PRAIRIE THREEAWN, Aristida oligantha
Michx. 1, entire plant showing habit; 2, glumes and floret.
Annual, reproducing by seeds. Roots fibrous. Stems
branched near surface of ground, wiry, 12 to 26 inches (30 to 65 cm) high,
smooth or sometimes slightly rough. Leaves very narrow, flat, smooth,
tapering to fine point. Panicle loose, terminal, each containing
a few short-pediceled, narrow, 1-flowered spikelets. Seeds bear
a triple awn with bristles of nearly equal length. Awns 1 to 3 inches (2.5
to 7.5 cm) long, somewhat spirally curved at base. Found generally
on open, dry, sterile soil, especially overgrazed prairies and abandoned
land that was formerly cultivated. Awns cause irritation in mouth and nostrils
of livestock. Several other species of threeawn grasses are found and can
be recognized as belonging to the genus Aristida from this illustration.