32 POACEAE 



Lemma obtuse. 



Stem bulbous at the base. 



Panicle narrow, lemma 7-8 m.m. long. 



Spikelets usually nodding, flattened; second empty glume shorter than 

 the first flower. 4. M. spectaMlis. 



Spikelets erect, terete; second empty glume as long as the first flower. 



5. M. bella. 

 Panicle open; lemma 6 mm, long. 6. M. Macbridei. 



Stem not bulbous at the base. 7. M. Porteri. 



61. DACTYLIS L. Oechard-gkass. l. D. glomerala. 



62. BRIZA L. QuAKiNn Grass, Quake-grass. l. B. maxima. 



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

 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 mm. wide. 2. D. dentata. 



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



Annuals, but tufted ; spikelets 3-5-fiowered. I. Anntjae. 



Perennials. 



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

 acuteoracutish, except in P. compressa and f.Tanafa, 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. 



Branches of the inflorescence in fruit reflexed or at least spreading; lemma 

 usually acuminate or very acute; cobweb scant or sometimes none. 

 Spikelets many, light green; branches of the inflorescence n ume rous, the 

 lower in 3's, or 4's, or 5's; rootstock creeping. III. Plattphtllae. 



Spikelets few, usually more or less purple, except in P. leptocoma; branches 

 of the inflorescence few, the lower usually in 2's, rarely in 3's, spikelet- 

 bearing towards the ends. IV. Kefleixae. 



Intermediate nerves of the lemma faint or obsolete. 



Stem compressed; lemma obtuse. V. Compressae. 



Stem not compressed; lemma acute or acuminate. 



Branches of the panicles reflexed; rootstock creeping. VI. Apehtae. 

 Branches of the panicles not reflexed. VII. Triflorae. 



Cobweb wanting. 



Spikelets rounded at the base; empty glumes very broad and their keel strongly 

 arched; low tufted perennials, with short open panicle and broad leaves. 



VIII. Alpinae. 

 Spikelets acute at the base; empty glumes narrower, not strongly arched on their 

 keels. 

 Plants with horizontal creeping rootstocks; not bunch-grasses. 



Spikelets strongly compressed; lemma, strongly keeled, strongly 5-nerved, 



conspicuously scabrous; glumes very acute. IX. Wheelerianae. 



Spikelets not .strongly compressed; lemma neither strongly compressed 



nor strongly nerved (except in P. pra(enst/ormts), not conspicuously 



scabrous. 



Lemma acuminate, dark purple; innovations extravaginal. 



X. Phoeniceae. 

 Lemma obtuse or acutish, green or merely tinged with purple: innova- 

 tions both extra- and intravaginal. XI. Aridae. 

 Plants without extravaginal rootstocks; densely tufted bunch-grasses. 

 Lemma 3-4 mm. long. 



Low alpine plants, with narrow panicles of few purplish spikelets; 



lemma ovate. XII. Rupicolae. 



Slender plants, 4—5 dm. high, with open panicles; lemma narrowly 

 lanceolate in side-view. XIII. Multnomae. 



Lemma 5 mm. long or more; plants comparatively robust. 



Spikelets decidedly flattened; lemma acute and keeled on the back. 

 Pubescence on the nerves of the lemma, if any, not stronger than 

 ^ on the internerves; flowers perfect. 



Inflorescence dense and spike-like. XIV. Epile.s. 



Inflorescence open: branches spikelet-bearing towards their 

 . ends. XV. Graoillimae. 



Pubescence of the nerves of the lemma villous or pilose, that of the 

 internerves none or almost none; plants dioecious. 



XVI. Fendlerianae. 

 Spikelets little flattened; lemma rounded on the backs towards the 

 apex, almost straight, obtuse. XVII. Buckleyanae. 



I. Anntjae. 

 Low, 1-2 dm. high; branches of the panicle spreading. 1. P. annua. 



Taller, erect, 2-5 dm. high; branches of the panicle erect. 2. P. BigelovH. 



II. Pratenses. 

 Lemma 3-4 mm. long; ligule truncate. 3. p. pratensis. 



Lemma 5 mm. long; ligule not truncate. 4. p. rhizomala. 



