PIPER—FLORA OF THE STATE OF WASHINGTON, 103 
Lemma awaless or short-awned, and loosely enveloping the grain. 
Inflorescence a dense spike. 
Spikelets early deciduous; lemma with a dorsal awn... ALorgecurus (p. 110). 
Spikelets persistent; lemma awnless or with a terminal 
awn. 
Spikes ovoid; glumes long-awned.......-------- Potypogon (p. 111). 
Spikes cylindric; glumes not long-awned... .-- -- - PuHvievo (p. 111). 
Inflorescence a loose panicle. 
Fruit a utricle.........-.-.-.--------------------- Sprorosotus (p. 112), 
Fruit a grain. 
Palet 1-nerved; stamen 1.........-.----------- Cinna (p. 113). 
Palet 2-nerved; stamens 3. 
Glumes none; plant, minute ........-..---- CoLEANTHUS (p. 114). 
Glumes 2. 
Callus with a tuft of long hairs at base... CaLaMaGrostis (p. 114), 
Callus naked. ..........-.--------+--- Acrostis (p. 118). 
AVENEAE, 
Perfect flower only one, the other staminate. 
Lower flower perfect; upper staminate and awned......--.- Houcus (p. 121). 
Lower flower staminate, long-awned; second flower perfect, 
awnless .......------------2 22-22-22 ee eee eee ARRHENATHERUM (p.121). 
Perfect flowers 2 or more. 
Rachilla not prolonged beyond the upper flower. ..-..----- Aira (p. 121). 
Rachilla prolonged beyond the upper flower. 
Awn of the lemma arising between the two terminal 
teeth... 2222-2222 eee eee MERATHREPTA (p. 122). 
Awn of the lemma dorsal. 
Florets large, more than 15 mm. long... .----.--- AVENA (p. 123). 
Florets small, less than 15 mm. long. 
Lemma erose-truncate.........------------ Descuampsia (p. 123). 
Lemma 2-toothed ._.......-.------------- TRISETUM (p. 124). 
FESTUCEAE, 
Lemma 3-nerved, rarely 1-nerved. 
Raghilla with long hairs.......-...-----------------+--- PHRAGMITES (p. 125). 
Rachilla glabrous or with short hairs. 
Glumes obtuse, very unlike, the upper inclosing the 
flowers. .......--------------------- 2-22 ee eee Estonia (p. 125). 
Glumes subequal, acute. 
Panicle close; spikelets 2 to 4-flowered .......--- KoeE ceria (p. 126). 
Panicle loose; spikelets usually many-flowered. ... KRaGRostis (p. 126). 
Lemma 5-nerved or more. 
Spikelets with the upper florets sterile and folded about each 
other .... 2222-22-22 22 ee eee ee eee ee eee Metica (p. 127). 
Spikelets with the upper florets perfect, or narrow and abor- . 
tive. 
Keels of the palea winged... ....------------------- PLEuROPOGON (p. 128). 
Keels of the palea not winged. 
Stigmas arising below the apex of the ovary... -- Bromus (p. 141). 
Stigmas arising at the apex of the ovary. 
Lemmas compressed and keeled. 
