24 POACEAE. 



38. ALOPECURUS. 



Annuals or perennials; inflorescence a spike-like panicle; spike- 

 lets 1 -flowered, flattened; glumes acute, sometimes short-awned; 

 lemma 3-nerved, awned on the back, usually with a palea. 



Awns scarcely exceeding the glumes; spikelets 2 to 2.5 mm. 



long. A . geniculatus. 



Awns much exceeding the glumes. 



Spikelets 3 mm. long; anthers orange. A. calif ornicus. 



Spikelets 4 mm. long; anthers white. A. saccatus. 



Alopecurus geniculatus fulvus (Smith) Sender. Pale green and glabrous 

 or nearly so; stems decumbent and branched at base, 15-60 cm. long; leaf 

 blades flat, somewhat scabrous above; sheaths little inflated; panicles slender, 

 erect, 3-7 cm. long; spikelets 2.5 mm. long; glumes ciliate on the keels; lemma 

 shorter than the glumes, bearing a short awn. In wet places, often partly 

 floating. 



Alopecurus californicus Vasey (A. pallescens Piper). Perennial, tufted, 

 pale green, the smooth stems 30-50 cm. tall, erect or slightly geniculate at 

 the base; stem leaves 3; sheaths rather loose and inflated, shorter than the 

 internodes, smooth; blades flat, 6-12 cm. long, 2-6 mm. wide, acuminate, 

 strongly scabrous above, less so beneath; ligule scarious, 3-5 mm. long; 

 panicle usually well exserted, pale and silvery, 2-7 cm. long, about 5 mm. 

 thick, erect, straight or somewhat flexuous; glumes 2-5 mm. long, nearly 

 equal, strongly ciliate on the keels, obtuse; lemma hyaline, 2-4-nerved, as 

 long as the glumes, obtuse, bearing from near the base a stout geniculate awn, 

 5 mm. long, scabrous above the bend. Common in wet places. 



Alopecurus saccatus Vasey. Pale green, glabrous, simple or tufted, 10-30 

 cm. high, erect or geniculate at base; sheaths much inflated, about as long as 

 the internodes; ligule well developed; blades short, 2-8 cm. long, 2-4 mm. 

 broad; panicles usually exserted, 2-5 cm. long, thick, pale green or purplish; 

 glumes strongly ciliate on the keels; lemma shorter than the glumes and bearing 

 a divergent awn 6-7 mm. long. In moist ground, local. 



39. POLYPOGON. 



Annual grasses; inflorescence a spike-like panicle; spikelets 

 1-flowered; glumes each extended into an awn; lemma smaller, 

 generally hyaline, short-awned, with a palea which is shorter 

 than the lemma; grain free, enclosed in the lemma and palea. 



Polypogon monspeliensis Desf. Annual, with erect or ascending stems, 

 8-30 cm. high; leaf blades flat, more or less scabrous; sheaths loose, shorter 

 than the internodes; spike-like panicle densely flowered, oblong, rarely inter- 

 rupted, 2-7 cm. long; empty glumes elliptic, notched at the apex, about 2 mm. 

 long, bearing terminal awns 3 or 4 times as long; flowering glume truncate, 

 1 mm. long, bearing a terminal awn somewhat longer. Moist places, especially 

 where somewhat alkaline. 



40. CINNA. 



Tall perennial grasses with flat leaves, conspicuous hyaline 

 ligules and usually many-flowered nodding panicles; spikelets 

 1-flowered; rachilla articulated below the glumes and prolonged 

 behind the palea into a minute bristle; glumes narrow; lemma 

 3-5-nerved; palea 1 -nerved; stamen 1. 



