G16 

 THREE-AWNS 



Ari'stida spp. 



Three-awns, also commonly called needlegrasses, wiregrasses, and 

 poverty grasses, constitute a large genus of the redtop tribe (Agros- 

 tideae) and are widely distributed throughout the Western States, 

 being especially well represented in the Southwest. They grow 

 chiefly on dry sandy soils and are common grasses on semidesert 

 areas, on plains, and at lower elevations in the mountains. 



Three-awns vary greatly in forage value in the different regions 

 of the West. When mixed with the more palatable grasses, such as 

 bluegrasses and fescues, they are usually ranked low even while 

 green. In the Southwest they are often considered good spring 

 and summer forage while green, before the seeds mature. Some 

 species start growth early in the spring before most other grasses 

 and are sometimes valuable as early forage. Some of the south- 

 western three-awns have two growing seasons: One in the spring, 

 if moisture and other weather conditions are favorable, and another 

 in the summer with the advent of summer rains. Under such con- 

 ditions considerable green palatable forage is produced. The small 

 annuals and a few perennial species produce but little leafage and 

 are poor or worthless as forage. A large number of the perennial 

 species, however, are leafy and produce considerable forage; such 

 leafy perennials are more valuable range plants, particularly on 

 spring ranges, than some observers, prejudiced by the prickly beards 

 (awns) and wiry stems of three-awns, are willing to admit. Three- 

 awns mature in summer or fall depending upon the time the summer 

 rains begin, after which time they are of little value as forage. The 

 leaves dry up and are unpalatable and the troublesome seeds (fruits) 

 are avoided by grazing animals. 



Three-awns are relatively short-lived and depend upon seed for 

 reproduction. The seeds are well adapted for dissemination and 

 in general the plants reproduce well. These grasses sometimes indi- 

 cate, on areas where they are abundant, that the site is too poor for 

 the growth of more desirable species, or they may be an indicator 

 of range depletion or other disturbances. 



A characteristic three-branched beard at the tip of the seed is 

 the most outstanding feature by which the three-awns may be 

 distinguished. The two lateral branches of the awn may be small 

 (very small or absent in A. orcwbtiana) . The seed is hard, slender, 

 and cyindrical with a sharp-pointed base covered with short, rather 

 stiff hair. These barbed seeds often trouble grazing animals by 

 working into their eyes, nostrils, and ears, and sometimes causing 

 sore mouth. The individual flower groups (spikelets) are one- 

 flowered (i. e.. each seed or flower is borne singly) and the flowering 

 head (panicle) is usually narrow but open and sometimes spreading. 

 The two empty bracts (glumes) at the base of the spikelet are nar- 

 row and remain attached to the stem (pedicel) after the floret, or 

 seed, has fallen. 



