Plants perennial; rhizomatous. Culms 55-140 cm, erect from decumbent bases, glabrous; nodes 3-5. Sheaths glabrous; ligules 3-9 mm, obtuse-erose; blades 5-26 cm long, 8-17 mm wide, flat, glabrous, equably distributed on the culms. Panicles 10-27 cm; branches 1-9 cm, in pairs or fascicles, flexuous, spreading or drooping, scabrous, the spikelets mainly near the ends. Glumes 2.5-5 mm, scabrous, 3-veined, acute to acuminate; lemmas 2.3-3 mm, acute; anthers 1.5-2 mm. 2n = 14, 28.
Milium effusum is widespread in temperate to subarctic regions in the Northern Hemisphere. North American plants belong to M. effusum var. cisatlanticum Fernald, an elegant native grass that grows in woodlands in eastern North America. It differs from M. effusum L. var. effusum, which grows from Europe to Asia and Japan, in having 2-3 panicle branches at most nodes and spikelets 2.5-5 mm long, rather than 4-5 panicle branches at most nodes and spikelets about 3 mm long. A cultivar of M. effusum, 'Aureum', is grown for its yellowish leaves. 2010: Haines raised M. effusum var. cisatlanticum to subspecific rank as Milium effusum subsp. cisatlanticum (Fernald) A. Haines.
Glabrous and glaucous perennial 6-12 dm, erect from a bent base; ligules prominent and pale; main lvs 10-18 mm wide; panicle 1-2 dm; ovoid or pyramidal, the branches in fascicles of 2 or 3, widely spreading and bearing drooping spikelets beyond their middle; glumes scaberulous, ca 3 mm; 2n=14, 28. Rich, moist or dry woods; Que. and N.S. to Ont. and Minn., s. to n. N.J., W.Va., and Ill.; also in Eurasia.
Gleason, Henry A. & Cronquist, Arthur J. 1991. Manual of vascular plants of northeastern United States and adjacent Canada. lxxv + 910 pp.