GRIFFITHS—-THE GRAMA GRASSES. 
Spikelets not pectinately arranged.¢ (Subgenus 
ATHEROPOGON.) 
Spikes of 1 spikelet..............0.2.0..2.222.. .. 35. 
Spikes of more than | spikelet. 
Plants annual. 
Leaves and sheaths tuberculate-hairy.... 18. 
Leaves and sheaths not  tuberculate- 
Plants perennial. 
Sheaths densely hairy.......-........--- 20. 
Sheaths not densely hairy. 
Glumes densely hairy. 
Sterile lemma trifid, long-awned. 21. 
Sterile florets two or three, with 
well developed lemmas 
(variable)..............-- 22. 
Glumes not densely hairy. (See 
continuation. ) 
(Continuation.) 
Sterile florets distinctly 2 or more. 
Plants stoloniferous ........2220..0..00.000. 002020020200 23. 
Plants cespitose. 
Plants low, hairy..................-.22-2.-.--20-------- 24. 
Plants tall, smooth................22..2..-----2------ 25. 
Sterile floret 1 or with additional rudimentary one. 
Second floret trifid and naked, not glumaceous. 
Lateral awns short. 
Second floret glumaceous. 
Second floret mostly perfect, the first sterile. 
Plants smooth ...............22--22---222-22+--+-- 29 
Plants more or less prominently papillose-hairy. 
Spikes and spikelets alike (Continental Amer- 
ica). 
Plants stout with harsh rhizomatous base. 30. 
Plants more delicate, cespitose or genicu- 
late... 2... eee eee ee eee eee 31 
Spikes and spikelets very variable (West 
Indies)................-222-2---+---- 32 
Second floret sterile, the first fertile. 
Spikes about 12............22------ 33 
Spikes more numerous, 
Spikelet with rudiment of a third 
floret.......-2.........-.. 34 
Spikelet with no rudiment of a 
Land 
m ees) 
ee) 
eo 
353 
. uniflora. 
. alamosana. 
. aristidoides. 
. pringlei. 
. chondrosioides. 
. eludens. 
. megapotamica. 
. texana. 
. lophostachya, 
. acuminata, 
. vaneedeni. 
. americana. 
. Fepens. 
B. radicosa, 
. B, filiformis. 
. B. heterostega. 
. B. disticha. 
. B, pilosa, 
third floret............... 36. B. curtipendula. 
a@Tmmature forms of several species belonging here are likely to be looked for 
under Chondrosium. 
