CHAPTER XVII 
Trine V. PANICEA 
SPIKELETS with 1 terminal perfect floret and astaminate 
or neutral floret below; fertile lemma firmer than the 
glumes, often chartaceous; spikelets jointed on the pedicel 
below the glumes. This large and important tribe is, like 
Andropogonez, found mostly in the tropics and warm 
regions, but is well represented throughout the United 
States, especially in the southern portion. The first glume 
is usually absent in the large genus Paspalum and in a 
few other genera, and in Reimarochloa and in certain spe- 
cies of Paspalum the second glume also is absent. In 
Eriochloa the first glume is reduced to a minute ridge 
about the swollen ring-like lower joint of the rachilla. In 
Isachne the lower flower is perfect like the upper. In this 
tribe the spikelets are usually unawned but the glumes 
are awned in Echinochloa, Oplismenus and Cheetium, and 
the lemma in Tricholena. What appear in some genera to 
be awns are bristle-like branchlets. In Chetochloa there 
are 1 or more of these below all or some of the spikelets, the 
bristles remaining after the fall of the spikelets. In Penni- 
setum there is an involucre of bristles (branchlets) sur- 
rounding the base of a cluster of spikelets, the bristles 
being deciduous with the cluster. In Cenchrus the bris- 
tles are retrorsely barbed and fused into a mass, forming 
a bur around the spikelets. An Australian genus, Spinifex, 
is dicecious and Olyra is moneecious. The fruit of Pani- 
cum and of several other genera is a seed-like body con- 
(176) 
