GENERA OF GRASSES OF THE UNITED STATES. 9 
Key to the genera of Festuceae. 
la. Plants dicecious, the sexes very dissimilar, the pistillate lemmas with 
3 long twisted divergent awns, the staminate lemma awnless 
RO TETIRUTLCIOOT) AGC ee SS Be oY Boks Se Be a 30. SCLEROPOGON. 
ib. Plants with perfect flowers, or, if dicecious, the sexes not dissimilar 
EADY GEN AY OYSVE WE OY RSS SI et re TS 2 eee 2 
2a. Lemmas divided at the summit into 5 to several awns or awn- 
Hn Ieuea OPV Shetek Tar 2Ee) EOD (A ES aoe Rn pea 3 
3a. Awnlike lobes 5; inflorescence a simple erect raceme_ 29. ORCUTTIA. 
SUN PN SUAITO Siz OREO Tvs YN OH es cs Se Ee ST 4 
4a. Awns unmixed with awned teeth ; all the florets falling 
attached, their awns forming a pappuslike crown, only 
the lowest floret fertile; panicles narrow_ 32. PaprpopHoRuUM. 
4b. Awns mixed with awned teeth; florets not falling at- 
tached, the rachilla disarticulating between them; 
panicles ‘somewhat openi2202s ee 31. CorTEa. 
2b. Lemmas awanless, with a single awn, or, if 3, the lateral awns 
PUATTULEC eel yee eee RT 8) 0), Se eee 5 
da. Tall stout reeds with large plumelike panicles; lemmas or 
rachilla with long silky hairs as long as the lemmas______ 6 
6a. Lemmas hairy; rachilla naked_____-__~________ 19. ARUNDO. 
6b. Lemmas naked; rachilla hairy______________ 20. PHRAGMITES. 
5b. Low or rather tall grasses, rarely over 5 feet tall__________ iG 
7a. Plants dicecious, perennial; lemmas glabrous; grasses 
OF SaltHrOr alkaline ‘SOUS ees lle DN ee a 8 
8a. Plants low and creeping; spikelets obscure, scarcely 
differentiated from the short crowded rigid 
EC AVC SRE “8 2S SS Se ee eee a 16. MoNANTHOCHLOE. 
8b. Plants erect from creeping rhizomes; spikelets in a 
narrow simple exserted panicle________ 17. DistrcH xis. 
7b. Plants not dicecious (except in a few species of Poa with 
villous lemmas and in an annual species of Eragrostis) — 9 
9a. Spikelets of two forms, sterile and fertile intermixed ; 
panicle dense, somewhat one-sided______________ 10 
10a. Fertile spikelets 2 or 3 flowered; sterile spike- 
lets with numerous rigid awn-tipped glumes; 
panicle dense and spikelike______ 22. Cynosurus. 
10b. Fertile spikelets with 1 perfect floret, long- 
awned; sterile spikelets with many obtuse 
glumes; panicle branchlets short, nodding. 
23. ACHYRODES. 
9b. Spixelets all alike in the same inflorescence_______- 11 
lia. Lemmas 3-nerved, the nerves prominent, often 
Hairy <5. — = — ee aps eee sg eyepiece 12 
12a. Inflorescence a few-flowered head or ecapi- 
tate panicle overtopped by the leaves or 
partly concealed in them ; lemmas toothed 
or cleft; low plants of the arid regions__ 13 
8a. Inflorescence hidden among the sharp- 
pointed leaves, not woolly; plants 
annual (Chlorideae)_- ~----_-- 97. MuNzOA. 
13b. Inflorescence a capitate woolly panicle, 
not concealed; plants perennial____- 14 
