. Chrobok1964/65, and from chute NS 38, four specimens, leg.Chrobok 1965, were not deposited in the Geiseltal-museum Zentralmagazin NaturwissenschaftlicherSammlungen der Martin-Luther-Universität (ZNS)Halle-Wittenberg and are presumably at Berlin.However, the specimens are not available. Althoughdescribed under Serenoa, the seeds, globose, ovoid or

Figure 17. Phoenicites occidentalis Berry. A, OCT_TEX (Berry, 1914). Phoenix dactylifera. B, SIBC 11. Scale bars in mm.5-mm grid. B, photograph Joaquín García.

Figure 18. Totalized dimensions of Phoenix seeds (mm3) vs. time.



ellipsoidal (Fig. 20A–D), 6–12 × 4.5–7 mm, withmicropyle dorsal, almost basal, are morphologicallyPhoenix. The Geissel fossils are c. 50 Myr old. Thisfossil falls in Cluster I, group 6, with samples ofseveral Phoenix spp. from East Asia (P. loureiroi,P. pusilla and interspecific hybrids).

Phoenix szaferi Bakowski (1967). The variablysized, peculiarly shaped, bulbous sandy bodies con-tained in coalified driftwood from the Lower Oligo-cene (Rupelian) of the Tatra Mountains in Poland,originally described as fruit bodies of a new palmspecies and then established as P. szaferi (Bakowski,1967), were reinterpreted as a maze of internalmoulds of siphonal tubes of the wood-boring bivalvemollusks of the family Teredinidae (Teredolites clava-tus) (Radwanski, 2009). The grape-like ‘fruits’ do notshow any Phoenix seed-like material.

Phoenix bohemica (Buzek, 1977: 160). (Cluster IV,group 19 whole sample, group 21 holotype)(Table 8). Type: Specimen No. TU-8 on Tab. II, fig. 8.Road cut below the garden at house no. 80, village

Tuchorice near Zatec, north-western Bohemia, CzechRepublic, freshwater, often travertine-like limestone,Tuchorice Basin, Most Formation, Burdigalian, i.e.Eggenburgian (Lower Miocene) (Buzek, 1977; Kvaceket al., 2004). Holotype deposited in the Department ofPalaeontology, National Museum Prague (Fig. 21C,D). Paratype: Specimen No. TU-2 shown in Buzek(1977). Fossil materials consist of ten fairly well-preserved seed casts or seeds replaced by crystallizedcalcite and approximately ten fragments (Buzek,1977). Seeds are oblong or ovoid, 1.2–2.0 × 0.8–1.0 cm, with a longitudinal furrow on the ventral sideand a single circular pore of germination on theopposite side, in some cases with transverse striaearound the furrow (Fig. 21A, C, D). Weighted neigh-bor joining shows as the closest living sampleFuentes 1 (Fig. 21B) (61% in 5000 bootstraps) for thewhole sample. However, weighted neighbor joiningindicates a group of P. canariensis samples as theclosest living sample to the holotype when analysedseparately (38% in 5000 bootstraps). The holotype is

Figure 19. Phoenix hercynica Mai. A, FOSS EOC_GEIS holotype (Mai, 1976: table 2, fig. 1). Phoenix dactylifera. B,Riverside-7. C, Riverside-5. Scale bars in mm. 5-mm grid. B–C, photographs Joaquín García.

Figure 20. Serenoa carbonaria Mai. FOSS_SERENCAR_1. A, holotype (Mai, 1976: table 2, fig. 10). B, specimen fromchute NS 22 (Mai, 1976: table 2, fig. 11). C, specimen from chute NS 22 (Mai, 1976: table 2, fig. 12). D, specimen fromchute NS 38 (Mai, 1976: table 2, fig. 13).



fossilized by calcium carbonate (CaCO3) (J. Kvacek,pers. comm.).

PLEISTOCENE SEEDS

At Kharga Oasis (South Egypt, West of Nile River) inLate Pleistocene deposits (16 000 BP), dated cultur-ally to Aterian (early Upper Palaeolithic) loam bedscontaining carbonized reed-stems and yielding fruitseeds of a wild date (identified by Mrs Clement Reidas P. sylvestris) have been reported (Caton & Gardner,1932) (Fig. 12A). The seeds fall in group 8(Cluster I) with several P. canariensis samples, oneP. caespitosa sample [(P. arabica) FAIRCHILD 1](Fig. 12B) and three archaeological samples.However, as the material from Kharga is carbonized,further analyses will be required with experimentalcharring of modern seeds.

Fira palaeosol has been dated to c. 37 000 BP.During fieldwork in 1975–1978, fragments of pinnatePhoenix-like foliage, casts of spines and a singleimpression of a Phoenix fruit (12 × 5.4 mm, giving11 × 5 mm as putative dimensions for the seed) iden-tified as P. theophrasti were recovered (Friedrich,Pilcher & Kussmaul, 1977; Friedrich, 1980). Thissample forms group 5 (Cluster I) with date seedfrom Queen Pu-abi’s grave (at Ur, Iraq), from Chal-colithic Teleilat Ghassul (Palestine) and from Neo-Elamite burial 693–6861 at Susa (Iran), and includes

samples of P. theophrasti collected at Vai and Prevali(Crete) and Gölköy (Turkey) and one archaeologicalNeolithic seed from Atlit Yam (Israel). Weightedneighbor joining indicates date seed from QueenPu-abi’s grave (at Ur, Iraq) as the closest sample (52%in 5000 bootstraps).

HOLOCENE ARCHAEOLOGICAL REMAINS

All archaeobotanical samples could be classified ingroups with modern seed samples. The assignment ofarchaeobotanical samples was made, mainly, to differ-ent morphotypes of P. dactylifera (Clusters III andIV). However, some samples were assigned to groupswith P. reclinata, P. caespitosa, P. atlantica, P. theo-phrasti, P. pusilla and P. canariensis. Archaeologicalseeds were not allocated to group 19 containingsamples of P. sylvestris, P. iberica and Miocene fossilP. bohemica. In general, it appears that some speciessuch as P. theophrasti had a much larger area than atpresent (reaching at least Israel and Palestine, andperhaps Iraq) and were collected and deposited incontexts that have allowed their preservation. Some-thing similar happened with P. caespitosa and P. recli-nata. By contrast, in the eastern and western ends ofthe current range of P. dactylifera, we currently findP. sylvestris and P. iberica, respectively, which do notappear in the archaeological record. This is logical aswe have not been able to study archaeological samples

Figure 21. Phoenix bohemica Buzek. MIOCENBOHEM1_10. A, specimens 1–10, including two paratype and eightholotype. Details 11–12 of specimen 2. Thirteen dorsal of specimen 8. Fourteen dorsal of specimen 9 (Buzek, 1977). Scales,10 mm. Phoenix dactylifera. B, Fuentes 1. Scale bars in mm. 5-mm grid. Phoenix bohemica. MIOCBOHEMTYPE. C,ventral view. D, dorsal view. Scale bars in mm. C–D, photographs Jiri Kvacek.



from these areas. Phoenix canariensis has two mor-photypes, of which only Group 8 (Cluster I) includesarchaeological materials from the Guanche period(Canary Islands) and others from North Africa (Egypt)and the Middle East, suggesting that this morphotypewas much more extensive than at present.

Neolithic (c. 8000–7500 BP)All studied Neolithic seeds are desiccated or water-logged. Neolithic samples from different origins (Fig. 3,Table 3) show different shapes and relationships, butthey only fall in groups 14–16 (Cluster III) of P. dac-tylifera, group 18 (Cluster IV) of P. dactylifera,P. atlantica and P. canariensis var. macrocarpa and, inone case, group 5 with P. theophrasti (Cluster I).

The coincidence of a waterlogged date seed(11.8 × 6.5 × 5.6 mm) (Fig. 11A), which was recoveredfrom Neolithic Atlit-Yam (Israel) with several modernsamples of Phoenix theophrasti from Crete (Greece)and Gölköy (Turkey) in group 5 (Cluster 1) meritsmention. Weighted neighbor joining shows twomodern samples of P. theophrasti from Vai and Gölköy(59% in 5000 bootstraps) as the morphologicallyclosest samples (Fig. 11B, C). This would confirm theidentification of the seed by Kislev et al. (2004) asP. theophrasti.

A mineralized seed recovered from Mehrgarh IB(Balochistan, Pakistan) in layers dated at c. 8000 BPis almost identical to another (Mehrgarh IIB) recov-ered in layers c. 1000 years more recent (Costantini,1985; Beech, 2003), both in group 14 (Cluster III).Two modern seed samples of P. dactylifera cultivarsalso belong to group 14 [‘Abada’ which originated inCalifornia and related to ‘Amir Hajj’ from Iraq and‘Deglet Beida’ from Algeria (Cao & Chao, 2002], as do‘Horra’ from Tunisia, 39 seeds from Bronze Age Ra’sal-Jinz (Oman), three from Bronze Age Failaka(Kuwait), and one from Middle Ages from Gao (Mali).Three seeds from Neolithic Sabiyah (Kuwait), datedc. 7530 BP, form group 16 (Cluster III), that alsoinclude the sample from Roman Masada (Israel) andseveral modern samples of P. dactylifera cultivarsfrom south-eastern Spain, West Asia and NorthAfrica. One seed from Neolithic Takarkori (Libya)falls in group 15 (Cluster III) close to a modernsample of P. dactylifera ‘Khadrawy’. Other seed fromNeolithic Takarkori (Libya) in group 18 (Cluster IV)appears to be related to modern samples of P. theo-phrasti (populations from Datça, Turkey), P. atlanticaand P. dactylifera (from south-eastern Spain, BajaCalifornia and West Asia).

Chalcolithic (c. 7400–5600 BP)Chalcolithic seed samples are brick casts (one site) orcarbonized (three sites). Chalcolithic samples fromdifferent origins (Table 3) fall in group 15

(Cluster III) of P. dactylifera, but some samples wereassigned to groups with P. caespitosa, P. theophrastiand P. canariensis (Cluster I).

Four samples (two carbonized and two brick casts)from Dalma Island (United Arab Emirates) exclu-sively form group 15 (Cluster III), with a singledesiccated seed from Bronze Age Tel Karrana (Iran)and two modern P. dactylifera samples from WestAsia. We note here the coincidence of seed imprintsand carbonized materials from Dalma in the samegroup, as it shows how different forms of conservationhave not changed the morphological relationshipsbetween them in this case.

Bronze Age (5000–3700 BP)Bronze Age seed samples are brick casts (one site),desiccated (three sites) or carbonized (four sites).Bronze Age samples from different origins (Table 3)fall in group 15 (Cluster III) of P. dactylifera, butsome samples were assigned to groups with P. recli-nata and P. theophrasti (Cluster I).

Bronze Age casts of date seeds from Ar Raqlah(Yemen) fall in group 4 (Cluster I) with severalarchaeological samples from North Africa and WestAsia and the type icon of P. reclinata. Many fragmentsof date seeds were found in Queen Pu-abi’s grave atUr (Iraq), but only a few seeds were complete enoughto measure; these fall in group 5 (Cluster I) withPleistocene, Chalcolithic and Neoelamite samples,close to modern P. theophrasti samples.

A single desiccated seed from Tell Karrana (Iran)falls in group 15 (Cluster III), with several samplesfrom Chalcolithic Dalma Island (United Arab Emir-ates), other Neolithic to Roman samples and fivemodern P. dactylifera samples from West Asia. A des-iccated date seed from Jericho (Israel) falls ingroup 4 (Cluster I), with several Bronze Agearchaeological samples (seed casts) from Yemen andmodern samples of P. reclinata. Carbonized date seedsfrom Ra’s al-Jinz (Oman) fall in group 14(Cluster III), with a carbonized seed from BronzeAge Failaka (Kuwait). These are almost identical, andthus weighted neighbor joining shows a high coinci-dence (93% of 5000 bootstraps).

Iron Age onwards (2800–800 BP)Iron Age and later seed samples are desiccated (eightsites) or carbonized (two sites from Europe). Iron Ageand later samples from different origins (Table 3) fallin groups 14–17 (Cluster III) and group 20(Cluster IV) of P. dactylifera, but some samples wereassigned to groups with P. theophrasti, P. atlantica,P. caespitosa, P. canariensis, P. reclinata and P. pusilla(Cluster I).

Desiccated dates from a Neo-Elamite burial at Susa(Iran) fall in group 5 (Cluster I) with one cast from



Pleistocene Fira (Santorini, Greece) and Bronze AgeUr (Iraq) and modern samples of P. theophrasti. Manydate seeds recovered from Raybun (Yemen) datedfrom 2800 BP onwards almost exclusively formgroup 17 (Cluster III) with one modern P. dactylif-era sample and fall in group 15 (Cluster III)(IA_RAYBU_4) with other archaeological and modernP. dactylifera samples from West Asia and group 6(Cluster I) with samples of P. pusilla, P. loureiroihybrids and Eocene Serenoa carbonaria.

Subfossil desiccated seeds from Iron Age Tayma(Saudi Arabia) fall in group 20 (Cluster IV) witharchaeological samples from Roman Karanis (Egypt)(KARANIS_9 and 6) and modern samples of P. dac-tylifera from south-eastern Spain, Baja California,West Asia and North Africa. A date seed from Par-thian Susa (Iran) falls in group 14 (Cluster III).

Desiccated date seeds from Roman Masada (Israel),which are well known for the extraordinary persis-tency of their ability to germinate (Sallon et al., 2008),fall in group 16 (Cluster III) with modern samplesof P. dactylifera from North Africa, West Asia andsouth-eastern Spain. Weighted neighbor joiningshows P. dactylifera ‘Halawy’ from Iraq as the closestmodern sample (44% in 5000 bootstraps).

Subfossil desiccated date seeds from RomanKaranis (Kom Aushin, Egypt) show different morpho-logical patterns. One sample (KARANIS_1) falls ingroup 4 (Cluster I) with several archaeologicalsamples from North Africa and West Asia, includingBronze Age casts of date seeds from Ar Raqlah(Yemen), and the type icon of P. reclinata. Anothersample (KARANIS_3) falls in group 8 (Cluster I)with Pleistocene seeds from Kharga (Egypt), otherarchaeological samples and several modern samplesof P. caespitosa (P. arabica) and P. canariensis. Othersamples (KARANIS_6 and 9) fall in group 20(Cluster IV) with archaeological desiccated seedsamples from Iron Age Tayma (Saudi Arabia) andmodern samples of P. dactylifera from south-easternSpain, Baja California, West Asia and North Africa,and KARANIS_7 and 8 fall in group 12 (Cluster III)with modern samples of P. dactylifera from south-eastern Spain and Baja California. Another sample,KARANIS_5, forms group 13 (Cluster III) with amodern sample of P. dactylifera from Baja California(Mexico) (SIBC 06) and the Eocene fossil P. hercynica.

Four date seeds recovered from a Guanche religiousoffering at Garajonay (Canary Islands, Spain)(Morales, Navarro & Rodríguez, 2011) fall in group 8(Cluster I) with other archaeological samples andseveral modern samples of P. caespitosa (P. arabica)and P. canariensis. A single seed from Middle AgesGao (Mali) falls in group 14 (Cluster III) withmodern samples of P. dactylifera from south-easternSpain, North Africa and Baja California.

ANCESTRAL TRAITS

The oldest Phoenix-related seeds (excluding the prob-lematic Phoenicites occidentalis) were recovered inCentral Europe (Phoenix hercynica, Serenoa carbon-aria). However, with the available evidence we couldnot determine if these are only isolated samples of apreviously widespread genus in the Late Cretaceousor are part of an original nucleus from which theycould diversify and colonize other territories.

We found four seed morphologies clearly defined inthe Tertiary (Table 8). However, estimating the occur-rence of evolutionary events (interpreted as specia-tion and/or evolutionary radiation) would beunrealistic according to the results and without con-sidering other sources of evidence including biology ofthe species, vegetative morphology and molecularmarkers. Morphotypes are not species and thussimply tell us that during the Tertiary a relativelyhigh morphological diversity was present.

Totalized seed dimensions show a slight tendency topresent a wider range of values, from the Miocene tothe present, but, logically, could be because modernmaterials are best represented. Phoenicites occiden-talis (Eocene of Texas, USA) has dimensions that areabnormally large (Fig. 17, Table 6).

For the purpose of representing the different pos-sible ancestral lines based on the fossils studied, wecompared the 24 groups and the outgroup (describedabove) with the four seed samples of the Tertiary andone Pleistocene sample, using the mean values of thepercentages of presence in the samples for each group(rows) and each of the 67 states analysed (columns).The resulting hierarchical tree calculated with theWard method (Fig. 22) shows clustering patterns ofmodern and archaeological samples around four dif-ferent morphologies of fossil materials.

Fossil samples fall in Cluster I (Eocene and Pleis-tocene), Cluster III (Eocene) and Cluster IV(Miocene). Archaeological samples fall in Clusters I–IV. No fossil remains (seeds) have been found relatedto P. paludosa (Cluster V).

Small Eocene (Serenoa carbonaria) and Pleistocene(Phoenix sp.) fossil seeds appear in Cluster I (Fig. 22)associated with small seeded Phoenix spp. fromSouth-East Asia and India (P. loureiroi and P. anda-manensis, groups 1, 3 and 6; P. acaulis group 2,P. pusilla, groups 2 and 6, P. rupicola group 7 andP. roebelenii group 10), Tropical Africa and the NearEast (P. caespitosa, group 3 and P. reclinata, group 4),eastern Mediterranean (P. theophrasti, group 5) andthe Canary Islands (P. canariensis, group 8). In thelight of the historical palaeogeography of the Medi-terranean Basin (Rögl, 1998), land bridges for conti-nental migrations connected Europe and Asia sincethe Aquitanian (Early Miocene), allowing the migra-



tion of Phoenix. With the collision of the Arabian andAnatolian plates in the late Burdigalian (EarlyMiocene to Mid Miocene) a Eurasian–African landbridge opened for terrestrial plant migrations, whichcould explain the above relationships. The uplift ofthe Canary Islands took place from the Mioceneonwards (Anguita & Hernán, 2000), allowing the colo-nization by plants from nearby Atlantic North Africa.

The abnormally large Eocene seed from Texas fallsin Cluster III (group 13). This morphotype appearsclearly separated from the rest of samples inFigure 22. In the same cluster, the other Eocene seedsample, from Geiseltal (P. hercynica), appears withnumerous archaeological samples and modern P. dac-tylifera cultivars (groups 14–17) (Fig. 22).

Miocene fossil seeds from Tuchorice (P. bohemica)fall in Cluster IV (Fig. 22), with numerous modernP. dactylifera cultivars from south-eastern Spain,North Africa, West Asia and Baja California(groups 12, 18–20 and 22–23), and Phoenix spp. fromthe Mediterranean (P. iberica, group 19; P. theo-phrasti from Datça in Turkey, group 18), India (P. syl-vestris, group 19) and Canary and Cabo Verde Islands(P. canariensis, group 21 and P. atlantica, groups 18

and 22). The specimen designated as the type for thespecies P. bohemica (Buzek, 1977: 160) shows closersimilarity with the type icon of P. canariensis (CanaryIslands).

The attribution of Serenoa carbonaria to Phoenix ismade on the base of the raphe and other characters ofthe fossil seeds that are present in modern and fossilPhoenix but not in modern Serenoa seeds (Table 8). Itis likely that other fossilized seeds from the Westernand Eastern Hemispheres labelled Serenoa would bemore directly related to Phoenix than to modernSerenoa spp.

To clarify the possible geographical patterns, wemap the palaeontological and archaeological sitesyielding the different samples studied: Tertiary andPleistocene (Fig. 23A) and Holocene (Fig. 23B).

APPROACH TO THE ANCESTRY OF

PHOENIX DACTYLIFERA

Although human selection practices, multiple hybridi-zation events, geographical diffusion of varieties (fol-lowing human migration routes), adaptation, etc.,may have completely blurred the evolutionary signal

Figure 22. Hierarchical tree calculated with the Ward method representing relationships between Tertiary and Pleis-tocene fossil samples and each one of the 25 groups recognized.



Figure 23. Maps of paleontological and archeological sites yielding Phoenix seeds. A, Tertiary and Pleistocene. B,Holocene.



(evolutionary radiation, ancestral traits, ancestry,etc.), which could be deduced from measurements ofthe seed in P. dactylifera, the molecular evidence sug-gests that hybridization played a limited role in theemergence of P. dactylifera, and geographical patternsof chlorotypes in the ‘Phoenix dactylifera clade’(Western and Eastern) (Pintaud et al., 2013) presentnotable coincidences with the main clusters of theanalysed seeds.

We find a surprising morphology in two of the threeEocene samples (Phoenicites occidentalis and Phoenixhercynica) that could be linked with Phoenix. Bothfall in Cluster III, and their morphology is that ofP. dactylifera. Their shape (seed elongated and large)is common and exclusive to modern date palm culti-vars. Unfortunately, type material of both fossils wasinaccessible or lost. Attribution and dating of thesesamples needs to be carefully reviewed.

Miocene fossil seeds from Tuchorice (Phoenixbohemica) show a close morphological relationship(group 19, Cluster IV) with various samples ofP. canariensis, P. iberica, P. dactylifera land races ofsouth-eastern Spain and P. sylvestris. However, thelack of archaeological materials assigned to this mor-photype suggests that it has not contributed much tothe mainstream of modern commercial P. dactyliferacultivars. It should be underlined that archaeologicalP. dactylifera samples represent almost exclusively, ingeographical terms, the Eastern chlorotype ofPintaud et al. (2013). Overall, Cluster IV showsremarkable geographical overlap with the Westernchlorotype of Pintaud et al. (2013).

The Neolithic samples from different origins (Fig. 3,Table 3) present different Phoenix dactylifera morpho-types (Table 7), but Neolithic samples fall only ingroups 14–16 (Cluster III) and group 18(Cluster IV) and Chalcolithic and Bronze Agesamples fall in only group 15 (Cluster III) of P. dac-tylifera. Iron Age and later samples fall ingroups 14–17 (Cluster III) and group 20(Cluster IV) of P. dactylifera. Apparently, the greatdiversity of P. dactylifera morphotypes during theNeolithic was followed, during the Chalcolithic andthe Bronze Age, by a remarkable constriction (bottle-neck) in terms of morphological variability, whichslowly recovered from the Iron Age onwards. Thisbottleneck could be related to the genetic bottleneckoccurring between the 8th and 5th millennium BP inthe domestication model proposed for the date palmby Pintaud et al. (2013).

With the currently available evidence, we cannotexclude the proposal made by Terral et al. (2012)concerning a group ancestral to P. dactylifera in thePersian Gulf, related to the Eastern chlorotype ofPintaud et al. (2013). Furthermore, in parallelanother group ancestral to P. dactylifera may exist in

the Western Mediterranean, including P. ibericarelated with the Western chlorotype. However, thedirect wild ancestor of the date palm is still unknownand this issue remains unsolved, although we canassume that the direct wild ancestor of the date palmpossessed small and elliptic seeds.

GEOGRAPHICAL GROUPS

Major geographical patternsWhen analysing the geographical origins of samplescoinciding in clusters and groups, several patterns ofrelationships became evident (Fig. 24). To clarify thesegeographical patterns we summarized the distributionareas of the different species studied (Fig. 25). A groupbrings together south-eastern Spain, North Africa andBaja California (Fig. 24). This group comprises P. dac-tylifera local cultivars and suggests the original prov-enances of the palms introduced in America wereSpain and North Africa (as documented by Riveraet al., 2013b). Another group clearly links archaeologi-cal samples and West Asia, based on the association ofarchaeological materials with modern samples ofP. dactylifera from Iraq, Iran and the Arabian Penin-sula. However, as pointed out by Terral et al. (2012),morphological diversity appears to be only slightlystructured according to the geographical origin ofP. dactylifera cultivars. The pairwise relationship, con-cerning seed morphology, of P. theophrasti–P. reclinatais reflected in the association of Eastern Mediterra-nean to Tropical Africa. India, East Asia and Macaro-nesia appear, each one, relatively isolated.

Phoenix dactylifera in Baja California (Mexico)At present, the major extant palm groves of Spanishorigin in the Americas are situated in Baja California.Documentary evidence about the introduction of datepalms during the first century of the missions (i.e. the18th century) in Baja California is contradictory.However, date palm cultivation was well establishedin several mission areas by the 1750s. (Rivera et al.,2013b). Preliminary molecular results show littlegenetic diversity and suggest the introductionoccurred once in one mission (presumably Loreto) andfrom there to the rest (Rivera et al., 2010).

All Baja California seed samples fall in groups 12,13 and 17 (Cluster III) and groups 18, 19 and 20(Cluster IV), which include P. dactylifera cultivarsand related species. Seed morphology does not show ageographical pattern in Baja California. Samples fallin six of the 12 groups recognized for Clusters III andIV. A few samples coincide in one group (Fig. 3), e.g.group 12 (Cluster III): SIBC 3 (San Ignacio),SIBC 15 (Loreto), SIBC 19 and 20 (La Purísima),SIBC 11, 12 and 22 (San José de Comondú). Thus,morphological diversity is relatively high, particularly



in San Ignacio. Concerning coincidences with speciesand cultivars from abroad it is to be noted that therelative morphological similarity between SIBC 11(San José de Comondú) and Phoenicites occidentalisfrom Eocene of Texas, the weighted neighbor joiningtree shows 52% coincidence with 5000 bootstraps.However, a factorial analysis (PCoA) shows this coin-cidence is superficial. SIBC 20 (La Purisima) closelyresembles Orisa 4 (Orihuela, Spain), and SIBC 23(San Ignacio) coincides with Isla Plana 1 (Cartagena,Spain). In relation to archaeobotanical materials,SIBC 6 (San Ignacio) and SIBC 11 (San José deComondú) show coincidences with Karanis 5 (Romanperiod, Egypt). Overall, samples show high coincidencewith samples from Elche and Abanilla–Fortuna(south-eastern Spain). Seeds from Mulegé (SIBC 16,17) show coincidences with samples from the NearEast.

CONCLUSIONS

Seed morphology including shape or outline, total-ized dimensions, superficial processes, shape ofraphe, apex and base and position of micropyle, istaxonomically useful. Twenty-four morphotypes weredifferentiated into three major clusters. Of these, 12

morphotypes represent the variability of P. dactylif-era. Regarding the existence of continuity in time,nine morphotypes include only modern seedsamples, two morphotypes include modern and fossilsamples, nine morphotypes include modern andarchaeological samples and four morphotypesinclude both modern and archaeological samples andfossils.

Eight species have characteristic seeds and areclearly assigned to morphotypes [P. acaulis, P. canar-iensis s.s., P. paludosa, P. reclinata, P. roebelenii,P. rupicola, P. sylvestris and P. theophrasti (excludingpopulations of Datça, Turkey)], but the others cannotbe clearly separated on the sole basis of the morphol-ogy of seeds.

Geographical patterns are detected for main groupsand clusters in the genus Phoenix. However, morpho-logical diversity and geographical origin of P. dactyl-ifera cultivars are not clearly related. A majorgeographical western/eastern pattern related withpreviously described chlorotypes is detected in P. dac-tylifera.

With the currently available evidence, we cannotexclude a group ancestral to P. dactylifera in thePersian Gulf, related to the Eastern chlorotype. Fur-thermore, in parallel, another group ancestral to

Figure 24. Hierarchical tree calculated with the Ward method representing relationships between large geographicalzones based in the coincidence of samples of known origin in each one of the 25 groups recognized.



A B

C D

E F

G H

Figure 25. Distribution maps of Phoenix species. A, 1. P. canariensis; 2. P. atlantica; 3. P. iberica; 4. P. theophrasti. B,1. P. reclinata; 2. P. sylvestris. C, P. dactylifera. D, P. caespitosa. E, P. loureiroi, 1. ‘Pedunculata’; 2. ‘Humilis’; 3.‘Loureiroi’; 4. ‘Hanceana’. F, P. pusilla; 1. ‘Zeylanica’; 2. ‘Farinifera’; 3. P. acaulis. G, 1. P. roebelenii; 2. P. andamanensis.H, 1. P. paludosa. 2. P. rupicola.



P. dactylifera may exist in the Western Mediterra-nean, including P. iberica, related to the Westernchlorotype.

Apparently, the great diversity of date seeds mor-phology during the Neolithic was followed, during theChalcolithic and the Bronze Age, by a remarkableconstriction (bottleneck) in terms of morphologicalvariability of dates of P. dactylifera, which slowlyrecovered from the Iron Age onwards.

More detailed studies are needed of a greaternumber of clearly identified modern samples (espe-cially with increased representation of diversity inSouth-East Asia) and archaeological samples (clearlyradiocarbon dated) to deepen the knowledge of mor-phological variation patterns in time and space. Forthis purpose, it is essential to increase the presence ofspecimens in herbaria, with well-preserved samplesof dried seeds (not just fruit), in suitable condition tobe studied (at least 30 seeds). Institutions thatmanage collections of modern plant material (her-baria and repositories) and archaeological and fossil(museums) should ensure that such materials arelocalizable and available to researchers. It would beespecially useful to put online quality images of allmaterials, especially nomenclatural types, as isalready underway in some large herbaria.

ACKNOWLEDGEMENTS

This research received, for the Spanish part, supportfrom the INIA projects RF2007-00010-C03 andRF2010-00006-C02 (European Regional DevelopmentFund 2007–2013). For assistance in finding type andarchaeological materials, we thank Dr Jiri Kvacek(Head of the Department of Palaeontology, NationalMuseum Prague), Dr Frank D. Steinheimer (LeitungZentralmagazin Naturwissenschaftlicher Sammlun-gen, Martin-Luther-Universität Halle-Wittenberg),Dr Mark Nesbitt (Royal Botanic Gardens, Kew), DrMarina Clauser (Orto Botanico, Universitá degliStudi di Firenze), Dr Jacob Morales (Universidad deLas Palmas), Dr Anat Hartmann-Shenkman and Pro-fessor Mordechai Kislev (Bar Ilan University) and DrMaxine Kleindienst (Toronto University).

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SUPPORTING INFORMATION

Additional Supporting Information may be found in the online version of this article at the publisher’s web-site:

Appendix S1. List of modern Phoenix seed samples analysed from Herbaria, Germplasm repositories andCarpological Collections.Appendix S2. Crude matrix.Appendix S3. The matrix of correlation between variables.



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carpological analysis of phoenix (arecaceae...

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