Single-awn aristida is a rather unusual member of the three-awn 

 genus because the two lateral awns are very short or entirely lack- 

 ing; hence the English name, single-awn aristida. The generic 

 name comes from the Latin arista, a beard or awn, and refers to the 

 bearded seeds of all members of this genus. This species ranges 

 from western Texas through most of New Mexico, southern Arizona 

 and into Mexico. It has also been reported from San Diego, Calif. 1 

 It grows on the dry mesas, plains, and foothills in open grassland, 

 desert shrub and oak woodland types on rocky, gravelly, or especially, 

 on sandy soils. This grass occasionally is locally abundant but is 

 usually scattered, and frequently grows in association with poverty 

 three-awn (A. divaricata), blue grama (Boutelouw gracilis), galleta 

 (Hilaria jame&li), dropseeds (Sporobolus spp.), mesquites (Prosopis 

 spp.), and scrub live oak (Quercus turbindlal). 



Single-awn aristida is one of the earliest grasses to green up in 

 the spring and, when moisture is adequate, produces considerable 

 early green forage, which is grazed readily by all classes of live- 

 stock. However, the main growing season of this grass comes with 

 the advent of summer rains; while green, it is usually rated good 

 in palatability. Its palatability decreases as the plant reaches ma- 

 turity, and becomes very low after the foliage dries and the awns 

 develop. On a seasonlong basis, it is commonly ranked as fairly 

 good forage. Although the awned seeds of this species are not as 

 troublesome (the awn being single) as those of most three-awn 

 grasses, they are, nevertheless, avoided by grazing animals. 



Single-awn aristida is a perennial bunch grass, commonly from 1 

 to 2 feet tall, with an upright, loosely flowered, often purplish 

 panicle. Its single awn readily distinguishes this plant from other 

 species of Aristida. It is frequently mistaken for a needlegrass 

 (Stipa) because its awns are apparently single and somewhat twisted 

 at the base, like those of the needlegrasses. Upon careful examina- 

 tion, however, the two often very short, lateral branches of the awn 

 are discernible on at least a few of the seeds, a feature which dis- 

 tinguishes it at once from the needlegrasses. 



1 JepSOn, W. L. A MANUAL OF THE FLOWERING PLANTS OF CALIFORNIA. 1,238 pp., illus. 



Berkeley, Calif. [1925.] 



