20. Panicum oligosanthes Schult.

Pl. 166 e, f; Map 681

Dichanthelium oligosanthes (Schult.) Gould

Plants perennial, without rhizomes, forming tufts. Flowering stems 10–70 cm long, erect or spreading, initially unbranched, becoming much‑branched during the summer and autumn, the nodes and internodes glabrous or variously hairy. Foliage in a dense rosette of shorter, somewhat broader leaves at the base and longer, narrower leaves well distributed along the main stems, those of the later branches often appearing as axillary fascicles of even shorter, narrower leaves. Leaf sheaths glabrous or variously hairy, the hairs all similar in length and orientation, at least some of the hairs sometimes with pustular bases, the ligule 1.5–2.0 mm long, an inconspicuous to less commonly conspicuous line or band of hairs sometimes additionally with at least a few hairs to 4.0 mm long. Leaf blades of the main stems 3–14 cm long, 3–12 mm wide, abruptly rounded or truncate at the base, relatively thick and stiff, dull green to olive green, glabrous or variously hairy on the undersurface, some of the hairs sometimes with pustular bases. Inflorescences 4–12 cm long, the earlier ones larger and more open with mostly spreading to loosely ascending branches (later ones sometimes reduced to small clusters of long‑stalked spikelets), the branches mostly rebranched 1 or more times, not spikelike or 1‑sided, the spikelets appearing short‑ to long‑stalked at the tips of the branches. Spikelets 2.7–4.0 mm long, broadly elliptic‑obovate in outline. Lower glume 0.7–1.3 mm long, 1/4–1/3 as long as the spikelet, broadly ovate, bluntly to sharply pointed at the tip, glabrous or sparsely hairy, nerveless or faintly 1–5‑nerved. Upper glume 2.2–3.8 mm long, broadly elliptic‑obovate, rounded or very bluntly pointed at the tip, strongly 5–9‑nerved, glabrous or more commonly hairy. Lowermost floret sterile and with a well‑developed, conspicuous palea, the lemma 2.2–3.8 mm long, broadly elliptic‑obovate, rounded or very bluntly pointed at the tip, strongly 5–9‑nerved, glabrous or more commonly hairy. Fertile floret 2.0–3.2 mm long, elliptic, rounded or bluntly pointed at the tip. Anthers 0.2–1.1 mm long. 2n=18. May–July (vernal), June–September (autumnal).

Common nearly throughout the state (U.S., Canada, Mexico). Bottomland and upland prairies, sand prairies, glades, ledges of bluffs, mesic to dry upland forests, banks of streams, margins of ponds and sinkhole ponds, sloughs; also roadsides, railroads, pastures, fallow fields, old fields, and open, disturbed areas.

This is one of the most common species of subgenus Dichanthelium in Missouri, and Steyermark (1963) noted that it is an important secondary forage grass. It is distinctive in its relatively turgid spikelets with the upper glume and sterile lemma strongly nerved. Two overlapping varieties can be recognized by the following combination of characters.