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Brittonia, 32(3), 1980, pp. 368-371.9 1980, by the New Y ork Botanical Ga rden, Bron x, NY 10458S P I R A N T H E S D E N D R O N E U R A ( O R C H I D A C E A E ) , A N E W

S P E C I E S F R O M C H I H U A H U AC . J . S H E V I A K A N D R . A . B Y E , JR .

Sheviak , C . J . (B io log ical Survey , N ew Y ork Sta te Museum , The Sta te Ed u-cat ion Depar tm ent , A lbany , NY 12230) and R . A . Bye , Jr . (Depar tme nt o f En-v i ronmenta l , Popula t ion and O rganismic B io logy and the Unive rs i ty o f ColoradoMuseum, Univers i ty o f Colorado , Boulder , CO 80309) . Spiranthes dendroneura(Orc hidac eae), a new spec ies from Chihuahua. Bri t tonia 32: 368-371. 19 80.--Spi ran thes dend roneura , a new species from the p ine-oa k fores t s o f nor thw es ternM ex i co , r e s em b l es S. parasitica an d S. valerioi in the slender leafless floweringhabi t , the so l i t ary , tuberous ly th ickened ro o t , and the ca l l i a t the base of the l ip ,bu t d i f fers by the d i s t inc t ive shape of the l ip which l acks a red c en t ra l th icken ing .

C o n t i n u i n g f lo r i s t i c w o r k i n t h e S i e r r a M a d r e O c c i d e n t a l o f C h i h u a h u a , M e x i c o ,b y t h e s e c o n d a u t h o r h a s p e r i o d i c a l l y y i e l d e d p o o r l y k n o w n t a x a ( B y e & S o l t i s ,1 97 9) o r u n d e s c r i b e d s p e c i e s ( B y e & C o n s t a n c e , 1 97 9; C o n s t a n c e & B y e , 1 97 6) .O n e s u c h n e w p l a n t , a d i m i n u t i v e S p i r a n t h e s , i s t r e a t e d h e r e . T h e p l a n t s w e r ef i rs t c o l l e c t e d i n 1 97 3 f r o m a d r y o p e n f i e l d i n p i n e - o a k f o r e s t s o u t h o f t h e B a r -r a n c a d e l C o b r e . T h e s p e c i m e n s f r o m t h is c o l l e c t i o n w e r e i n c l u d e d w i t h a s e t o fo t h e r o r c h i d s g i v e n t o t h e f i r s t a u t h o r f o r d e t e r m i n a t i o n a n d w e r e r e c o g n i z e d a su n d e s c r i b e d . W i t h f a m i l i a r i t y g a i n e d f r o m t h i s a n d s u b s e q u e n t c o l l e c t i o n s , i t h a sb e c o m e a p p a r e n t t h a t t h e p l a n t s w a r r a n t d e s c r i p t i o n a t th e s p e c i f i c l e v e l .Spi r a nt he s de ndr o ne ur a S h e v i a k & B y e , s p . n o v . ( F i g . 1 )

He rba perennis erec ta 10-20 cm al t a , g rac i l is s implex g labra , pa l l ide v inoso-fer rug inea , rad ic ibusso l i t ar i is tuberoso- incra ssa t i s 20-27 mm longis e t 4 -7 mm diam. d escende nt ibus , fo l ii s rad ica l ibusfugacibus hys teran th i s , cau l ibus g raci l ibus usque ad 1 mm diam. b rac te i s (5 ) 7 -8 vag inan t ibus scar ios i sins t ruct i s , sp ic i s l ax i s 25-50 mm longis , 6 -8 mm diam . , b rac te i s f lor iferi s scar ios i s acuminat i s 5 -7 mmlongis . Flores (3) 4 -8 (9) , in ter se d i s tan tes (ad 9 ram) secun di vel in sp i ram laxam con tor t i , ovaf ioerec to 2-4 mm longo , 1 .5 -2 .0 mm diam . , per ian th io hor izon ta l i ve l l ev i t er ascen dent i , sepa l i s e tpeta l i s pa l l ide v inoso-fer rug inei s , nerv i s v i f ido- lu te is fer rug inescen t ibus l abel lo a lbo , in cen t ro v i r id i -lu tescen t i nerv i s v i r id io- lu te i s ins t ructo , fer rug ina scen t ibus , sepal i s l a tera l ibus 4 m m longis , 1 mmlat i s , lanceo la t i s acu t i s un inerv i i s , sepalo dorsa l i 5 mm longo 1 .5 mm la to l anceo la to acu to un inerv i ,pe ta l i s 4 mm longis 1 mm la t i s l anceo la t i s subacut i s un inerv i i s , l abel lo 4 mm longo 2 .5 mm la tomembranaceo vel in cen t ro l aminae succu len to ovato ob tuso prope bas in d i l a ta to , nerv i s l a tera l ibuspaten t i - ram os i s , tubercu l i s basal ibus humi libus ro tundat i s o bscur i s , ros te l l i ros t ro b rev i , sem in ibusel l ipso idei s ve l fus ifo rmibus sae pe to r t i l ibus , monoem bryonat i s . Fo l ia matura ignota .S l e n d e r e r e c t p e r e n n i a l h e r b , w h o l l y g l a b r o u s , 1 0 -2 0 c m t a ll . R o o t s o l i t a r y ,t u b e r o u s l y t h i c k e n e d , 2 0 - 2 7 m m l o n g , 4 - 7 m m t h i c k , d e s c e n d i n g . L e a v e s a p -p e a r i n g a f t e r a n t h e s i s , f u g a c e o u s , w h o l l y b a s a l . S t e m a n d i n f lo r e s c en c e p a l e v i n a -c e o u s - r u s t . S t e r n s l e n d e r , t o 1 m m t h i c k , b e a r i n g ( 5 ) 7 - 8 l o o s e l y s h e a t h i n g s c a r -i o u s b r a c t s 8 - 1 8 m m l o n g . S p i k e l a x , 2 5 - 5 0 m m l o n g , 6 - 8 m m i n d i a m e t e r . F l o r a lb r a c t s s c a r i o u s , o v a t e , a c u m i n a t e , 5 - 7 m m l o n g . F l o w e r s ( 3) 4 - 8 ( 9 ), s p a c e d t o9 m m a p a r t , i n a l o o s e s p i r a l t o n e a r l y s e c u n d ; o v a r y e r e c t , 2 - 4 m m l o n g , 1 . 5 - 2m m i n d i a m e t e r ; p e r i a n t h h o r i z o n t a l t o s l i g h t ly a s c e n d i n g ; s e p a l s a n d p e t a l s p a l ev i n a c e o u s - r u s t , s t r i p e d w i th v i n a c e o u s - r u s t ; l ip w h i t e , b e c o m i n g g r e e n - y e l l o wc e n t r a l l y , v e i n e d w i t h g r e e n - y e l l o w , t h e v e i n s b e c o m i n g r u s t . L a t e r a l s e p a ls 4m m l o n g , 1 m m w i d e , l a n c e o l a t e , a c u t e , 1 - n e r v e d ; d o r s a l s e p a l 5 m m l o n g , 1 .5m m w i d e , l a n c e o l a t e , a c u t e , 1 - n e r v e d . P e t a l s 4 m m l o n g , 1 m m w i d e , l a n c e o l a t e ,a c u t i s h , b u t w i t h th e v e r y t i p b l u n t , 1 - n e r v e d . L i p 4 m m l o n g , 2 .5 m m w i d e ,m e m b r a n a c e o u s t o f l e s h y c e n t r a l l y , o v a t e , o b t u s e , s o m e w h a t d i l a te d b a s a l l y , w i t hd e n d r i t i c v e n a t i o n ; b a s a l c a l l i l o w , r o u n d e d , o b s c u r e . R o s t e l l u m w i t h a s h o r t

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1980] S H E V I A K & B Y E : S P I R A N T H E S 3 6 9

FIG. 1. Spiranthes dendroneura She viak & Bye . A . L ip , x 16. B . See d , x 175 . C . P lan t , x 1 .4 .

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370 BRITTONIA [VOL. 32beak. S e e d s ellipsoidal to fusiform, often spiralled or contorted, monoembryonic.M a t u r e l e a v e s unknown.TYPE: MEXICO. CHIHUAHUA: Municipio de Urique, Saw~irare, near Napuchiand NE of Samachique (27~ 107~ S of Barranca del Cobre, at 2400 melev., 2 Jun 1973, R. A . By e , J r . 3944 (HOLOTYPE: NYS; ISOTYPE: COLO).Other specimens: MEXICO. CHIHUAHUA: Type locality, 3 Jun 1978, R. A.By e , J r . 8565 (COLO).S p i r a n t h e s d e n d r o n e u r a appears to be close ly allied to S . p a r a s i t i c a A. Richard& Galeotti and S. va ler io i Ames & Schweinfurth [S. p a r a s i t i c a R. & G. var.v a le r io i ( A . & S.) L. Williams]. In general aspect it immediately suggests thesespecies, being small and slender, leafless at anthesis, and of a curious pale pur-plish tan color throughout. The obscure calli at the base of the lip are comparablein the three, and at once separate them collectively from the superficially similarS . I lav e ana Lindley var. v io lac e a (A. Richard & Galeotti) Ames & Correll. Thesolitary, tuberously thickened root is particularly suggestive of S . p a r a s i t i c a .From this species S . d e n d r o n e u r a is immediately separable by the lack of the redcentral thickening of the lip which is characteristic of S . p a r a s i t i c a . From bothS . p a r a s i t i c a and S. va ler io i , which lacks the red coloration, S . d e n d r o n e u r a isfurther distinct in the shape of the lip, which is broadly ovate and, in comparisonwith its length, much broader than those of the other two species. It furthermorelacks the supramedian constriction and suborbicular apical dilation of S . p a r a s -i t ica and S. va ler io i . In some material of S . d e n d r o n e u r a , however, it is possibleto see a slight constriction separating the broadly expanded basal portion of thelip from the short-oblong apical segment, further suggesting a probable relation-ship among the three species. S p i r a n t h e s d e n d r o n e u r a also differs from its rel-atives in the slightly smaller flowers and from the pubescent S . p a r a s i t i c a inbeing wholly glabrous.The most distinctive feature of S . d e n d r o n e u r a is the pattern of venation ofthe lip. Unlike its relatives and nearly all other small-flowered S p i r a n t h e s , inwhich the nervature consists of a few parallel strands, S . d e n d r o n e u r a has adistinct dendritic proliferation of the more laterally positioned veins. The branch-es spread into the dilated portions of the lip and may reflect an elaboration of thevascular system coincident with a broadening of the lip from an ancestral formsimilar to that found in the species' closest relatives. The nerves are clearlyevident, at first outlined in greenish yellow on the white lip, and later becomingbrown as the center of the lip darkens to a deep yellow. In pressed material thecolor patterns generally persist, although a brownish suffusion may develop cen-trally and obscure the nerves in this region. This nervature is so distinctive thatit has contributed the specific epithet.Leaf form of the species is unknown. In the field the plants have been collectedonly in bloom, and in cultivation they have produced one or few oblong, sessileleaves about 1 cm long. Whether these leaves are characteristic of the species orthe products of poor culture is not yet known.S p i r a n t h e s d e n d r o n e u r a occurs in sunny openings in dry pine-oak forests ofsouthwestern Chihuahua. This region experiences a cool, dry winter, after whichthe leafless spikes of this orchid appear in late spring or early summer . The leavesappear later in the summer after seed dispersal and are relatively short-lived,senescing in late summer or autumn. The single tuberous root supports the inflo-rescence and later the developing leaves. During the summer a new root is pro-duced, generally growing downward at an oblique angle, and the root of thepreceding year withers. In cultivation, exclusion of pollinators from a single spikeprecluded seed set, indicating that this plant is not apomictic.

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1980] S H E V I A K & B Y E : S P I R A N T H E S 3 7 1A c k n o w l e d g m e n t s

The authors wish to express their gratitude to Dr. W. A. Weber for constructivecomments and for improving the Latin description; to Dr. L. A. Garay for theuse of the facilities of the Oakes Ames Orchid Herbarium and for his criticismand support of Sheviak's work on Spiranthes; to Rev. L. Verplancken of Creel,Chihuahua, for several years of encouragement and support of Bye' s field work;and to Deborah Morrison for drawing the figure of the plant. The first author'swork on Spiranthes has been supported by the American Orchid Society Fundfor Education and Research; Botanical Museum and Department of Biology,Harvard University; and Biological Survey, New York State Museum. The sec-ond author gratefully acknowledges financial support from National ScienceFoundation Grant GB-35047; National Geographic Soc iety; Botanical Museumand the Department of Biology, Harvard University; and Department of EPOBiology, Graduate School and University of Colorado Museum, University ofColorado, for field work during which data and specimens were obtained.Published by permission of the Director, New York State Museum, State Ed-ucation Department, Journal Series No. 298.

Li t e r a t u r e C i t e dB y e , R . A . , Jr . & L . C o n s t a n c e . 1 9 79 . A n e w s p e c i e s o f Tauschia ( U m b e l l i fe r a e ) f r o m C h i h u a h u a ,

M e x i c o . M a d r o f i o 2 6: 4 4 - 4 7 .- - & D . E . S ol t i s . 19 7 9 . Parnassia townsend6 ( S a x if r a g ac e a e ), a M e x i c a n e n d e m i c . S o u t h w .

N a t u r a l i s t 2 4 : 209-222.C o n s t a n c e , L . & R . A . B y e , J r. 1 97 6. N e w C h i h u a h u a n U m b e l l i f e r a e . B o t . M u s . L e a f l. 2 4 : 2 2 5 - 2 4 0 .

AVAILABLEF lo r a o f W e s t P a k i s t a n

Forty-five incomplete sets of the "Flora of West Pakistan" are available forfree distribution. This flora so far consists of 131 published plant families. Eachfamily treatment is a separate part or number having few to many pages. Wewould be glad to send an incomplete set to libraries or individuals who wantthem. Requests should be sent to Plant Taxonomy Laboratory, Pakistan FloraProject , Room 126, Bldg. 001, BARC-West, USDA, Beltsville , MD 20705. Re-questers would have to fill in the remaining plant families by requesting individ-ual numbers from an address to be determined. We could enclose this addressand information along with the sets.