33 6 GRASS ORDER 



(a) Spikelets 2-many-flowered, the glumes 



lanceolate ELYMUS 



(b) Spikelets 1-flowered, the glumes awl- 



shaped and in a row HORDEUM 



2. Spikelets not in 2 rows in a one-sided or zig-zag 



spike 

 a. Spikelets 2-many-flowered 



(1) Lemma awned from the back 



(a) Spikelets less than 1 cm. long 



x. Lemma fringe-toothed or 2-toothed at 



tip DESCHAMPSIA 



y. Lemma 2-cleft at tip, the teeth awn- 

 pointed 



(x) Awn bent and twisted TRISETUM 



(y) Awn straight or none GRAPHEPHORUM 



(b) Spikelets more than 1 cm. long AVENA 



(2) Lemma awned from the tip or awnless 



(a) Plants dioecious; lemma 3-awned SCLEROPOGON 



(b) Plants not dioecious ; lemma entire or 



2-lobed 



x. Hairs very long and enclosing the lem- 

 ma ; tall swamp grasses PHRAGMITES 

 y. Hairs none or shorter than the lemma 

 (x) Spikelets in the axils of spiny 

 leaves ; stems spreading, 1-4 in. 

 high MUNROA 

 (y) Spikelets not in the axils of spiny 



leaves 

 m. Lemma 1-3-nerved 



(m) Lateral nerves of the lemma 



hairy 

 r. Spikelets appressed on the long 



branches of a panicle DIPLACIINE 



s. Spikelets not appressed on long 



branches TRIODIA 



(n) Lateral nerves not hairy 

 r. Lemma copiously long-hairy at 



base REDFIELDIA 



s. Lemma not long-hairy at base 

 (r) Upper glume much broader 



than the lower EATON i A 



