100 



POACEAE 



Lemma scabrous or glabrous. 



Emptj- glumes lanceolate, acuminate or short-awned, 2-5-nerved 

 Spike dense: spikelets more or less imbricate. 



Plants not tufted, with rootstocks; leaf-blades spreading. 



Sheaths and blades glabrous; glumes scabrous, at least above, 



oi ^1. ^ , ^ 10. E. glaucus. 



b heaths and lower leaf-blades pubescent; glumes glabrous. 



_,, ^ ^ , 11. ^. marginalis. 



o ./ l^^t^ tufted; leaf-blades ascending. 12. E, nitidus, 



&pike lax; spikelets distant; glumes glabrous. 13. E. Petersonii. 

 Kmpty glumes linear-subulate. 



Spike 7-8 mm thick; awns 30-40 mm. long. 14. E. Saundersii. 



vSpike 5 mm. thick; awns 5-10 mm. long. 15. E. Macounii. 

 Lemma awnless or short-awned; awn less than one-third the length of the body. 

 Empty glumes strongiy 3-5-nerved. 



Empty glumes thickened and strongly curved at the base, not scarious-margined. 



^ . , .,, ^, , . 16. E. curvatus. 



Ji^mpty glumes neither thickened nor strongly curved at the base, more or less 

 scarious-margmed. 17 F Houelln 



Empty glumes 1-nerved or indistinctly 3-nerved 

 [.emma glabrous or hispid ulous. 



Empty glumes aristiform or narrowly subulate. 



Plant stout. 1-2 m. hi-h, tufted; spikelets 2-6 at each joint; lemma scab- 



rous-hispidulous. 18. e, condensatus. 



Plant slender, ,^-io dm. hi^h; spikelets 1 or 2 at each joint. 



Lemma broadly lanceolate, acute or awn-pointed; rachis scabrous on 



the sharp angles; spikelets erect; plant with a horizontal root- 

 stock. 19 E triticoides. 

 Lenima narrowly lanceolate; rachis nearlv terete, strigose; plant tufted, 

 fepikelets usually in pairs; lemma awn-pointed. 



Lemma glabrous. 20. E. ambiguus. 



Lemma scabrous or scabro-strigose. 21. E. sirigosus, 



Spikelets usually singly; lemma acuminate or acuce. 



TTi™ *. , , , 22. E, salinus. 



Ji-mpty glumes lanceolate-subulate, tapering from the rather broad base; 

 lemma glabrous. o^ p vimnUr 



Lemma pubescent. ^^- ^- ^^""'P^^^' 



Plants tufted; lemma long-attenuate, short-awned. 24. E. villi florus. 



±'iants not tufted, or somewhat so in E. cinereus, with horizontal rootstocks; 



lemma not long-attenuate. 

 Lemma appressed-pubescent. 



Stem, sheath, and leaves glabrous or minutely strigulose. 

 e+^^ ... ^ , 25. E. arenicola. 



t™ • sheath, and leaves densely short pubescent. 26. E, cinereus. 

 Lemma with spreading pubescence. 



Spike long; empty glumes lanceolate. silky-viUous. 



27, E ffQV€SC€TlS' 



Spike short; empty glumes subulate, scabrous. 28! e\ innovatus. 



virginicus L. Stem 6-10 dm. high; sheath usually glabrous; leaf- 



4 dm Ifinor d—1f\ mm «ir;j-^ „„„U .•!__ p 1 I- 7 .1 • 1 ».. 



5-15 cm. long, thick, erect; 



^'^"^^tS"^ ^- ^°^cf glabrous; awn scabrous' 5-18 mm. long. Along streams! 

 ^.S.— Fla.— Tex.— Sask. Plain. Je-Au. . 



1 o ^' 1 ^®J"i^"3 (Ramaley) Rydb. Stem slender, 3-G dm. high; leaf-blades 

 1-2 dm. long 2-5 mm. wide, scabrous; spike 2-6 cm. long, strict; spikelets usually 



2 at each node; lemma lanceolate, 7-8 mm. long, scabrous, hispidulous; awn 3-10 

 mm. long. _ A. wr^rimcus minor Vasey. E. virginicus jejunus Ramaley. Sand 

 hills and nver banks : Minn.-Neb.-Wyo.-Mont. Plain-Siihmont. J^Au. 



3. E. diversiglumis Scribn. & Ball. Stem 9-12 dm. high, glabrous; leaf- 

 blades spreading, Lo-2.5 dm. long, 6-12 mm. wide, scabrous on both sides; 



wit; f/^Q^^"^' 2-flowcred; lemma linear-lancoolate, acute, 8-10 mm. long, 

 mdistinctly 3-5-nerved hirsute or scabrous, hispidulous; awn 2-3 cm. long. Rich 

 open places: ^\ls.— Wyo.— N.D. Plain—SuLont. Jl. 



Inn.f'Aff^"'^*^®'^!'^ L. Stem 6-15 dm. high, glabrous; leaf-blades 1-3 dm. 

 H;nl'c;^ri iT' ^'»de scabrous; spike 1-3 dm. long, usually long-exscrted. nod- 

 ronfi.^ p' ^*' spreadmg, 3-5-flowered ; lemma 8-14 mm.long; awn 2-5 cm.long, 

 SifcmoHf Jl-Au "^ ^"'"''^ bushes: N.S.— Ga.— N.M.— B.C. Plain 



9 J.^^r^\ ^°^^^*o^^ Scribn & Smith. Stem 1-2 m. high, smooth; leaf-blades 

 i nm tV- f^' ^t20 mm^'ide, scabrous on both sides; spike 12-18 cm. long, 2.5- 

 4 cm. thick; spikelets 3-4 at the nodes, 3-4-flowered; lemma 12-lG mm long, 



