Nimblewill

Muhlenbergia schreberi Gmel. Syst. Veg. 2: 171. 1791
Muhlenbergia diffusa Willd. Sp. PI. 1: 320. 1797. (Type from North America.)
Dilepyrum minulillorum Michx. Fl. Bor. Am. 1: 40. 1803. (Type from Kentucky and Illinois).
Listed as Dylepyrum miiUiflorum by Beauv. Agrost. 160. 1812. Cynodon diffusus Raspail, Ann. Sci. Nat. 5: 303. 1825. (Based on "Muhlenbergia Schr." [error
for Willd.].) Muhlenbergia Botleri Foum. Mex. PI. Gram. 85. 1886. (Type from Orizaba, Mexico.) Muhlenbergia minutiflorum Hitchc. Trans. Kansas Acad. 14: 140. 1896. (Based on Dilepyrum
minuiiflorum Michx.)
Perennial; culms slender, glabrous, branching, spreading and decumbent at base, usually rooting at the lower nodes, but not forming definite creeping rhizomes, the flowering branches ascending, rather lax, 10-30 cm. long; sheaths somewhat keeled, glabrous or slightly scabrous, more or less pilose at the throat, shorter or sometimes a little longer than the internodes; ligule a ciliate membrane about 1 mm. long ; blades flat, scabrous on the margins and more or less so on both surfaces, pilose in the vicinity of the ligule, linear, rounded at the base, usually less than 5 cm. long, 2-4 mm. wide; panicles terminal and axillary, slender, loosely flowered, lax, nodding, 5-15 cm. long, sometimes as much as 30 cm., the scabrous branches appressed or ascending, the lower often distant, the lateral pedicels scabrous, 0.5 mm. long; glumes minute, the first often obsolete, the second rounded, 0. 1-0.2 mm. long; lemma narrow, acuminate, somewhat pubescent around the base, the body about 2 mm. long, the slender awn 2-3 cm. long.
Type LOCALITY: Pennsylvania.
Distribctio.n: Damp shady places. New Hampshire to Wisconsin and eastern Nebraska, and southward to Florida, Texas, and eracruz.
Note 1 : In spring and early summer the culms are short and erect with spreading blades, the plants being very different in appearance from the flowering phase of autumn.
Note 2: Muhlenbergia was based on the species described by Schreber (Gen. 1: 44. 1789) under Muhlenbergia with no specific name.
Muhlenbergia Schreberi var. palustris (Scribn.) Scribn. Rhodora 9: 17. 1907. Muhlenbergia paluslris Scribn. Bull. U. S. Dep. Agr. Agrost. 11; 47. 1898. Glumes developed, as much as 1 mm. long. Tyte locality: District of Columbia . Distribution: Known only from Washington, D. C. Illustrations: Bull. U. S. Dep. Agr. 772:/. S2; Bull. U. S. Dep. Agr. Agrost. 7:/. 99 (as M. diffusa).

Perennials, Terrestrial, not aquatic, Stems trailing, spreading or prostrate, Stems nodes swollen or brittle, Stems geniculate, decumbent, or lax, sometimes rooting at nodes, Stems caespitose, tufted, or clustered, Stems terete, round in cross section, or polygonal, Stems branching above base or distally at nodes, Stem internodes hollow, Stems with inflorescence less than 1 m tall, Stems, culms, or scapes exceeding basal leaves, Leaves mostly cauline, Leaves conspicuously 2-ranked, distichous, Leaves sheathing at base, Leaf sheath mostly open, or loose, Leaf sheath smooth, glabrous, Leaf sheath and blade differentiated, Leaf blades linear, Leaf blades 2-10 mm wide, Leaf blades mostly flat, Leaf blades mostly glabrous, Ligule present, Ligule an unfringed eciliate membrane, Inflorescence terminal, Inflorescence a contracted panicle, narrowly paniculate, branches appressed or ascending, Inflorescence solitary, with 1 spike, fascicle, glomerule, head, or cluster per stem or culm, Inflorescence branches more than 10 to numerous, Flowers bisexual, Spikelets pedicellate, Spikelets laterally compressed, Spikelet less than 3 mm wide, Spikelets with 1 fertile floret, Spikelets solitary at rachis nodes, Spikelets all alike and fertille, Spikelets bis exual, Spikelets disarticulating above the glumes, glumes persistent, Spikelets disarticulating beneath or between the florets, Rachilla or pedicel glabrous, Glumes present, empty bracts, Glumes minute, much smaller than lemmas, Glumes 2 clearly present, Glumes equal or subequal, Glumes shorter than adjacent lemma, Glumes awned, awn 1-5 mm or longer, Glumes 1 nerved, Lemmas thin, chartaceous, hyaline, cartilaginous, or membranous, Lemma similar in texture to glumes, Lemma 3 nerved, Lemma glabrous, Lemma apex acute or acuminate, Lemma distinctly awned, more than 2-3 mm, Lemma with 1 awn, Lemma awn 1-2 cm long, Lemma awn 2-4 cm long or longer, Lemma awned from tip, Lemma awns straight or curved to base, Lemma margins thin, lying flat, Lemma straight, Callus or base of lemma evidently hairy, Callus hairs shorter than lemma, Palea present, well developed, Palea membranous, hyaline, Palea about equal to lemma, Palea 2 nerved or 2 keeled, Stamens 3, Styles 2-fid, deeply 2-branched , Stigmas 2, Fruit - caryopsis, Caryopsis ellipsoid, longitudinally grooved, hilum long-linear.

Muhlenbergia schreberi, the nimblewill, is a grass species in the family Poaceae native to North America.