eriogonum ursinum var. erubescens new trinity county sites

8/3/2019 Eriogonum ursinum var. erubescens New Trinity County Sites

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23 Sept 2011 ‐ Dean W. Taylor, Ph.D.

Eriogonum ursinum assessment: Trinity County sites

Summary: newly documented Trinity County and Shasta County Eriogonum ursinum sites are determined as Eriogonum ursinum

var. erubescens, a CNPS RARE taxon.

Eriogonum ursinum is endemic to California: E. ursinum var. ursinum is known from >100 sites in the Cascade Ranges and northern

Sierra Nevada

(based

on

CCH

herbarium

specimen

database).

By

contrast,

E. ursinum

var. erubescens

is

considered

a narrow

endemic (CNPS List 1B.3) reported in literature to be limited to Gunsight Peak vicinity, Siskiyou county, with an outlier on Trinity

Mountain, Shasta County (Reveal & Knorr 2004). Recently, several new occurrences of E. ursinum were located in Trinity and Shasta

Counties which prompted review of the taxonomic circumscription of the these entities. This review provides assessment of the

taxonomic features of Trinity County and western Shasta County occurrences which show they exhibit characteristics consistent with

the rare E. u. var. erubescens, and that the original circumscription of E. ursinum var. erubescens (Reveal & Knorr 2004) incorrectly

characterized that taxon as having umbellate inflorescences.

Circumscription (Reveal & Knorr 2004)

The protolog of E. ursinum var. erubescens states (quoting the abstract): “...differs from var. ursinum...in having an umbellate (not biumbellate) inflorescence, longer peduncles (5‐25 vs. 2‐5 mm) in fruit,

involucres (4.5‐8 vs. 3.5‐4.5 mm), mature flowers (5‐9 vs. 5‐6 mm) and achenes (5.5‐8 mm vs. 3‐5 mm).”

and; the Latin diagnosis (Reveal & Knorr 2004) circumscribes var. erubescens as:

“a var.

ursino

inflorescentiis

umbellatis (nee

biumbellatis)

divisis

differt.”

Reveal and Knorr (2004, p. 164) also state:

“As a result the inflorescence in Eriogonum ursinum var. erubescens is a single umbel whereas it is typically branched twice (or

biumbellate) in var. ursinum...

Reveal (2005) separates the infrataxa of Eriogonum ursinum on the following basis, and does not key the two taxa based on

inflorescence architecture:

Flowers 5–9 mm, perianth cream (rarely yellow); achenes (5‐)5.5–8 mm...............………………………………......... var. erubescens

Flowers 4–6 mm, perianth pale yellow or rarely yellow; achenes 3–3.5 mm..…………………....……………………………... var. ursinum

Reveal (2011 in press) separates the infrataxa of Eriogonum ursinum on the following basis, also without reference to inflorescence

architecture:

Fls 5–9 mm, cream (or yellow); fr (5)5.5–8 mm; KR ........................................................................................... var. erubescens

Fls 4–6 mm, pale yellow (or yellow); fr 3–3.5 mm; s CaR, n SN ............................................................................... var. ursinum

There is no specific inconsistency in the two Reveal keys, there are characters mentioned specifically in the protolog of var.

erubescens such as: Reveal (2005, p. 358) characterizes E. u. var. ursinum” “perianth...becoming suffused with blush of pinkish red

to maroon.:” while var. ursinum “...not suffused with blush of color.” Table 1 encapsulates the putative differences as described

above.

Table 1. Character states for a qualitative character, and measurements for quantitative characters given for E. ursinum var. ursinum and E.u.

var. erubescens in Reveal & Knorr (2004).

In the summer of 2011, plants of Eriogonum ursinum located from Trinity and Shasta Counties were initially thought not to be E. ursinum var. erubescens based on the lack of a simply umbellate inflorescence. The purpose of this note is to indicate that both E. ursinum var. ursinum and E. ursinum var. erubescens have a compound‐umbellate inflorescence structure (contrary to Reveal &

Knorr 2004, later corrected in Reveal 2005 it should be noted), and to highlight the circumscription of the rare E. ursinum var.

erubsecens.

Taxon Inflorescence

Branching

Peduncle

Length (mm)

Involucre length

(mm)

Flower length

(mm) Flowers

Achene

length

(mm)

E. ursinum

var.

ursinum

bi‐

umbellate

2

– 5

mm 3.5

– 4.5

mm 5

– 6

mm non

blushing 3

– 5

mmE. urisnum var. erubescens umbellate 5 – 25 mm 4.5 – 8 mm 5 – 9 mm blushing 5.5 – 8 mm



The tabulation below provides measurements/assessment of Trinity County occurrences: achene length was not determined for

most sites as seeds were not yet ripe at the time of measurement.

Table 2. Measured sizes of 10 involucres, peduncles or achenes and 30 flowers (mm).

Site Taxon

Peduncle

Length (mm)

Involucre

length

(mean ± S.D.)

Flower length

(mean ± S.D.)

Flower color

aging

Achene

length

(mean ± S.D.)

Trinity Mountain

(paratype)

erubescens 5.48

± 1.8

range 3.8 – 7.5

6.1 ± 0.4

6.15

± 0.57

range 5.4 – 7.2

embarrassed

Not ripe

Mikes Peak erubescens 9.9 ± 2.4

range 6.3 – 12.8

5.8 ± 0.5

5.49 ± 0.67

range 3.6 – 6.5

blushing Not ripe

N Fork Salt Creek erubescens 7.9 ± 0.5

range 6.8 – 8.9

6.1 ± 0.3

6.45 ± 0.41

range 5.6 – 7.7

blushing 4.7 ± 0.6

Onion Creek erubescens 9.2 ± 2.4

range 6.2 – 13.6

5.1 ± 0.3

4.01 ± 0.53

range 3.1 – 5.1

blushing Not ripe

W of Burks Peak erubescens 10.5 ± 2.5

range 6.1 – 15.0

5.8 ± 0.8

6.44 ± 0.44

range 4.9 – 7.2

blushing 4.0 ± 0.4

Near Trinity Center (#21135) erubescens 6.8 ± 1.5

range 4.5 – 8.8

5.9 ± 0.3

5.25 ± 0.62

range 3.7 – 6.2

blushing Not ripe

Yuba River (type locality) ursinum 4.13 ± 0.7

range 3.0 – 5.5

4.06 ± 0.44

4.46 ± 0.17

range 2.9 – 5.5

forward 3.3 ± 0.3

Definitions: embarrassed

–

blushing

prior

to

or

at

anthesis;

forward,

blushing

only

rarely

and

then

at

great

age

General Features of these plants

The two taxa of Eriogonum ursinum are distinct: no specimens have been seen which suggest any significant degree of intermediacy

Generally, var. erubescens is about 50% larger in all aspects of the inflorescence and flowers compared to var. ursinum (see Fig. 3

below). To be sure, the size difference is such, given the overall prevailing viewpoint with respect to classification of Eriogonum, the

two might well be considered separate species. As noted by Reveal & Knorr (2004), the peduncles, involucre and flowers are larger

in var. erubescens than var. ursinum. Another significant difference is the overall size of the inflorescence itself, which is much

larger in var. erubescens by virtue of the generally longer 1st order and 2

nd order segments of the inflorescence (see attached

specimen scans). One aspect of the overall size difference between the two infrataxa of Eriogonum ursinum is that var. erubescens

has much longer scapes than does var. ursinum, also by about a factor of 50%. The scapes of var. erubescens can be up to nearly 5

dm tall, while those of var. ursinum are usually not over 3 dm tall (again, see attached specimen scans). This feature was not used in

the key.

Blushing

E. ursinum var. erubescens flowers quickly ‘blush’ at and just after anthesis such that most inflorescences appear reddish (see Fig. 3

& 5), while E. ursinum var. ursinum flowers are more ‘forward’ in the sense that they some do blush eventually, but not to the

rapidity and degree in var. erubescens (see Fig 3 & 7). Some of the Trinity County occurrences of Eriogonum ursinum var. erubescens

blush after anthesis, while one occurrence (Mikes Peak) I will characterize as embarrassed as plants at this site ‘blush’ before

anthesis.

Peduncle Length

In Eriogonum, a peduncle is by definition that inflorescence

structure subtending an involucre. In Eriogonum ursinum,

variation in peduncle length is evident, the variation resultant

from two

factors:

1)

var.

erubescens

has

intrinsically

longer

peduncles, and 2) variability suggestive of differential gene

expression during inflorescence development. Fig. 1 (left)

shows an inflorescence of E. ursinum var. erubescens with

differential expression of inflorescence branching genes.

Typically, a peduncle is a third‐order structure, that is, they

are subtended by two‐orders of branching. In this

inflorescence, the central (terminal upon the meristem)

inflorescence segment is unbranched (that is, compared to

neighbors, lacks two divisions) and therefore has a ‘peduncle’

about 20 mm long. Other segments of the inflorescence lack

one‐branching order, and thus have peduncles that can be



about 12 mm long. Peduncle length does differ between E. u. var. ursinum and E. u. var. erubescens as in the Reveal (2005) key: the

salient difference should be determined only from peduncles that are third‐order.

Distribution Figure 2. Eriogonum ursinum distribution: black dots are var. ursinum; red dots are var. erubescens (including new sites reported herein). The CCH specimen distribution of Eriogonum ursinum is

mapped here: most of the specimens of var. ursinum

conform to the stated range (Reveal & Knorr 2004, Reveal

2011 in press), with the exception of outliers in Del Norte

County (open circles on the map, SBBG1653 and one

Tulare County specimen, SBBG1654). On this basis, the

distribution of E. ursinum var. erubescens is indeed north

and west of that of var. ursinum. The taxonomic

assignment of the outliers is suspect .

In Shasta County, the gap between the known sites for var

ursinum and

var.

erubescens

is

in

the

canyons

of

the

McCloud and Pit Rivers; the closest western approach of

var. ursinum is on Grizzly Peak, Shasta County (JEPS88652)

about 20 air miles from the easternmost known site for

var. erubescens. Exploration of high rocky ridges in this

region should seek to document presence or absence of

either taxon locally. The reported southerly station for

var. ursinum (Bully Choop Mountain) is apparently not

vouchered.

The two population centers for E. ursinum var. erubescens are separated by about 50 air miles. No indication has been seen in the

available specimens that the two population centers for var. erubescens differ in any way.

Endangerment Status: Including the sites reported herein, Eriogonum ursinum var. erubescens is known from 13 occurrences.

Conclusion: the uncertainty over the circumscription of Eriogonum ursinum var. erubescens based on a literal reading of Reveal &

Knorr (2004) is due to the fact that the protolog mis‐states the degree of inflorescence branching. Contrary to the Latin description,

E. ursinum var. erubescens has a biumbellate inflorescence.

The keys provided by Reveal (2005, 2011 in press) are correct.

Clarification of the problems associated with the circumscription of Eriogonum ursinum var. erubescens was needed, being that it is

a CNPS rare plant. It was not treated in Rare Plants of Northern California.

References:

Reveal, J.R. and J.K,. Knorr 2004. A new variety of Eriogonum ursinum (Polygonaceae: Eriogonidae). Phytologia 86(3):160‐168

Reveal, J.R. 2005. Eriogonum, in Flora North America, Vol. 7. Oxford Univ. Press

Reveal J.R. 2011? Eriogonum, in Jepson Manual revision (in press)



Newly Documented Stations vouchered by specimens

TRINITY COUNTY: 3.5 air miles NNW of Trinity Center, ridge dividing Hatchet Creek from Buckeye Creek watersheds; T37N R8W

S25; Carville 7½’ USGS quadrangle; alt. 3950 ft.; rocky metamorphic north facing slope characterized by Polystichum imbricans,

brushy Quercus chrysolepis & Toxicodendron, and Pseudotsuga menziesii open canopy. Latitude/Longitude (GPS, NAD27) 41.03258/‐

122.7245; Thursday, August 04, 2011; Dean Wm. Taylor #21143 with Tom Engstrom, Jason Poburko (JEPS). [“Hinkey THP”]

TRINITY COUNTY:

Mikes

Peak

(ca

5 air

miles

S of

Lewiston);

T32N

R8E

Section

18;

Lewiston

7½’

USGS

quadrangle;

alt.

4370

ft.;

sparse canopy serpentine woodland with stunted trees of Pinus ponderosa, Calocedrus decurrens, and Festuca idahoensis prominent in otherwise sparse herbaceous vegetation; steep rocky easterly facing slope; Latitude/Longitude (GPS, NAD27)

40.62908/‐122.8064; Thursday, August 04, 2011; Dean Wm. Taylor #21144 (JEPS); Tuesday, May 15, 2007, #20454 (JEPS).

SHASTA COUNTY: 0.9 air mile west of High Mountain and 6.65 air miles east of Highway 5 and Pollard Flat, along a draw draining to

North Fork North Salk Creek; T36N R04W S11; Hanland Peak 7½' USGS quadrangle; alt. 3300 ft.; steep open rocky slope, northwest

aspect; Latitude/Longitude (GPS, NAD27) 40.99185/‐122.28964; Thursday, July 15, 2011; Tom Harrington s.n. (SPI herbarium)

["Mission Impossible II THP"]

SHASTA COUNTY: Southeastern slope of peak between Onion Creek and Stacey Creek drainages, ~9.37 air miles west of Lakehead.

T35N R06W S09 SW 1/4 of the NW 1/4. Damnation Peak 7½' USGS quadrangle; alt. 4432 ft.; Rocky opening in forest with 0% canopy

50% slope, Toxicodendron diversilobum, Cercis occidentalis, Erigeron inornatus var. inornatus, Quercus kelloggii, Calystegia occidentalis, Achnatherum sp., Viola purpurea, Calocedrus decurrens, Pseudotsuga menziesii, Pinus ponderosa. Latitude/Longitude

(GPS, NAD27) 40.90612/‐122.56047; 19'accuracy; Thursday, July 14, 2011; Jessica O'Brien s.n. (SPI herbarium). ["Milkbone THP"]

SHASTA COUNTY: 0.75 air mile W of Bucks Peak (ca 2.2 air miles ENE of Lakehead); T35N R04W S05; Hanland Peak 7½' USGS

quadrangle; alt. 2625 ft.; rocky cliff faces alongside and above dirt logging road, steep western facing slopes, fairly barren with

scattered clusters extending up slope growing with Quercus chrysolepis and Lomatium sp., open canopy; Latitude/Longitude (GPS,

NAD27) 40.91385/‐122.33897; Thursday, June 30, 2011; Jessica O'Brien and Stephanie Puentes s.n. (SPI herbarium) ["Long Tom

THP"]



Photographs

Figure 3 ‐ Comparison of Eriogonum ursinum infrataxa Upper Pair: Eriogonum ursinum var. ursinum northern Sierrra

Nevada (Sierra County); Lower, Eriogonum ursinum var. erubescens (Trinity County and Shasta County).



Photographs (continued)

Figure 4 ‐ Eriogonum ursinum var. erubescens, Mikes Peak (#21144)

Figure 5 ‐Mikes Peak ERURE site (serpentine, sparsely vegetated, characterized by sparse Festuca idahoensis)



Figure 6 ‐ 3.5 air miles NNW Trinity Center site for ERURE (#21134), rocky outcrop characterized by the fern Polystichum imbricans

Figure 7 ‐ Eriogonum ursinum var. ursinum (Middle Yuba River, Sierra Nevada, topotype, #21154) showing both 'forward' (unblushed) and

blushed inflorescences on the same clone



Figure 8 ‐ Eriogonum ursinum var. ursinum Middle Yuba River (Sierra Nevada, as above)

eriogonum ursinum var. erubescens new trinity county sites

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