1. Crypsis schoenoides (L.) Lam.

Pl. 144 a, b; Map 585

Heleochloa schoenoides (L.) Host

Plants annual, forming tufts or loose mats. Flowering stems 5–40 cm long, spreading, glabrous, the nodes darkened. Leaf sheaths glabrous, the ligule a line or band of hairs 0.2–1.0 mm long. Leaf blades 1–8 cm long, 1–3 mm wide, flat or with loosely inrolled margins, glabrous or hairy. Inflorescences short, dense, spikelike panicles 1–4 cm long, 6–10 mm wide, partially enclosed in the subtending leaf sheath, oblong in outline, the branches very short and inconspicuous. Spikelets with 1 floret, strongly flattened laterally, disarticulating below the glumes. Lower glume 1.2–2.0 mm long, narrowly lanceolate, sharply pointed at the tip, 1‑nerved, strongly keeled, short‑hairy along the keel. Upper glume 1.4–2.4 mm long, lanceolate, sharply pointed at the tip, 1‑nerved, strongly keeled, short‑hairy along the keel. Lemma 1.4–2.4 mm long, sharply pointed at the tip, strongly 1‑nerved, awnless, strongly keeled, glabrous (including the base). Palea slightly shorter than the lemma. Stamens 3, the anthers 0.7–1.0 mm long. Fruits 1.0–1.5 mm long, elliptic‑obovate in outline, somewhat flattened, the style base persisting as a short point at the tip, tan, the outer coat shed easily when moistened. 2n=32, 36. July–September.

Introduced, Franklin and St. Louis Counties (native of Europe, Africa, introduced sporadically in the northern U.S. south to Delaware, Missouri, and California). Pastures, roadsides, railroads, and open, disturbed areas.

Crypsis is similar to Sporobolus in its spikelet morphology but differs from that genus in its prostrate, annual habit and its dense, short, spikelike inflorescences. The spikelets of C. schoenoides also are more strongly flattened than those of any Sporobolus species in the state.