9. Muhlenbergia schreberi J.F. Gmel. (nimblewill)
Pl. 151 d,
e; Map 619
Plants without rhizomes, forming tufts, clumps, or colonies.
Flowering stems 15–60(–80) cm long, erect from usually spreading bases, dull,
minutely hairy below the nodes, not bulbous‑thickened at the base but
frequently rooting at the lower nodes. Leaf sheaths glabrous or roughened and
sometimes with a few long hairs at the tip of the margins, keeled, the ligule
0.1–0.4 mm long. Leaf blades 1–10 cm long, 1–4 mm wide, flat, glabrous or
usually sparsely long‑hairy at the base. Inflorescences dense, spikelike,
mostly terminal panicles 4–20 cm long, linear in outline, the base noticeably
stalked and not enclosed by the subtending leaf sheath, the branches short,
appressed to the main axis or nearly so. Spikelets 1.8–2.8 mm long (excluding
the awns), short‑stalked, the stalks shorter than to less than 2 times as
long as the spikelets. Glumes reduced, 0.1–0.4 mm long, much shorter than the
floret, lanceolate to oblong‑ovate, only slightly overlapping at the
base, rounded to bluntly pointed at the tip, nerveless, awnless. Lemma with the
body 1.8–2.8 mm long, lanceolate to narrowly ovate, the tip sharply pointed, with
an awn 1.5–5.0 mm long, with a tuft of short hairs at the base, otherwise
roughened along the midnerve. Anthers 0.1–0.5 mm long. Fruits 1.0–1.4 mm long.
2n=40 July–November.
Scattered to common nearly throughout the state (eastern U.S. west to Minnesota, Nebraska, and Texas; Mexico). Bottomland forests, mesic to less commonly dry
upland forests, moist depressions of upland prairies, ledges of bluffs, and
banks of streams, spring branches, and rivers; also pastures, old fields,
lawns, roadsides, and moist, disturbed areas.
This is perhaps the most disturbance‑adapted species
of Muhlenbergia in Missouri, occurring in a wide variety of natural and
disturbed habitats without apparent regard to soil type or substrate. Unusual
plants from Barry and Jackson Counties with glumes 1–2 mm long, very short
lemma awns, and sometimes short rhizomes were treated by Steyermark (1963) as M.
schreberi var. curtisetosa (Scribn.) Steyerm. & C.L. Kucera.
Pohl (1969) noted that such specimens occur sporadically nearly throughout the
range of M. schreberi and as far as he could tell produced abortive
pollen. He called these plants M. ¥curtisetosa (Scribn.) Bush and treated them as a series of sterile
hybrids between M. schreberi and several rhizomatous species. Pohl
(1969) analyzed the few specimens from Missouri and concluded that they
represented different possible parental combinations, with M. bushii, M.
frondosa, and M. tenuiflora possibly hybridizing with M.
schreberi.