248 



POACEAE 



Species about 45 in the temperate regions of the northern hemisphere. Type species, Elymus sibiricus L. 



Plants annual. 1- £• cafut-medusae. 

 Plants perennial. • 

 Creeping slender rhizomes present. 



Glumes lanceolate. o c ;r 



Glumes about 2 cm. long, lemmas distinctly nerved. 2. h. mollis. 



Glumes 1-1.5 cm. long; lemmas faintly nerved, or distinctly so only at apex. 



3. E. z'ancoiirci-eiisii 



Glumes subulate or very narrow. 

 Lemmas glabrous. 

 Lemmas pubescent. 

 Pubescence short. 

 Pubescence woolly. 

 Creeping rhizomes wanting (short and thick in E. condciisatiis). 

 Glumes subulate. 



Plant cinerevis-pubescent. 



Plant glabrous or scabrous, or rarely pubescent but not cinereus. 

 Glumes lanceolate or narrower, nerved, not subulate. 

 Glumes and lemmas acuminate or awn-pointed. 

 Sheaths pubescent. 

 Sheaths glabrous. 

 Glumes and lemmas awned. 



Lemmas sparsely ciliate above; glumes several-nerved; spikes interrupted. 



10. E. hirsutns. 

 Lemmas glabrous or variously pubescent but not ciliate above. 

 Glumes not indurate at base. 



Spike slender and dense, about 5 mm. thick; blades narrow, mostly 2-4 mm. wide; 



glumes narrow, faintly nerved. 11. E. macounii. 



Spike stouter, about 8-10 mm. thick, if slender then not dense; blades usually 5-10 mm. 

 wide; glumes broader, distinctly nerved. 12. E. glaiicits. 



Glumes indurate and usually divergent at base. 



Awn short and straight; glumes bowed out, the induration at base prominent, usually 



yellow; spikes erect. 13. E. virginicus submuUcus. 



Awn long and spreading; glumes divergent but not much bowed out at base, the indura- 

 tion less conspicuous; spike nodding. 14. £. canadensis. 



4. E. triticoides. 



5. £. arenicola. 



6. E. flavescens. 



7. E. cinereus. 



8. E. condcnsatus. 



12a. E. glaucns jepsoni. 

 9. £. I'iresccns. 



1. Elymus caput-medusae L. 



Aledusa Head. 



Fig. 589. 



Elymus caf^ut-incdiisae L. Sp. PI. 84. 1753. 



Annual ; culms branched at base, erect or de- 

 cumbent at base, slender, 20-60 cm. tall ; blades 

 narrow and short ; spike 2-5 cm. long, long-awned ; 

 glumes awl-shaped, smooth, indurate below, nar- 

 rowed into a slender awn 1-2.5 cm. long ; lemmas 

 lanceolate, 3-nerved, 6 mm. long, flat, very scabrous, 

 gradually narrowed into a flat awn, 5-10 cm. long. 



Open ground, Washington to California, infrequent; intro- 

 dticed Irom Europe. June-July. Type locality, European. 



2. Elymus mollis Trin. 



Sea Lyme-grass. Fig. 



590. 



1821. 



1830. 



Illrnius mollis Trin. in Spreng. Neu. Entd. 2: 72. 

 El'vmus dives Presl, Rel. Haenk. 1: 265. 1830. 

 El'viniis arcnarius villostis E. Mey. PI. Labrad. 20. 

 El'vmus ampliculmis Provancher, Fl. Canad. 2: 706. 1862. 

 Elymus capitatus Scribn. U. S. Dept. Agr. Div. Agrost. Bull. 11: 



" 55. pi. 14. 1898. ^ „ 



Elymus rillosissimus Scribn. V. S. Dept. Agr. Div. Agrost. Bull. 



■ 17: 326. /. 622. 1899. 

 Elymus arenarius mollis Koidzumi, Journ. Coll. Sci. Tokyo 27: 



"24. 1910. 

 Elymus arcnarius compositus St. John, Rhodora 17: 102. 1915. 



Culms stout, smooth, or pubescent above, glaucous, 

 60-120 cm. tall from creeping rhizomes; sheaths and 

 blades smooth or the latter scabrous above; spike erect, 

 dense, 7-25 cm. long; glumes lanceolate, flat, many- 

 nerved, scabrous or pubescent, 12-25 cm. long, acumi- 

 nate, awnless, about as long as the spikelet ; lemmas 

 about as long as glumes, scabrous or felty-pubescent, 

 acuminate or mucronate. 



Sand dunes along the coast, Alaska to Santa Cruz, California; also Labrador to Maine, and along the 

 Great Lakes. June-Aug. Type locality : Kamchatka. 



