316 
1. Spikelets heterogamous or rarely homogamous, the joints 
of the axis of the raceme (false spike) appressed or 
grown to the pedicels of the primary spikelets, forming 
a hollow or excavation for the reception of the secondary 
spikelets ; fertile glumes always awuless. 
2. Spikelets 2-nate ; first empty glume flat (12) RotthoeUia 
2. Spikelets 2-nate: first empty glume globose (13) Manisuris 
2, Spikelets solitary; first empty glume convex (14) Ophiurua 
1 . Spikelets heterogamous, the sessile hermaphrodite, rarely 
pistillate, the pedicellate staminate, empty or wanting, 
very rarely all hermaphrodite or all pedicellate ; joints 
of the racemes not strongly thickened, nor with excava- 
tions for the reception of the spikelets. 
2. Sessile spikelets 2-flowered. 
3. Racemes reduced to the terminal joint with 
three spikelets, and enclosed by a sheath- 
ing leaf or bract (17) Apluda 
3, Racemes with many joints. 
4. Spikes rarely solitary : spikelets 2- 
flowered, awned (15) Ischaemuni 
4. Spikes solitary ; spikelets 1-flowered, 
the first glume pectinate (16) Eremochloa 
2. Sessile spikelets 1-flowered. 
3. A false whorl of four or more staminate or 
empty spikelets at the base of each raceme ; 
racemes usually subtended by a sheathing 
leaf (20) Thcmcda 
3. No distinct whorl of staminate or empty 
spikelets at the base of the racemes, or 
where an imperfect one occurs, the ra- 
cemes in pairs, subtended by a leaf-sheath, 
4. Fertile glume awned from the back 
or base; leaves cordate at the base.. (18) Arthraxon 
4. Fertile glumes awned from the apex 
or from a more or less deep cleft, 
or awnless ; leaves not cordate at 
the base (19) Andropogon 
Tribe nr. Z0ISIE.$. 
1 . Spike slender ; spikelets narrow ; first and second glumes 
awned (21) Perotis 
1, Spike rigid: spikelets appressed to the rhachis, not awned.. (22) Zuisia 
Trilie IV. TRISTEGINE^:. 
1 , Flowering glumes of the hermaphrodite flowers awned ; 
awns usually geniculate and twisted below ; slender 
grasses (23) Arundinella 
1, Flowering glumes awnless ; spikelets minute ; very coarse 
■grasses (24) Thysanolaeiia 
Tube V. PANICE.®. 
1. Spikelets all perfect. 
2. Spikelets without any special covering or involucre 
consisting of spines or bristles. 
3. Empty glumes two ; perfect flower one in 
each spikelet. 
4. Lower empty glume with a thickened 
ring-like callus (27) Eriocliloa 
4. Lower empty glume without a ring- 
like and thickened callus ; spikelets 
in one-sided racemes or spikes. 
5. Spikelets ovate or orbicular, 
obtuse, rarely acute (25) Paspalum 
5. Spikelets lanceolate, acute or 
acuminate (26) Digitaria 
