30 
Trine [1V.—TRISTEGINE®. 
Spikelets all ide sone in panicles; aor glumes three, 
or with a staminate flower in its axil, herbaceous or 
chartaceous; flowering nents aatianuemok awned or awnless; 
rachilla. setae below the empty glumes 
A small tribe of only seven genera and thirty-three 
species, natives chiefly of the tropical regions of the 
Old World. Of the few American species none extend. 
so far north as the United States. 
Tripe V.—PANICE. 
Spikelets hermaphrodite, terete or flattened on the back; glumes 
three or four (rarely only two); when four, there is occasionally a 
eng ae flower or a palea in the axil of the third; the upper- 
ost or aed ering glume of the hermaphrodite flower is always 
ies n texture than the outer eee of which the first is 
ory pana than the others; axis the inflorescence not 
articulated, the rachilla being articulated aha the empty glumes, 
the gpikelats falling off singly from their pedicels. 
This is one of the largest tribes in the order Grami- 
nee. It contains twenty-two genera with over six hun- 
dred and thirty species. Panicum, the principal genus, 
is the largest among grasses, numbering three hundred 
species. The Panicew are very widely distributed 
throughout the tropical and temperate regions of the 
world. Crab grass and the millets are among our best 
known examples of this tribe. 
KEY TO THE GENERA OF THE PANICE. 
i. ee | EY yt «i é, 4} e fe rtile 
on short, leafless, subterranean, branches. . 21. Astrucanres M 
1. Spikelets 
2. Spikelets half imbedded in the flattened axis of the spike-like 
panicle ie OTAPHRUM 
2. Spikelets not sunken in excavations along the main axis .... 3 
3. Spikelets subtended or surrounded by one to many bristles or 
_ spines which are distinct or more or less connate below... 4 
3. Spikelets not surrounded by a bristly or spiny involucre .... 6 
