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Plains Bristlegrass
Large-spike Bristlegrass

Setaria macrostachya
Setaria vulpiseta

Setaria macrostachya photo © by Michael Plagens

Photographed in Rackensack Canyon, Maricopa Co., Arizona. Aug 3, 2008.

PERENNIAL: Robust perennial grass reaching close to 1½ meters in height with good soil and moisture. Warm season growth and flowering.

LEAVES: Leaves are about a cm wide and can range from 8 to 25 cm long.

RANGE: Fairly common in upland Sonoran Desert in Arizona ranging eastward through Texas and the Great Plains. An important range grass.

FRUIT: There is a prominent, slightly twisted bristle below each spikelet giving the whole spike a bristly appearance. There are several closely related species distinguished by finer characteristics of the spikes, lemmas and glumes.

FLOWERS: The spikelets are short and presented in a dense spike 10 cm or so long. Flowering begins after start of summer rains.


spike inflorescence of Setaria macrostachya photo © by Mike Plagens Setaria macrostachya and S. vulpiseta have been treated as distinct species by most authors since they were first described more than 180 years ago. In three recent publications, however, S. macrostachya was listed as a synonym of S. vulpiseta. The present study, which included the examination of some 350 herbarium specimens, has convinced us that these two species are as distinct as many others in the genus, and should continue to be recognized as separate taxa. Toolin & Reeder (2000) Systematic Botany, Vol. 25, No. 1.

Poaceae -- Grass Family

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Copyright Michael J. Plagens, 1999-2009