GRIFFITHS — THE GRAMA GRASSES. 



417 



symmetrical; glumes scabrous-keeled, the first reduced nearly to an awn, 5 mm, 

 long, the second wider, 7 to 8 mm. long; lemma 5 to 6 mm. long, smooth, with 3 short 

 awns, the lateral awns slightly longer than the central; upper floret simply a 3-awned 

 rudiment with a few scales at base or a well-developed perfect floret, but always, 

 except in the lower spikes, bearing a long central awn, the lemma, including awn, 

 10 to 14 mm. long, the lateral awns often not more than 6 or 7 mm. long. (Figure 60.) 



The first specimen of this species which I have recognized is Schott 741, in the 

 herbarium of the Field Museum of Natural History. The floral characters of B. 

 disticha are exceedingly variable, as is true of 

 many of the species of this group. The descrip- 

 tion is drawn from the upper spikelets. The 

 lower ones are small and often staminate only, 

 the rudiment being reduced to three imperfectly 

 developed, short awns. 



The species is exceedingly rare in collections. 

 The chief diagnostic character is the inflorescence 

 and the apparent bilateral arrangement of the 

 spikelets, which is admirably brought out in 

 Kunth's figures. 



Besides the Schott specimen the following are 

 typical: Curtiss 537, from Cuba; Pittier 10374, 

 from Costa Rica; and Le6n 299, from Cuba. Pittier 

 2537, Canal Zone, is a geniculate form with branch- 

 ing culms. 



34. Bouteloua pilosa (Hook.) Benth. 



Eutriana pilosa Hook. f. Trans. Linn. Soc. Bot. 

 20: 173. 1851; Steud. Syn. PI. Glum. 1: 216. 

 1854. The Macrae specimen from Albemarle 

 Island, cited by Hooker, has not been examined. 

 My knowledge is based upon Andersson 46, from 

 Galapagos, and Fendler 2521, from Venezuela, in 

 the Grisebach Herbarium. More recently many 

 fine specimens have been examined in the Gray 

 Herbarium from the Hopkins Galapagos Expedi- 

 tion (Snodgrass & Heller 655). 



Eutriana gracilis Hook. f. Trans. Linn. Soc. Bot. 

 20: 175. 1851, not Bouteloua gracilis Hook. a nor 

 Lagasca. & The type of this species has been 

 examined through the courtesy of the director 

 of the Royal Botanic Gardens of Kew, England. 



Bouteloua -pilosa Benth.; Wats. Proc. Amer. Acad 

 Eutriana pilosa Hook. f. 



DESCRIPTION. 



Fig. 61.— Bouteloua pilosa. a, Spikelet; 

 6, c, lemma and palet of first floret; 

 d, rudimentary second floret; e, rudi- 

 mentary floret of lowermost spikelet; 

 /, two views and cross section of cary- 

 opsis. a, Scale 5; b-f, scale 10. From 

 Snodgrass & Heller 655 in Gray Herb. 



18: 179. 1883. Based upon 



An erect, cespitose, smooth annual(?) 20 to 40 cm. high; culms slender, often 

 branching; sheaths close; blades flat, thin, often 10 cm. long, the ligule an incon- 

 spicuous ring of short hairs; inflorescence racemose, 10 to 20 cm. long; spikes vari- 

 able, from 15 to 35, bilateral, on a zigzag rachis, but usually appearing unilateral; 



a Vasey in Wheeler, Rep. U. S. Surv. 100th Merid. 6 : 287. 1878. 

 & Steud. Norn. Bot. ed. 2. 1 : 219. 1840. 



