11. Bromus squarrosus L. (one‑way brome, one‑way chess)

Pl. 137 e, f; Map 566

Plants annual, forming tufts. Flowering stems 20–60 cm long, erect or ascending, mostly glabrous. Leaves 4–6(–8) per stem. Leaf sheaths loosely overlapping toward the base of the stem, hairy (the upper ones often sparsely so), the tip strongly concave (V‑shaped), lacking a well‑defined ring of hairs on the outer surface and without auricles. Leaf blades 3–15 cm long, 1–5 mm wide, hairy, dull on the undersurface. Inflorescences open panicles with several spikelets, sometimes nearly racemose with relatively few spikelets, the branches spreading or drooping at maturity, the stalks of the spikelets mostly slightly longer than the spikelets. Spikelets 20–35 mm long, slightly compressed laterally at maturity, with 11–30 florets. Lower glume 4–7 mm long, elliptic, 3–7‑nerved, glabrous but usually roughened along the nerves. Upper glume 6–9 mm long, broadly elliptic, 5–9‑nerved, glabrous but usually roughened along the nerves. Lemmas 8–11 mm long, broadly elliptic to somewhat elliptic‑obovate, the distance (in lemmas toward the middle of the spikelet) from the midnerve to margin 2.5–3.5 mm at the widest point, rounded on the back, the margins not or only slightly inrolled at maturity, with a conspicuous, broad, whitened band, 7‑ or 9‑nerved, glabrous but usually roughened along the nerves, the apical teeth 2–3 mm long, the awn (1.5–)5.0–12.0 mm long, mostly curved, twisted, or abruptly bent outward at maturity. Paleas shorter than the lemmas. Anthers 1.0–1.3 mm long. Fruits 5–6 mm long, circular in cross‑section to somewhat flattened or slightly V‑shaped, the longitudinal groove narrow and shallow. 2n=14, 28. June–July.

Introduced, known only from New Madrid County and St. Louis (native of Europe and Asia, naturalized sporadically in the northwestern, central, and northeastern U.S. and adjacent Canada). Railroads and pastures.

Depauperate or juvenile plants of this species are very difficult to separate from B. japonicus or B. commutatus.

Missouri was included in the range of Bromus briziformis Fisch. & C.A. Mey., rattlesnake chess, by Pavlick (1995), but to date no specimens have been located to document its occurrence in the state. This widely naturalized species should be found in Missouri eventually, as it has been collected in several surrounding states. It differs from B. squarrosus in having the lemmas somewhat inflated and awnless or nearly so.