Plains Bristlegrass (Setaria macrostachya)
Main Sources: Gould, Frank, 1951, Grasses of the Southwestern United States, Tucson: University of Arizona Press; Shreve, Forrest & Ira Wiggins, 1964, Vegetation and Flora of the Sonoran Desert, Vol. 1, Palo Alto: Stanford University Press; Kearney, Thomas & Robert Peebles, et al, 1960, Arizona Flora, Berkeley: University of California Press; McClaran, Mitchel & Thomas Van Devender, 1995, The Desert Grassland, Tucson: University of Arizona Press; van Devender, Thomas & Mark Dimmitt, "Desert Grasses", in Phillips, Steven& Patricia Comus, eds., 2000, A Natural History of the Sonoran Desert, pp. 265-80, Arizona-Sonora Desert Museum Press, Tucson; Ruyle, George & Deborah Young, eds., 1997, Arizona Range Grasses, Tucson, University of Arizona College of Agriculture; USDA Conservation Districts of Southeastern Arizona,, n.d., Grasses of Southeastern Arizona. Washington, D.C.
A warm season, perennial bunchgrass, Plains Bristlegrass is bright green during the growing season, with seed stems as high as 3 feet. Leaves are thin, up to 16" long, and somewhat hairy. The inflorescence (below left) is contracted -- spikelike and narrow, up to 10" long with plump seeds and stiff bristly hairs (see details, photos far below).
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(Click on each of the images below to enlarge)
Bristlegrasses are widely distributed in temperate and tropical regions of the world, but of the 13 species known for the United States, Plains Bristlegrass is the only important native forage grass. We find this grass mainly in our larger, silty washes and on nearby slopes, often the north-facing side. It is greatly prized by wildlife as well as cows, but is quickly damaged by excessive grazing.