Plants perennial. Culms 20-100 cm. Sheaths smooth to scab¬ridulous; ligules 1-3(4) mm, rounded to broadly acute, erose; blades 13-17 cm long, 5-7 mm wide, scabrous. Panicles 8-15 cm, lobed or interrupted, usually purplish; pedicels absent or vestigial; stipes 0.3-0.5 mm. Glumes 1.5-3 mm, smooth to echinate, margins ciliate, apices acute to truncate, unlobed or lobed, lobes to 0.1 mm, awned, awns (3)4-6 mm, flexuous; lemmas 1-1.3 mm, awned, awns 2-3.5 mm, flexuous; paleas from shorter than to subequal to the lemmas; anthers 0.3-0.5 mm. 2n = unknown.
Calif., Ariz., Wash., Nev.
Polypogon australis is native to South America. It has become established in western North America, where it grows alongside ditches and streams. The records from Washington and Oregon are from ballast dumps; it is not known from recent collections in those states.