Culms (5)10-50(75) cm, weak, slender, solitary or with several shoots,
sometimes sparingly branched above the base; internodes usually longer
than the sheaths. Sheaths often purplish; ligules 1.5-5 mm, acute
to truncate, erose, margins decurrent; blades usually 4-12 cm long, 0.3-4
mm wide, flat or convolute when dry. Panicles 3-15(20) cm long, 0.4-1.5(3)
cm wide, contracted, somewhat interrupted below; branches erect to ascending,
most spikelet-bearing to within 2 mm of the base; pedicels 0.5-2 mm. Spikelets
2-2.8 mm, green or purplish; florets 1; rachilla extensions 0.2-0.6
mm. Lower glumes 1-2.2 mm; upper glumes 2-2.5(2.8) mm; lemmas
1.5-2.5 mm, slightly involute, awned, awns 4-10(16) mm; anthers 0.3-0.5
mm, often purplish-brown. Caryopses 1-1.5 mm. 2n = 14, 28.
Apera interrupta grows as a weed in lawns, grain fields (especially winter
wheat), sandy open ground, and roadsides. Introduced from Europe, it now grows
from British Columbia south to Arizona and New Mexico, as well as in Ontario and
a few scattered locations in the eastern part of the Flora region.