406 



CONTRIBUTIONS PROM THE NATIONAL HERBARIUM. 



in size upward, the last sometime." faced by a small 1-awned scale, the whole so 

 congested ae to appear like a bunch of awns, and borne upon a short, naked stipe 

 about 1 mm. long; caryopsis 1.25 mm. long, ovate, flattened on the back, the very 

 small scutellum covering only one-fourth or one-fifth of the ventral surface. (Fin- 

 ure 54.) 



In general appearance, especially as to inflorescence this species resembles Lep- 

 tochloa, but the floral characters are those of Bouteloua. The basal portion of the 

 plant resembles that of Muhleribergia pungens Thurb. 



HERBARIUM SPECIMENS. 



South America: Stuchert 10277a, in Herb. Argent.; 694, in Kneucker's Gram. Exs. 

 from Argentina. Elliott 510, Chile. Benivati 12687 in Kurtz, Herb. Argent. 



26. Bouteloua acuminata (Fourn.). 



Aiheropogon acuminatus Fourn. Mex. PI. 2 : 139. 1881. The specimens cited, 

 Liebmann 583, from Mirador, and Liebmann 584, from Potrero de Consoquitla, Mex- 

 ico, have not been exammed. My knowledge of the species is based upon Palmer's 

 no. 1655, concerning the identity of which there appears to be no doubt. 





description. 



A stout, erect, smooth, cespitose perennial, resembling B. curtipendula in habit 

 and general appearance; culms erect, comparatively stout, about 50 cm. high, leafy 



to the top, mostly unbranched; sheaths striate, 

 close; blades broad, flat, often 5 mm. wide and 

 25 cm. long, striate, smooth with serrate edge, 

 and conspicuous, long, dusky, papillose hairs on 

 the upper surface at the base, the ligular mem- 

 brane with a few scattered hairs of the same 

 nature; panicle racemose, often 25 cm. long; 

 spikes numerous, 30 to 60, distinctly bilateral 

 but the peduncles so curved as to appear 

 unilateral toward maturity; spikelets 6 to 15, 

 loosely and indistinctly or not at all pectinate, 

 consisting of 1 floret and a rudiment; glumes 

 hispid, keeled, the first acuminate, about 2 

 mm. long, the second Bhort-awned, about 3 

 mm. long; lemma minutely pubescent, shortly 

 3-aristate, the central awn 0.5 mm. or less 

 longer than the lateral, about 4 mm. long; 

 palet, acuminate, smooth, about 2.5 mm. long; 

 rudiment reduced to a single, hispid, delicate 

 awn, about 1.5 mm. long; caryopsis not seen. (Figure 55.) 



In general habit this very closely resembles B. curtipendula, but the spikes are 

 very different, although exactly the same in arrangement'. They are smaller and 

 apparently more numerous. Indeed, one might describe the species as B. curti- 

 pendula with small delicate spikes of rather loosely arranged spikelets, only a fourth 

 the size of those of that well-known species. 



Palmer's 1655, cited above, of which there are two sheets in the National Herba- 

 rium, is from Lodiego, Sonora, Mexico, collected October 9 to 15, 1891. It is said 

 to grow in large bunches on the mountain sides. 



Fig. 55.— Bouteloua acuminata, a, Spikelet; 

 b,c, lemma and palet of first floret; d, rudi- 

 ment, a, Scale 7.5; b-d, scale 10. From 

 Palmer 1655. 



