GENERA OF GRASSES OF THE UNITED STATES. 
99 
the opposite sides of the spike being imbricate in a row, so that the 
spike appears to be 4-rowed. In 6-rowed barley (H. hexastichon L.) 
Fig. 40. — Bottle-brush grass, Hystriw paiula. Plnnf, x 1 ; spikelet nnd floret, X 3. 
the lateral spikelets form rather distinct roAYs. In 2-rowed barley 
(H. distichon L.) the lateral spikelets are all infertile and reduced. 
