MANUAL OF THE GRASSES OF THE UNITED STATES 469 



excurrent (variable in a single spike) ; fertile spikelet about equaling 

 the lateral ones, its narrow glumes deeply cleft into few to several 

 acuminate ciliate lobes and slender awns; lemma scarcely exceeding 

 the glumes, thin, ciliate, 2-lobed, the midnerve excurrent into a short 

 awn. % (Pleuraphis rigida Thurb.) — Deserts, southern Utah and 

 Nevada to southern California and Sonora (fig. 1007). 



89. AEGOPOGON Humb. and Bonpl. 



Spikelets short-pedicellate, in groups of 3, the group short-pedun- 

 culate, spreading, the peduncle disarticulating from the axis and 

 forming a pointed stipe below the group, this falling entire; central 

 spikelet shorter pedicellate, fertile, the 2 lateral ones longer pedi- 

 cellate and staminate or neuter; glumes membranaceous, notched at 

 the apex, the midnerve extending into a delicate 

 awn; lemma and palea thinner than the glumes, 

 extending beyond them, the lemma 3-nerved, the 

 central nerve and sometimes also the lateral 

 ones extending into awns, the palea 2-awned. 

 Low, lax annuals, with short, narrow, flat blades 

 and loose racemes of delicate groups of spike- 



i , m a L ' J Figure 1007.— Distribution of 



lets, lype species, Aegopogon cenc/iroiaes miana rigida. 



Humb. and Bonpl. Name from Greek aix, goat, 



and pogon, beard, alluding to the fascicle of awns of the spikelets. 

 1. Aegopogon tenellus (Cav.) Trin. (Fig. 1008.) Culms 10 to 

 20 cm long, usually spreading or decumbent; blades 1 to 2 mm wide; 

 racemes 3 to 5 cm long; spikelets, excluding awns, about 2 mm 

 long; lemma and palea of lateral spikelets broad and rounded at 

 summit with a single delicate awn, those of the fertile spikelet nar- 

 rower, with one long and 2 short awns, o — Open ground, moun- 

 tains of southern Arizona and south to northern South America. 



TRIBE 7. CHLORIDEAE 



90. LEPTOCHLOA Beauv. Spraxgletop 



Spikelets 2- to several-flowered, sessile or short-pediceled, approxi- 

 mate or somewhat distant along one side of a slender rachis, the 

 rachilla disarticulating above the glumes and between the florets; 

 glumes unequal or nearly equal, awnless or mucronate, 1 -nerved, 

 usually shorter than the first lemma; lemmas obtuse or acute, some- 

 times 2-toothed and mucronate or short-awned from between the 

 teeth, 3-nerved, the nerves sometimes pubescent. Annuals or 

 perennials, with flat blades and numerous usually slender spikes or 

 racemes borne on a common axis forming a long or sometimes short 

 panicle. Type species, Leptochloa virgata. Name from Greek leptos, 

 slender, and chloa, grass, alluding to the slender spikes. 



The only species of Leptochloa important as a forage grass is L. 

 dubia, or sprangletop, of the Southwest, useful for grazing and for 

 hay. 



Plants perennial. 



Lemmas broad, notched at apex, the lateral nerves glabrous 1. L. dubia. 



Lemmas acute or awned, the lateral nerves pubescent. 



Lemmas about 3 mm long; panicle flabellate, the axis short. 



2. L. CHLORIDIFOKMIS. 



