GRIFFITHS THE GRAMA GRASSES. 



357 



HERBARIUM SPECIMENS. 



Mexico: Nelson 2940, Chiapas. 

 Guatemala: Eeyde & Lux 423, Santa Rosa. 



2. Pentarrhaphis polymorphs (Fourn.). 



Atheropogon polymorphus Fourn. Mex. PL 2: 141. 1881. A few spikes of the 

 type before me identify this plant perfectly. Fournier had smaller plants, however, 

 than any in the U. S. National Herbarium, as indicated by a photograph of the speci- 

 mens in the herbarium of the Museum at Paris. 



Bouteloua fourneriana Vasey; Wats. Proc. Amer. Acad. 22: 461. 1887. A name 

 only. 



Pentarrhaphis fourneriana Hack. & Scribn. Bull. Torrey Club 17: 229. pi. 107, 108. 

 1890. Pringle's no. 2559 in U. S. National Herbarium is a duplicate of the type. 



Pentarrhaphis geminata Hack. & Scribn. Bull. Torrey Club 17 : 230. 1890. A name 

 only. 



DESCRIPTION . 



An erect, smooth, cespitose perennial, about 30 cm. high, with the habit of well- 

 developed plants of B. trinii, but larger throughout; culms mostly erect, but in some 



Fig. 21. — Pentarrhaphis polymorpha. a, Spike displayed; 6, c, lemma and palet of first floret; d, e, 

 lemma and palet of second floret, a, Scale 5; b-e, scale 7.5. From Pringle 2559. 



specimens inclined to be slightly geniculate; upper blades sparse, flat, and short, 

 the lower more abundant and longer, 5 to 10 cm. long and about 1 mm. wide, bearing 

 a few minute, scattered hairs on both surfaces; sheaths striate, smooth, narrow, the 

 ligule reduced to a cilia te fringe; panicle racemose, the rachis wavy or zigzag; spikes 



4 to 8, triangular, 6 to 10 mm. long, purplish in all the specimens at hand; spikelets 

 with backs together, 2-flowered, the lower floret pistillate, the upper staminate, with 

 a bifid or undivided awn-like rudiment of a third; glumes narrow, the lower reduced 

 to little more than an awn about 4 mm. long, the upper wider, keeled, notched above, 



5 to 6 mm. long; lemma 5 to 6 mm. long, including the 3 nearly equal awns, the glumes 

 and lower lemma covered with white hairs 1 mm. long; palet 3 to 4 mm. long, deeply 



