Perennials, 30-150 cm. Stems (commonly branched in distal ¹ / 4 ) glabrous or densely spreading-hirtellous, not glaucous. Leaves spreading to ascending; blades 3- or 5-nerved, linear to lanceolate, 37-130 × (2.1-)3-12 mm, lengths 7-20 times widths, abruptly to gradually reduced distally, herbaceous to firm-herbaceous, margins scabro-ciliate, apices obtuse to acuminate, faces usually little and obscurely gland-dotted (26-47 dots per mm²), barely viscid (more so on exposed shores), glabrous or densely spreading-hirtellous. Heads glomerulate, usually in flat-topped arrays (1.5-28 cm diam.), 10-28% of plant heights (branches unequal, giving irregular, broken appearance). Involucres broadly campanulate to campanulate, 3-5.3 mm. Phyllaries often ± yellow basally, outer (at least) usually green-tipped, outer ovate, inner oblong, apices obtuse or broadly acute. Ray florets (7-)17-22(-35). Disc florets (3-)5-7(-13); corollas 2.6-3.4 mm. 2n = 18. Flowering Jul-Oct. Open fields, lake shores, and vacant lots; 0-900 m; St. Pierre and Miquelon; Alta., B.C., Man., Nfld. and Labr. (Nfld.), N.W.T., N.S., Ont., P.E.I, Que., Sask.; Ala., Colo., Conn., Del., Ill., Ind., Iowa, Ky., Maine, Md., Mass., Mich., Minn., Miss., Mo., Mont., N.H., N.J., N.Y., N.C., Ohio, Okla., Oreg., Pa., R.I., S.C., S.Dak., Tenn., Vt., Va., Wash., Wis., W.Va., Wyo.; introduced in Europe, Asia. Plants with densely hairy leaves and stems have been called var. nuttallii. Though extremes are distinct, the plants cannot be reliably separated rangewide from typical Euthamia graminifolia. Plants called var. major have been distinguished primarily on the basis of leaf dimensions (lengths 8-11 times widths in var. major versus 11-20 in typical E. graminifolia). Overlap is extensive; no discrete boundaries can be drawn.

Euthamia hirtipes was described as a putative hybrid involving a hairy E. graminifolia and a small-headed E. caroliniana (M. L. Fernald 1946d). It combines broad, hairy leaf blades with few-flowered heads, a condition that is not intermediate between the putative parents. D. J. Sieren and J. F. Merrit (1980) and C. E. Taylor (1975) reviewed the plants. Until evidence can be supplied to the contrary, E. hirtipes should be considered a synonym of E. graminifolia.