POACEAE. 21 



panicles; pedicels bearing bristles; glumes and lower lemma 

 membranous, the latter often containing a palea and rarely a 

 staminate flower ; upper lemma papery with a similar palea and 

 a perfect flower. 



Chaetochloa viridis (L.) Scribn. Green Foxtail. Annual, usually tufted, 

 green; stems 30-90 cm. high; leaf-blades fiat, 4-10 mm. wide, scabrous on the 

 margins; spikes green, 3-S cm. long, the rachis villous; bristles 1-3, upwardly 

 barbed, 6-12 mm. long; spikelets 2 mm. long; fertile lemma faintly wrinkled. 

 Introduced in fields and waste places. 



32. PANICUM. 



Spikelets with one perfect flower, often with a staminate one 

 below it; glumes 2, membranous; lemmas 2, the lower empty or 

 including the staminate flower, the upper papery, shining, 

 enclosing a similar palea and the perfect flower; awns none (in 

 ours) ; grain free, enclosed in the hardened glume and palea. 



Spikelets acuminate. P. harbipulvinatum. 

 Spikelets obtuse. 



Stems stout; spikelets 3 mm. long P. scribnerianum. 



Stems slender; spikelets 1.8-2 mm. long. P. pacificum. 



Panicum barbipulvinatum Nash. Annual; stems erect or decumbent at 

 the base, 15-SO cm. tall, mostly simple; leaf blades 5-30 cm. long, pubescent; 

 sheaths villous; panicle 10-20 cm. long, the capillary branches solitary or in 

 twos, ascending, branched and spikelet-bearing above the middle; spikelets 

 3 mm. long, ovoid, usually on peduncles as long or longer. In sandy soil, 

 common. 



Panicum scribnerianum Nash. Annual, the stems 10-50 cm. tall, erect 

 or ascending, simple or branched above; stem leaves about 6, the blades lance- 

 olate, 4-10 cm. long, 6-lS mm. wide, stiff, ascending, glabrous or sometimes 

 pilose below; sheaths usually pilose, loose; panicles oblong or pyramidal, 

 3-8 cm. long, loose, exserted or the smaller ones included; spikelets turgid, 

 ovoid, 3 mm. long. Sandy banks of Snake River. 



Panicum pacificum Hitchc. & Chase. Perennial, the stems tufted, 25-50 cm. 

 tall, ascending in the spring and prostrate and spreading in the autumn, 

 branching from the upper nodes, leafy, papillose-pilose with spreading hairs; 

 stem-leaves 5 or 6, the blades erect or ascending, 5-10 cm. long, 5-8 mm. wide, 

 acuminate, narrowed toward the rounded base, papillose-pilose above, ap- 

 pressed papillose-pubescent beneath; sheaths papillose-pilose; panicles usually 

 rather short-exserted, 5-10 cm. long, about three fourths as wide; spikelets 

 1.8-2 mm. long, obovate, obtuse, turgid. Spokane, Kreager. 



33. PHALARIS. 



Annuals or perennials with spike-like or narrow panicles; 

 spikelets crowded, 1-flowered ; glumes 2, about equal, compressed ; 

 lemmas 3, the first two much reduced and sterile, the third 

 enclosing a palea and a perfect flower; stamens 3. 



Panicle very dense, ovoid; glumes wing- keeled. P. canariensis. 



Panicle branched; glumes wingless. P. arundinacea. 



