138 NORTH AMERICAN FLORA [VoLUME 17 
33. AEGOPOGON H. & B.; Willd. Sp. Pl. 4: 899. 1806. 
Hymenothecium Lag. Gen. Sp. Pl. 4. 1816. 
Schellingia Steud. Flora 33: 231. 185 
Annual grasses, with slender ae and the spikelets borne in clusters in a 1-sided raceme- 
like inflorescence. Spikelet-clusters of 2 or 3 spikelets, rarely more, one spikelet sessile or 
short-pedicellate, perfect, the others on longer pedicels, staminate, empty, or rudimentary. 
Empty scales awned or awnless, 1-nerved, usually 2-lobed or 2-toothed at the apex, 
the teeth or lobes rounded or truncate at the summit, acute or acuminate, the empty 
scales rarely lanceolate and acute or only obscurely toothed at the apex. Flowering scales 
3-nerved, 3-toothed or 3-lobed at the apex, the teeth or lobes obtuse, or more commonly 
acute or acuminate, often awned, the midnerve sometimes barely excurrent, but usually 
extending into a long awn; palets 2-nerved, the nerves usually extending intoawns. Stamens 
3. Styles distinct. Stigmas plumose. 
Type species, Aegopogon cenchroides H. & B. 
Empty scales lanceolate, entire, or rarely obscurely toothed at the apex ; spike- 
let-clusters 2-2.5 mm. long, exclusive of the peduncle. 1. A. imperfectus. 
Empty scales manifestly 2-toothed or 2-lobed at the apex; spikelet-clusters 
2.54 mm. long, exclusive of the awns and peduncle. 
Lobes of the empty scales acute or acuminate. 
Nerves of the empty scales extending into an awn not more than twice as 
long as the scale ; spikelet-clusters 3-4 mm. long. 2. A. cenchroides. 
Nerves of the empty scales extending into an awn 3-4 times as long as the 
scale; spikelet-clusters 2.5-3 mm, long. 3. A. breviglumis. 
Lobes of the empty scales rounded or truncate at the apex. 4. A. unisetus. 
1. Aegopogon imperfectus Nash, sp. nov. 
Stems up to 2 dm. long, very slender; leaf-sheaths smooth and glabrous; blades 1-4 cm. 
long, up to 1 mm. wide, glabrous beneath, puberulent on the upper surface; inflorescence 3-4 
em. long; spikelet-clusters 2-2.5 mm. long, exclusive of the peduncle, of 2 spikelets, one perfect, 
the other rudimentary, or sometimes a third spikelet present consisting of a pedicel and a 
minute scale; empty scales of the perfect spikelet 1-nerved,. lanceolate and acute, or rarely 
obscurely 2-toothed and shortly awned, those of the other spikelets very small and often rudi- 
mentary; flowering scale of the perfect spikelet 3-nerved, 3-toothed at the apex, the nerves 
sometimes slightly excurrent, the flowering scale of the other spikelets rudimentary. 
Type collected_on cool mossy ledges, Arroyo Aucho, Sierra Madre, Chihuahua, Mexico, Oc- 
tober 15, 1887, C. G. Pringle 1408 (herb. Columbia Univ.). 
DISTRIBUTION: Known ouly from the type locality. 
2. Aegopogon cenchroides H. & B.; Willd. Sp. Pl. 4: 899. 1806. 
Aegopogon geminifiorus H.B.K, Nov. Gen. & Sp. 1: 133. 1815. 
Hymenothecium trisetum Lag. Gen. Sp. Pl. 4, 1816. 
Hymenothecium quinguesetum Lag. Gen. Sp. Pl. 4. .1816. 
Aegopogon trisetus R. & S. Syst. Veg. 2: 805. 1817. 
Aegopogon quinqueselus R. & §. Syst. Veg. 2: 805. 1817. 
? Aegopogon selifer Nees, Linnaea 19: 691. 1847, 
? Aegopogon multiselus Steud. Syn. Gram. 146. 1854. 
? Aegopogon rigidisetus Steud. Syn. Gram. 146. 1854. 
Aegopogon cenchroides abortivus Fourn. Mex. Pl. Gram. 72. 1881. 
Aegopogon cenchroides multisetus Fourn. Mex. Pl. Gram. 72, 1881. 
Aegopogon gracilis Vasey, Bull. Torrey Club 13: 230. 1886. 
Stems 1-5 dm. tall, slender; leaf-sheaths smooth and glabrous; blades up to 1 dm. long, 
usually flat, 1-2 mm. wide, glabrous beneath, puberulent on the upper surface; inflorescence 
2-8 cm. long, sometimes interrupted below; spikelet-clusters 3-4 mm. long, exclusive of the 
awns and hispid peduncle, of usually 3, or sometimes 2, spikelets on hispid pedicels, the 
sessile or short-pedicellate spikelet perfect, the others staminate or empty, one often 
reduced in size; empty scales strongly scabrous, linear to oblong or cuneate, awned from 
the 2-lobed apex, the awn from shorter than to longer than the scale, rarely twice its 
length, the lobes very short, deltoid and merely acute to subulate, awned and one half as 
long as the scale or more; flowering scales 3-nerved, 3-lobed and 3-awned at the apex, the 
