Fragilegrass

Aegopogon unisetus (Lag.) R. & S. Syst. Veg. 2 : 805. 1817
Hymenothecium uniseium I^ag. Gen. Sp. PI. 4. 1816.
Schellingia tenera Steud. Flora 33 : 232. 1850.
Aegopogon geminiflorus "BoVim. Mex. PI. Gram. 71. 1881. '^ot A. geminiflorus '^.'^.'K,. 1815.
Aegopogon geminiflorus purpureus Qris^h.; Fourn. Mex. PI. Gram. 71. 1881.
Aegopogon gem.iniflorus unisetus Fourn. Mex. PI. Gram. 71. 1881.
Aegopogon geminiflorus aboriivusVoyxrrs.. Mex. PL Gram. 71. 1881.
Stems up to 5 dm. long, slender; leaf -sheaths smooth and glabrous; blades usually 1-6 cm. long, rarely 1 dm., 1-3 mm. wide, glabrous -beneath, commonly puberulent on the upper surface or rarely glabrous and scabrous; inflorescence 2-6 cm. long, often interrupted below; spikelet-clusters 3-4 mm. long, exclusive of the awns and the hispid peduncle, of 3 spikelets on hispid pedicels, the sessile or short-pedicellate spikelet perfect, the others empty; empty scales obovate, obovate-cuneate, or cuneate, 2-lobed at the apex with rounded or truncate lobes, 1-nerved, rarely awnless, the nerve usually extending a^ a hispidulous awn shorter than the scale, or rarely equaling it; flowering scale of the perfect spikelet 3-nerved, 3-lobed and 3-awned at the apex, the midnerve running out into a hispidulous awn usually longer than the spikelet, rarely shorter, the lateral lobes subulate and extending into short awns, and sometimes with a minute tooth at the base of the awn, the lobes rarely obtuse and merely awn-pointed, the flowering scale of the other spikelets with the lobes rounded and muticous, rarely awn-pointed, or the lobes rarely resembling those of the perfect spikelet.
Type locality : Mexico. Distribution : Arizona to Guatemala.

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 cm. long; spikelet-clusters 2-2.5 mm. long, exclusive of the pedtmcle, 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 rudimentary; 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, October 15, 1887, C. G. Pringlel408 (herb. Columbia Univ.). Distribution : Known only from the type locality.

Annuals, Terrestrial, not aquatic, Stems trailing, spreading or prostrate, Stems nodes swollen or brittle, Stems geniculate, decumbent, or lax, sometimes rooting at nodes, Stems caespitose, tufted, or clustered, Stems terete, round in cross section, or polygonal, Stems branching above base or distally at nodes, Stem internodes hollow, Stems with inflorescence less than 1 m tall, Stems, culms, or scapes exceeding basal leaves, Leaves mostly cauline, Leaves conspicuously 2-ranked, distichous, Leaf tips flexuous, drooping, blades thin, lax, soft, Leaves sheathing at base, Leaf sheath mostly open, or loose, Leaf sheath smooth, glabrous, Leaf sheath hairy, hispid or prickly, Leaf sheath and blade differentiated, Leaves borne on branches, Leaf blades linear, Leaf blades very narrow or filiform, less than 2 mm wide, Leaf blades mostly flat, Leaf blades mostly glabrous, Leaf blades more or less hairy, Ligule present, Ligule an unfringed eciliate membrane, Inflorescence terminal, Inflorescence a dense slender spike-like panicle or raceme, branches contracted, Inflorescence solitary, with 1 spike, fascicle, glomerule, head, or cluster per stem or culm, Inflorescence a panicle with narrowly racemose or spicate branches, Inflorescence single raceme, fascicle or spike, Inflorescence branches 1-sided, Flowers bisexual, Spikelets sessile or subsessile, Spikelets laterally compressed, Spikelet less than 3 mm wide, Spikelets with 1 fertile floret, Spikelets 3 per node, Spikelets bisexual, Inflorescence disarticulating between nodes or joints of rachis, rachis fragmenting, Spikelets falling with parts of disarticulating rachis or pedicel, Spikelets secund, in rows on one side of rachis, Rachilla or pedicel g labrous, Glumes present, empty bracts, Glumes 2 clearly present, Glumes equal or subequal, Glumes shorter than adjacent lemma, Glumes 1 nerved, Lemmas thin, chartaceous, hyaline, cartilaginous, or membranous, Lemma similar in texture to glumes, Lemma 3 nerved, Lemma glabrous, Lemma apex dentate, 3-5 fid, Lemma distinctly awned, more than 2-3 mm, Lemma with 1 awn, Lemma with 3 awns, Lemma awn less than 1 cm long, Lemma awn 1-2 cm long, Lemma awned from tip, Lemma awns straight or curved to base, Lemma margins thin, lying flat, Lemma straight, Palea present, well developed, Palea membranous, hyaline, Palea about equal to lemma, Palea 2 nerved or 2 keeled, Palea keels winged, scabrous, or ciliate, Stamens 3, Styles 2-fid, deeply 2-branched, Stigmas 2, Fruit - caryopsis, Caryopsis ellipsoid, longitudinally grooved, hilum long-linear.