5. Setaria verticillata (L.) P. Beauv. (bristly foxtail, bur bristlegrass)

Pl. 175 a, b; Map 706

Plants annual, with soft bases, without rhizomes. Flowering stems 25–100 cm long, sometimes slightly flattened, glabrous. Leaf sheaths somewhat keeled, hairy along the margins toward the tip and glabrous or roughened on the surface, the ligule 0.7–2.2 mm long. Leaf blades 6–30 cm long, 5–15 mm wide, flat, roughened on both surfaces, often also with sparse, longer hairs on the upper surface. Inflorescences 5–15 cm long, erect, the short branches reduced to clusters of spikelets toward the usually tapered tip and slightly elongate toward the base, the branches in definite whorls and the lower ones usually appearing more or less distinct, the main axis roughened with short, stiff hairs, the spikelets subtended by 1 or 2 green, yellow, or purple bristles, these 4–7 mm long. Spikelets 1.8–2.2 mm long, disarticulating below the glumes. Lower glume 0.8–1.2 mm long. Upper glume 1.6–2.2 mm long. Lowermost floret usually sterile, 1.8–2.2 mm long. Fertile floret with the lemma 1.6–2.1 mm long, with noticeable, fine cross‑wrinkles on the surface. Anthers 0.5–0.9 mm long. 2n=18, 36, 54. June–October.

Introduced, scattered, mostly in counties adjacent to the Missouri River (native of Europe; introduced and weedy nearly worldwide). Roadsides, railroads, gardens, and open, disturbed areas.