Spike redtop, so named because of its spikelike panicle, is also 

 known as purple redtop and western redtop. This perennial bunch 

 grass is one of the commonest and most valuable western species of 

 redtop. Because it is exceedingly variable in size and form, this 

 species has been the victim of extensive botanical emasculation and 

 appears in various manuals as A. ampla, A. asperifolia, A, densiflora, 

 A. glomerata, A. grandis, A. inflata, A. microphylla, and A. scouLeri. 

 The present trend among botanists, however, is to include all these 

 under the one species, A. exarata. 



This species is widely distributed in western North America, 

 ranging from Alaska to southern California and Mexico, and east- 

 ward to western Texas, western Nebraska, and Manitoba. Its eleva- 

 tional range extends from about sea level on the Pacific Coast to 

 approximately 10,500 feet in Colorado, Utah, New Mexico, and the 

 southern portion of its range. This grass is a moisture-loving 

 species but it is less exacting in its moisture requirements than some 

 of the other redtops. It typically occurs in meadows, along streams, 

 in moist parks, and in moist, semishaded woodlands and aspen stands. 

 However, it also appears on drier situations, growing on moderately 

 dry soils in association with wheatgrass, sagebrush, needlegrass, and 

 oakbrush. 



Spike redtop often occurs in abundance on the moister portions 

 of the range, being especially common near the California seacoast, 

 where it reaches its best development. In some localities this grass 

 furnishes a large part of the forage. 1 The herbage remains green 

 and succulent until late in the season and is grazed throughout the 

 summer by all classes of livestock. Its forage value varies somewhat 

 in different portions of the West. On the average, the palatability 

 is considered to be good to very good for cattle and horses and from 

 fair to good for sheep. Elk relish the herbage of this plant and deer 

 use it to a slight extent. The period of flowering and seed dissemi- 

 nation varies with the altitudinal and latitudinal range of this plant. 

 Under average conditions the seed ripens between the first week in 

 August and the early part of September. The production of a moder- 

 ate amount of seed having fair viability is characteristic. 2 



This grass varies in size and form according to its habitat, ranging 

 from dwarf plants with small dense panicles in alpine situations to 

 tall robust forms. Dwarf forms are generally awned with delicate 

 prickles on the back of the lemmas. The plant described as A. 

 glomerata is a low seacoast form with a compact panicle and often 

 inflated sheaths; A. vrdcrophyUa has dense, often interrupted panicles 

 and well-developed awns; A. grandis is a robust form up to 60 inches 

 tall with compact panicles and awnless lemmas; and A. ampla, 

 another tall form, has somewhat open panicles and awned lemmas. 

 The form originally described as A. exordia occupies an intermediate 

 position in the range of variation. 



1 Dayton, W. A. SOME OUTSTANDING FORAGE GRASSES OF WESTERN CATTLE RANGES. 

 Producer 9 (10) : [3]-7, illus. 1928. 



a Sampson, A. W. NATIVE AMERICAN FORAGE PLANTS. 435 pp., illus. New iTork. 1924. 



