250 



MISC. PUBLICATION 200, U. S. DEPT. OF AGRICULTURE 



Culms numerous in a close tuft, the leaves mostly basal; lemmas mostly awn- 

 less 12. E. SALINUS. 



Culms few, loosely tufted, the leaves scattered along the usually taller culms; 



lemmas awn-tipped, the awn 2 to 5 mm. long 11. E. ambiguus. 



Lemmas awned, the awn as long as the body or longer. 



Awns straight; lemmas about 1.2 mm. wide across the back. 



20. E. VILLOSUS. 

 Awns flexuous-divergent ; lemmas about 2 mm. wide across the back. 



21. E. INTERRUPTUS. 



4b. Glumes lanceolate or narrower, broadened above the base, strongly 3- to several- 

 nerved. 

 Glumes relatively thin, flat, several-nerved, not indurate at base. 

 Lemmas sparsely long-hirsute on the margins toward the summit. 



17. E. HIRSUTUS. 

 Lemmas glabrous or scabrous. 



Lemmas awned 15. E. glaucus. 



Lemmas awnless or minutely awn-tipped 16. E. virescens. 



Glumes firm, indurate at base. 



Awns divergently curved when dry; base of glumes not terete. 



22. E. CANADENSIS. 



Awns straight; base of glumes terete. 



Glumes about 1 mm. wide about the middle, the bases not bowed out; palea 



much shorter than the lemma 23. E. riparius. 



Glumes 1.5 to 2 mm. wide about the middle, the bases bowed out; palea as 



long as the lemma - 24. E. virginicus. 



Figure 332. — Elyrnus caput-medusae, X 1. (Vasey 3076, Wash.) 



1. Elymus caput-medusae L. (Fig. 



332.) Annual; culms ascending from 

 a decumbent, branching base, slen- 

 der, 20 to 60 cm. tall; blades narrow, 



short; spike very bristly, 2 to 5 cm. 

 long (excluding the long spreading 

 awns); glumes subulate, smooth, in- 

 durate below, tapering into a slender 



