Plants perennial; not cespitose, rhizomatous, rhizomes to 40 cm. Culms 20-100(150) cm, usually decumbent at the base; lower internodes glabrous or sparsely pubescent. Sheaths glabrous or hirsute; ligules 1-5 mm, obtuse, erose; blades 2-20 cm long, 3-10 mm wide, pubescent. Panicles 4-20(22) cm long, to 3 cm wide; branches puberulent or ciliate; pedicels to 5 mm long, pilose, hairs to 0.3 mm. Spikelets 4-6(7) mm; rachillas hairy. Glumes exceeding and enclosing the florets, subequal, nearly the same width, ovate, membranous, whitish-green when young, straw-colored with age, veins ciliate, often purple, intercostal regions scabrous or glabrous, apices acuminate or acute, unawned; calluses densely to sparsely hirsute; lemmas 2-2.5 mm, glabrous, acute; upper lemmas bifid, awned above midlength, awns 3-5 mm, scabrous, straight or geniculate at maturity; anthers about 2 mm. 2n = 28 (35, 42, 49).

Holcus mollis grows in moist soil and disturbed sites, including lawns and damp pastures. It is a European introduction that has persisted in the Flora region, becoming a problematic weed in ungrazed pastures, prairie remnants, and oak savannahs in portions of the Pacific Northwest. It is also sold as an ornamental. There are two subspecies: Holcus mollis L. subsp. mollis (stems not thickened and tuberous at the base; panicles lax, brownish or purplish) and H. mollis subsp. reuteri (Boiss.) Malag. (stems thickened and tuberous at the base; panicles narrow, whitish). North American introductions belong to subsp. mollis.