POACEAE. 25 



Cinna latifolia (Trev.) Griseb. Stems solitary or few, erect, 60-120 cm. 

 high; leaf blades flat, green, 1-1.5 cm. broad, scabrous; panicle pale green, 

 drooping, 10-30 cm. long; glumes subequal, scabrous, 4 mm. long; lemma 

 shorter, scabrous, bearing a short straight awn; palea 2-nerved. In moist 

 places in woods. 



41. SPOROBOLUS. 



Annuals or perennials with small 1 -flowered spikelets; inflo- 

 rescence an open contracted panicle; glumes membranous, the 

 first somewhat shorter; lemma membranous, equalling or longer 

 than the glumes; grain free and often deciduous. 



Panicle open, branches mostly spreading. S. cryptandrus. 



Panicle contracted, spike-like. 



Glume one-third to one-half the length of the lemma. 5. richardsoni. 



Glume from two-thirds to almost the whole length of the 



lemma. 5. depauperaius. 



Sporobolus cryptandrus (Torr.) Gray. Stems 50-100 cm. tall, erect, 

 usually simple, smooth; leaf blades flat, becoming involute, 10-15 cm. long, 

 3-4 mm. wide; ligule minute; sheaths long, bearded at the throat; panicle 

 erect, narrowly pyramidal, 10-20 cm. long, its base enclosed in the uppermost 

 sheath; branches mostly in pairs, ascending; spikelets crowded, leaden-colored, 

 1.5 mm. long. Sandy bars of Snake River. 



Sporobolus richardsoni (Trin.) Merrill. Somewhat tufted; stems very 

 slender, 20-50 cm. high, minutely roughened; ligule acute, 2 mm. long; 

 panicle small; spikelets 3 mm. long, acute; lemma cuspidate. Medical Lake, 

 Henderson. 



Sporobolus depauperatus (Torr.) Scribn. Densely matted, 10-15 cm. high; 

 stems strongly decumbent at base; leaf blades 5-8 cm. long, narrow, involute, 

 minutely scabrous; stem leaves 4-5; ligules entire, acute; panicle very narrow, 

 2-5 cm. long, erect, frequently with its base in the uppermost sheath; spikelets 

 2-2.5 mm. long; lemma acuminate, scabrous above. In low swales, common. 



42. CALAMAGROSTIS. 



Tall perennial grasses with small spikelets in many-flowered 

 terminal panicles; spikelets 1-flowered, the pubescent rachilla 

 prolonged behind the palea; glumes subequal, longer than the 

 lemma which is hyaline and obtuse, and bears a dorsal awn; 

 callus copiously hairy; palea shorter; grain free, enclosed in the 

 lemma. 



Awn strongly geniculate; callus hairs much shorter than the 



lemma; panicle dense. C. rubescens. 



Awn straight; callus hairs not much shorter than the lemma. 

 Panicle loose; leaf-blades soft. 



Glumes 2-2.5 mm. long. C. macouniana. 



Glumes 3-4 mm. long. C. canadensis. 



Panicle narrow, rather close. 



Leaf-blades soft, not stiff. C. neglecta. 



Leaf-blades stiff. C. hyperborea. 



