194 BULLETIX 772, TT. S. DEPARTMENT OF AGRICULTURE. 
Three species are annuals, B. aristidoides Thurb., B. procumbens 
(Durand) Griffiths (B. prostrate Lag.), and B. barbata Lag. (B. 
pohjstachya Torr.). These are found from Texas to Arizona, where 
they are called six-weeks grama. They furnish forage when young, 
but are of secondary importance. 
For a revision of the spe- 
cies of Bouteloua and it- 
allies, see Griffiths, Contr. 
U. S. Nat. Herb. 14:343- 
424. 1912. Economic notes 
and synonymy are included. 
96. Cathestecvm Presl. 
Spikes consisting of 3 
spikelets, the upper or cen- 
tral perfect, the 2 lateral 
staminate or rudimentary, 
the spike falling entire; 
central spikelet with one 
perfect floret below and one 
or more reduced florets 
above; glumes unequal, the 
first a short, thin, nerveless 
scale in the central spikelet, 
narrow and acuminate in 
the lateral spikelets, the 
second about as long as the 
lemma, acuminate, all usu- 
Fig. 114. — Blue grama, Bouteloua gracilis. Plant. X 
glumes, floret with rudiment, and floret alone, X 5. 
ally villous; lemma 3-nerved, or rarely 5 to 7 nerved, the nerve- 
extending into awns, and the internerves into teeth: palea 2-nerved, 
the nerves extending into short awns: second and third floret with 
