Pl. 155 k, l; Map 632

S. vaginiflorus var. inaequalis Fernald

Plants annual, forming tufts. Flowering stems 15–50(–60) cm long, relatively slender. Leaf sheaths only slightly inflated, appearing 0.8–1.7 mm wide when folded, glabrous or rarely with small tufts of short hairs and/or a few longer, pustular‑based hairs at the tips of the margins and on the surface, the ligule 0.2–0.3 mm long. Leaf blades 1–12 cm long, 0.5–2.0 mm wide, flat or with inrolled margins, roughened, rarely also with sparse, pustular‑based hairs toward the base. Inflorescences terminal and lateral in most of the leaf axils, 1–5 cm long, spikelike panicles, linear in outline, mostly enclosed in the subtending leaf sheaths or the terminal one sometimes somewhat free from the subtending sheath, the branches short, appressed, the lowermost ones alternate. Spikelets 1.9–5.0 mm long, the glumes nearly the same length, usually slightly shorter than the floret. Lower glume 1.8–4.7 mm long, lanceolate to narrowly triangular, sharply pointed at the tip. Upper glume 1.8–4.5 mm long, lanceolate to narrowly triangular, sharply pointed at the tip. Lemma 2.3–5.0 mm long, lanceolate to narrowly triangular, 1‑ or 3‑nerved, the lateral nerves (when present) often faint, tapered to a sharp point at the tip, pale yellow and often irregularly mottled with purple at maturity, pubescent with short, straight, light‑colored hairs appressed to the surface between the nerves. Paleas about as long as or somewhat longer than the lemmas and similarly hairy. Anthers (0.2–)1.4–3.2 mm long. Fruits 1.8–2.1 mm long, elliptic‑obovate, tan to reddish brown. 2n=54. August–November.

Scattered to common nearly throughout the state (eastern U.S. and adjacent Canada west to Minnesota, Texas, and Arizona). Glades, upland prairies, savannas, openings of mesic to dry upland forests, and uncommonly banks of streams and rivers, usually (but not always) on calcareous substrates; also pastures, old fields, roadsides, railroads, and dry, open, disturbed areas.

This species is very variable in the density of the tufts. Robust individuals sometimes have dense rosettes of short, leafy, prostrate vegetative stems and few, longer, erect flowering stems. Other plants consist of a single, erect flowering stem and few basal leaves. Such individuals can be difficult to distinguish from S. ozarkanus.