15 
Tripe I1.—ANDROPOGONE. 
Spikelets in spike-like racemes, two at each joint of the articulate 
rachis, one sessile and hermaphrodite, one pedicellate, the latter 
hermaphrodite, staminate, neuter, or reduced to the pedicel alone; 
glumes usually four, the first and second empty, larger and much 
piamninBte Bow: er in its ah abut rarely awned, the fourth or flower- 
, awn usually twisted or geniculate. 
This tribe contains bai four hundred species. divided 
among twenty-nine genera, of which the genus Andro- 
pogon, with one hundred and ninety species, is by far 
the largest and probably the most important. Sugar- 
cane belongs to this tribe in the genus Saccharum. 
Our best-known representatives of the Andropogonex 
are the common broom sedge, Andropogon virginicus, 
and the big blue stem, Andropogon provincialis. In 
the same genus are now classed the many varieties of | 
ghum. The members of the tribe are distributed 
throughout the tropical and warmer temperate regions 
of both hemispheres. 
KEY TO THE GENERA OF THE ANDROPOGONE*, 
At Asie of the spikes or racemes hairy; fertile glumes usually 
awned ve 
1. Axis of the spikes or racemes deceige: fertile glumes awnless.. 6 
2. Spikelets all alike (homo ) 5 
2. Spikelets not all alike iebsteeaaiais} 7 
3. ral axis continuous - 4 
3. Floral axis articulated 5 
4, Panicles dense; Reset awnless - ee ee ee 5. Imperata 
ga 3 slet: d. 6, MiscanTaus 
5. Spikelets awned 8. ERIANTHUS 
5. Spikelets awnless 7. SAccHARUM 
6. First empty glume of the a sth men Agena otstageta or 
somewhat convex .....----------------+++--- . Max ne 
6. First empty glume of the I phrodite spikelet hard 
ular, pitted externally _ 10. HAacKELocHLoa 
. Rachis imperfectly articulated; primary spikelet on a short 
pedicel, awnless; secondary spikelet agernred and long 
awned ke CHYPOGON 
yA os aitnctly articulate; coarse el fas ae 8 
8. 8 t isk 12. Exronvrvs 
a = -..s+c--- 13. ANDROPOGON 
~~ 
