174 BULLETIN 772, U. S. DEPARTMENT OF AGRICULTURE. 
bearing at the base a tuft of long hairs, bifid at the apex, the mid- 
nerve extending as a short awn. 
Our species is a low, tufted perennial, with capillary blades and 
slender solitary spikes, the spikelets somewhat distant. Species about 
nine, Kast Indian and African except one American. 
Type species: Tripogon bromoides Roth. 
Tripogon Roth; Roem. and Schult., Syst. Veg. 2: 
600. 1817. Only one species described. 
The American species, Tripogon spica- 
tus (Nees) Ekman (Leptochloa spicata 
Seribn.) (fig. 102), is found on sterile hills 
# in Texas and northern Mexico, Cuba, 
and South America. It is of no im- 
} portance agriculturally. 
v 84. Exeusrne Gaertn. 
1, Spikelets few to several flowered, 
compressed, sessile and closely im- 
/ bricate, in two rows along one side 
of a rather broad rachis, the latter 
not prolonged beyond the spikelets; 
rachilla disarticulating above the 
Fie. 102.—Tripogon spicatus. Plant, <x 4; spikelet and floret, x 5. 
glumes and between the florets, glumes unequal, rather broad, acute, 
1-nerved, shorter than the first lemma; lemmas acute, with 3 strong 
green nerves close together forming a keel, the uppermost somewhat 
reduced; seed dark brown, roughened by fine ridges, loosely inclosed 
in the thin pericarp. 
Annual grasses, with two to several rather stout spikes, digitate 
at the summit of the culms, sometimes with one or two a short dis- 
