72 POACEAE 



1. D. glomerata L. Stem 6-12 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 fruit; lemma 5-6 mm. long, pointed or short-awned. 

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

 Mont. Je-Jl. 



62. BRIZA L. QUAKING GRASS, QUAKE-GRASS. 



Annuals or perennials, with open panicles. Spikelets fe\v, nodding, flattened, 

 broad, many-flowered, the flowers perfect. Empty glumes strongly 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 spikelets 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 58 mm. wide; their floral glumes about 2 mm. wide in side-view: palet 



distinctly dentate on the margins; leaf-blades usually over 2 mm. 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; palet 4-5 mm. long; panicle 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. spicata Coult & Nels., 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 plant 4-8 

 cm. long, 2-2.5 cm. wide; spikelets 1-2 cm. long, 5-8 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, with paniculate inflorescence. Spike- 

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

 articulate between the flowers. Empty glumes persistent, 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, as well as the rachis, the hairs near the base sometimes long 

 and curled (cobweb). 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 and P. lanata, and usually 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. 



