Plants 10-70 cm. Leaves basal and cauline; blades 1-nerved, linear to narrowly oblanceolate or lanceolate, 2-8 cm × 2-10 mm, distal cauline smaller, linear, faces bicolor, abaxial gray, silvery sericeous, adaxial green, glabrescent. Heads (20-90) in loose, spiciform (leafy-bracteate, interrupted) arrays (4-35 cm, occupying ¹/3-⁵/6 plant heights, simple or branched at bases, primary axes mostly visible). Involucres campanulo-turbinate, 5-6.5 mm. Phyllaries some or all with conspicuous dark brown spot distal to middle. Cypselae cylindric to fusiform, minutely strigose; pappus bristles basally connate, falling together. 2n = 56.

Flowering Jul-Sep(-Oct). Open woods, boggy woods, rocky slopes, clearings, fields, borders of woods, roadsides, muddy banks, disturbed sites; 10-500 m; St. Pierre and Miquelon; B.C., N.B., Nfld. and Labr. (Nfld.), N.S., Ont., P.E.I., Que.; Maine, Mich., N.H., N.Y., Pa., Vt., Wis.; Europe; Asia (Caucasus, Iran, Siberia).

The circumboreal Omalotheca sylvatica may have been introduced from Eurasia (Frére Marie-Victorin 1995). Omalotheca alpigena (K. Koch) Holub and O. caucasica (Sommier & Levier) S. K. Cherepanov were treated as synonyms of O. sylvatica by A. J. C. Grierson (1975); they have been recognized as distinct species in other treatments.