3 
I. Panicle loose, the branches not sessile. 
* Outer glumes membranaceous or narrow and rigid, with 2 prominent lateral 
4 gia, 
NETVES .. 0222 2 ee ee ee ee ee cee eens CHRYSOPOGON, 9 
** Outer glumes when in fruit hard, smooth, and shining .......-..SORGHUM, 13 
II. Panicle strict, the branches sessile. 
* Spikelets in pairs, awned, both perfcct....-.....---+----0------- ERIANTHUS, 8 
** Spikelets in pairs, awnless......-. 222-24. - eee eens eee eee eee eee IMPERATA, 8 
3. Tribe ZOYSIAE. 
Spikelets in groups of two to five, usually 1-flowered, the tlowering 
glume always awnless, membranaceous; the empty glumes of firmer 
texture and frequently awned. 
A. Two outer spikelets male, each 2-flowered, the inner spikelet perfect, 
1-flowered .-.--. 22 ce ee ee eee cere ee cee eee teen eee eee wees HILARIA, 13 
B. Lowest spikelet of each group sterile, terminal one fertile, 1-flowered, with 
delicate glumes . .....-.--.-----+----+----2- --- 2 eee eee eee ZEGOPOGON, 14 
C. Uppermost spikelet of each group sterile, second empty glume coriaceous, 
with hooked spines on the back....-..--..------.-.+..--.---.TRaGUS, 15 
4, Tribe PANICE A. 
Spikelets 1- or occasionally 2- flowered, the second flower male or 
neutral (very rarely perfect) in the axis of the third glume, arranged in 
spikes, racemes, or panicles; flowering glume and palet of the perfect 
flower always firmer in texture than the empty glumes, unawned; 
empty glumes rarely awned. 
A. Spikelets all perfect (hermaphrodite), neither sunken in an excavation in the 
rachis nor subtended by a large leaf-sheath. 
I. Empty glume 1........---- +2226 eee eee eee eee ce eee eee eee eee REIMARIA, 15 
II. Empty glumes 2; perfect flowers single. 
* Spikelets with a swollen, ring-like callus at the base......-...- ERIOCHLOA, 21 
** Spikelets without a swollen callus at the base. 
+ Spikelets sessile, or nearly so, in one-sided spikes, these frequently in pairs or 
panicles.........2.. 2-2 e222 ee eee ee eee cee ee ee eee eee PaspaLuM, 15 
+ Spikelets not sessile in one-sided spikes, but in panicles, and pedicellate. 
(a) All the spikelets alike in terminal panicles............ ANTHZNANTIA, 20 
(b) Spikelets of two kinds; first, the sterile, borne on a terminal panicle; 
second, the fertile, borne on short subterranean branches. 
AMPHICARPUM, 20 
II. Empty glumes 3, perfect flowers 1, or a flowering glume with male flowers instead 
of the third empty glume. 
* First and second empty glumes without a distinct callus, awnless. . -PaNIcUM, 22 
** First and second empty glumes awned............----..----- OPLISMENUS, 37 
IV Spikelets single or in pairs, subtended by an invelucre consisting of from one to 
many bristles or spines (sterile branches), which are sometimes grown together. 
* Spikelets falling at maturity; bristles persistent.......... 22.2.2... SETARIA, 37 
** Involucral bristles falling off with the spikelets at maturity. 
+ Bristles numerous, rigid, thickened at the base, frequently grown together. 
CENCHRUS, 39 
£ Bristles usually numerous, apparently whorled, delicate, not thickened at the 
base, often plumose ...... 0.2.22. 0.020. cece eee eee eee eee PENNISETUM, 39 
B. Spikelets without bristles, sunken into cavities of the one-sided broad rachis of 
the short spikes...... 0.2... 2.22 cee ee eee eee eee cee eee STENOTAPHRUM, 40 
