72 POACEAE 



1. D. glomerata L. Stem (5-12 dm. high, smooth; leaf-blades 7-25 cm. 

 long, 2-6 mm. wide, flat, scabrous; panicle 7-20 cm. long; branches ascending or 

 spreading in flower, erect in fniit; lemma 5-6 mm. king, pointed or short-awned. 

 Fields and waste places: N.B. — Fla. — Calif. — B.C.; nat. from Eu. Plain — 

 Mont. Je-Jl. 



62. BRIZA L. QuAKiNc Gr.\ss, Quake-grass. 



Annuals or perennials, with open panicles. Spikelets few, nodding, flattened, 

 broad, many-flowered, the flowers perfect. Empty glumes strong!}- concave, 

 thin-membranous, 3-5-nerved, somewhat unequal. Lemmas imbricate, broader 

 than the empty glumes, 5-many-nerved. Palet much shorter, hyaline, 2-keeled 

 and 2-nerved. Styles distinct; stigmas plumose. 



1. B. maxima L. Stem 3-5 dm. high, glabrous; leaf-blades 1-2 dm. long, 

 3-6 mm. wide, scabrous on the veins; spikelets 2-10, nodding, 1-2 cm. long, 

 8-12 mm. wide; empty glumes nearly orbicular, glabrous; lemma similar, but 

 more or less pilose. Fields and waste places: Mass. — W. Ind. — Colo. — Calif.; 

 adv. from Eurasia. Plain — Submont. 



63. DISTICHLIS Raf. Alkali Grass, Salt-grass, Spike-grass. 



Tufted dioecious perennials, with creeping scaly rootstocks. Inflorescence 

 paniculate. Staminate sj^ikelets many-flowered, very flat. Rachilla continu- 

 ous. Empty glumes narrow, acute, keeled, membranous. Lemma broader, 

 membranous. Pistillate spikelets few-flowered, less flattened. Lemma nearly 

 coriaceous, broad. Palet compressed, the keels narrowly winged. Styles 

 thickened at the base, moderately long; stigmas plumose. 



Pistillate spikes 4-5 mm. wide; their floral glumes about 1.5 mm. wide in side-view; 



palet scabrous-ciliate on the keels; leaf-blades 2 mm. wide or less. 1. D. stricta. 



Pistillate spikes 5-8 mm. wide: their floral glumes about 2 mm. wide in side-view: palet 



distinctly dentate on the margins; leaf-blades usually over 2 ram. wide. 2. D. dentata. 



D. stricta (Torr.) Rydb. Stem 1-4 dm. high, erect or decumbent at the 

 base; leaf-blades erect, 5-15 cm. long, more or less involute, long-attenuate; 

 panicle of the pistillate plant 3-6 cm. long, dense and spike-like; spikelets 8-15 

 mm. long; empty glumes lanceolate, acuminate, about 5 mm. long; the second a 

 little broader than the first, scarious-margined ; lemma 5-6 mm. long, acute, 

 straw-colored with greenish nerves; ])alet 4-5 mm. long; ])anicle of the staminate 

 plant looser, 3-10 cm. long; spikelets more flattened, 1-2.5 cm. long, straw- 

 colored; lemma narrower, 6-7 mm. long. D. sjncata Coult & Xels., not Greene. 

 Alkaline soil: Sask. — Tex. — Ariz. — B.C. — Wash. Plain — Submont. Je-S. 



2. D. dentata Rydb. Stem 1-3 dm. high, very leafy; leaf-blades 5-12 cm. 

 long, 2-3.5 mm. wide, flat or slightly involute; panicle of the pistillate j^lant 4-S 

 cm. long, 2-2.5 cm. wide; spikelets 1-2 cm. long, 5-S mm. wide, 7-17-flowered; 

 empty glumes lanceolate, about 5 mm. long, short-acuminate; lemma ovate in 

 lateral view-, 6 mm. long, short-acuminate; palet nearly as long; panicle of stam- 

 inate plant nearly as in the preceding. Alkaline soil: Sask. — Wash. 



64. POA L. Blue-grass, Meadow-grass. 



Annuals or perennials, rarely dioecious, w-ith paniculate inflorescence. Spike- 

 lets 2-6-flow-ered, flat, the flowers perfect or in some species unisexual, the rachis 

 articulate between the flowers. Empty glumes j)ersistent, strongly keeled, acute, 

 the first usually 1-nerved, the second 3-nerved. Lemma usually longer, more 

 or less keeled, acute or obtuse, awnless, .5-nerved, often pubescent on the keel 

 and marginal nerve, at well as the rachis, the hairs near the base sometimes long 

 and curled (cobw-eb). Palet shorter than the lemma, 2-keeled and 2-nerved. 

 Styles short; stigmas plumose. 



Annuals, but tufted; spikelets 3-5-flowered. I. Annuae. 



Perennials. 



Cobweb at the base of the lemma present, although scant in some species; lemma 

 acute or acutish, except in P compressa a,nd P. lanata, andusually strongly keeled. 

 Intermediate nerves of the lemma strong. 



Branches of the inflorescence in fruit ascending, the lower in 3's or 4's; lemma 

 acutish; cobweb copious; rootstock creeping. II. Pratenses. 



