1. Apera interrupta (L.) P. Beauv. (Italian windgrass)

Pl. 132 c, d; Map 535

Agrostis interrupta L.

Flowering stems 10–45 cm long. Leaf sheaths with the ligule 1.5–4.0 mm long. Leaf blades 1–10 cm long, 1–4 mm wide, the margins usually strongly inrolled. Inflorescences 5–18 cm long, relatively narrow, with strongly ascending branches at maturity. Lower glume 1.7–2.2 mm long. Upper glume 2.0–2.5 mm long. Lemma 1.6–2.2 mm long. Anthers 0.3–0.4 mm long. 2n=14, 28. May–July.

Introduced, uncommon, known thus far only from Boone County and St. Louis (native of Europe, Asia; introduced in the western U.S. sporadically east to Missouri and Massachusetts, also southern Canada). Railroads, lawns, and disturbed, grassy areas.