26 POACEAE. 



Splkelets crowded, 1-flowered. Glumes 5, the first and 

 second about equal in length, strongly compressed later- 

 ally, usually wing-keeled, the third and fourth much 

 smaller or rudimentary, fifth subtending a palea similar 

 to itself and a perfect flower. Stamens 3. Styles dis- 

 tinct. Grain oblong, free, smooth, enclosed in the glumes. 



1. P. minor Retz. Culms simple or somewhat branched, 4-10 

 dm. high, erect or decumbent at the base, smooth; sheaths usually 

 shorter than the internodes, more or less inflated; ligule rounded, 

 2-6 mm. long; blades 5-15 cm. long, 4-10 mm. wide, smooth or 

 faintly scabrous; spike 2-8 cm. long, dense; spikelets 5 mm. long; 

 empty glumes more or less scabrous, 3-nerved, wing- keeled; third 

 and fourth glumes subulate, hairy; fifth twice as long as the third 

 and fourth, acuminate, pubescent with long appressed hairs. 



Very common in all valleys in rather moist or heavy soil. 

 March-May. 



2. P. lemmoni Vasey. Culms rather slender, 3-10 dm. high, 

 smooth; sheaths smooth; blades 3-5 cm, long, acuminate; ligule 6 

 mm. long; spike dense, nearly cylindric, sometimes slightly inter- 

 rupted or lobed; empty glumes 4-5 mm. long, acute or acuminate; 

 second pair about 1 mm. long; flowering glume lanceolate, acuminate, 

 about equaling the empty glumes, pubescent; palea nearly as firm 

 in texture as its glume and a little shorter. 



Desiccated winter pools, Inglewood. 



Tribe 4. AGROSTIDEAE. Bent-grass Tribe. 



Spikelets all hermaphrodite, 1-flowered, with 3 glumes, 

 the first 2 empty or rarely wanting, usually exceeding or 

 equaling the third or flowering glume in length; rachilla 

 sometimes prolonged behind the palea into a naked or 

 plumose bristle. Palea usually 2-nerved. 



Flowering glumes awned or mucronate pointed. 

 Awn of flowering glume terminal or from 

 between the teeth of the bifid apex, 

 sometimes wanting in Epicampes. 

 Awns 3-branched. 9. Aristida. 



Awns simple. 



Awns articulate with the glumes. 

 Awns usually long, geniculate 



and twisted below, persistent. 10. Stipa. 

 Awns short, caducous, or want- 

 ing. 15. Epicampes. 

 Awns not articulate with the glume. 11. Muhlenbergia. 

 Awn dorsal. 



Spikelets articulated with the pedicel 



below the empty glumes. 16. Polypogon. 



