POACEAE. 39 



scabrous, the loose sheaths exceeding the internodes; panicle narrow, 10-30 

 cm. long, the densely-flowered branches mostly solitary and erect; spikelets 

 nearly orbicular, flattened, 2 mm. long. In shallow water or very moist 

 places. 



61. AGROPYRON. WHEATGRASS. 



Perennials with simple stems and terminal spikes; spikelets 

 3-many-flowered, sessile, single and alternate at each notch of 

 the usually continuous rachis, the side of the spikelet, that is the 

 edge of the glumes toward the rachis; lemmas rigid, rounded 

 on the back, 5-7-nerved, usually acute or awned at the apex; 

 palea often with hairy keels; grain pubescent at the apex. 



Plants densely tufted, seldom producing stolons. 



Spikelets subterete, the florets close; lemma short-awned. A. tenenim. 

 Spikelets flattened, the florets loose; lemma usually awned. 



Glumes awnless. A. spicatum. 



Glumes awned. A.flexuosum. 



Plants producing abundant stolons. 



Lemma puberulent. A. lanceolatum 



Lemma glabrous. 



Leaves pale, scabrous above; nerves prominent. A. ocddentale. 



Leaves green, pubescent above; nerves rather obscure. A. repens. 



Agropyron tenerum Vasey. Perennial, tufted; stems erect, 30-100 cm. 

 high, rather slender, glabrous; stem leaves 3 or 4, the blades becoming in- 

 volute, scabrous on both sides; the sheaths glabrous and shorter than the 

 internodes; spike 10-20 cm. long, narrow, the spikelets densely crowded; 

 lemmas linear-oblong, 5-nerved, scabrous, acuminate or short-awned. 

 Common in low ground. 



Agropyron spicatum (Pursh) Scribn. & Smith. Wheat Bunch-grass. Stems 

 50-100 cm. tall, densely tufted, glabrous and glacuous; stem leaves 3, the 

 blades becoming strongly involute, minutely pubescent above, scabrous 

 beneath, the sheaths smooth or pubescent; spikes erect, 5-15 cm. long; 

 spikelets regularly scattered, lanceolate-oblong, 10-20 mm. long, without 

 the awns; lemma tipped with a stout divergent awn, 1-2 cm. long. Very 

 abundant on dry hills and exposed edges. Under some conditions, the plants 

 produce long stolons. 



Agropyron spicatum inerme (Scribn. & Smith) Heller. Stems usually 

 more slender; spikelets smaller; awns wanting. Very abundant on dry hills 

 and exposed ledges. The species and the subspecies are frequently found 

 growing together. 



Agropyron flexuosum Piper. (Sitanion flexuosum Piper.) Very similar 

 in appearance to A. spicatum. Spikelets looser, flexuous; spikelets often two 

 at a node; glumes awned, often trifid; lemma usually bifid, its awn 3.5-4 cm. 

 long. Banks of Snake River at Wawawai. 



Agropyron lanceolatum Scribn. & Smith. Stems erect, 60-120 cm. tall, 

 smooth, from elongated creeping rootstocks; stem leaves 4, the blades becoming 

 involute, rather narrow, ascending, strigose above, smooth beneath, the sheath 

 loose, exceeding the internodes; spikes erect, 15-25 cm. long; spikelets not 

 crowded, 2-2.5 cm. long, 6-10-flowered; lemmas sparsely pubescent, tipped 

 with a very short awn. Common on the dry sandy bars of Snake River. 



Agropyron occidentale Scribn. Bluestem. Whole plant pale or glaucous; 

 stems erect, 30-100 cm. high; leaves firm, the nerves thick and prominent; 



