32 POACEAE 



Lemma obtuse. 



Stem bulbous at the base. 



Panicle narrow; lemma 7-8 mm. long. 



Spikelets usually nodding, flattened; second empty glume shorter than 

 the first flower. 4. M. spectabilis. 



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. Orchard-grass. i. D. qlomeraia. 



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



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



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



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. 



Branches of the inflorescence in fruit refle.xed or at least spreading; lemma 

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

 Spikelets many, Ught green; branches of the inflorescence numerous, the 



lower in 3's" or 4's, or 5's; rootstock creeping. III. PL.\TYPHyLLAE. 



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. Reflexae. 



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. Apertae. 

 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. Alpixae. 

 Spikelets acute at the ba.se; 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. Wheeleri.\xae. 



Spikelets not stronglv compressed; lemma neither strongly compressed 



nor strongly nerved (e.xcept in P. pra(fns!/o/-wis), not conspicuously 



scabrous. 



Lemma acuminate, dark purple; innovations extravaginal. 



X. Phoenice.\e. 

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

 tions both extra- and intra vaginal. XI. Aridae. 

 Plants without extravaginal rootstocks; densely tufted bunch-grasses. 

 Lemma 3-4 mm. long. 



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



lemma ovate. XII. RUPICOLAE. 



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

 lanceolate in side-view. XIII. ISIultnomae. 



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. Gracillimae. 



Pubescence of the nerves of the lemma viUous 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. Anxuae. 

 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. Bigelovii. 



II. Pratenses. 

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



Lemma 5 mm. long; ligule not truncate. 4. P. rhizomata. 



