Perennials, 20-80 (rarely to 120 in desert washes) cm, aromatic (rhizomatous). Stems relatively few to relatively numerous, erect, gray-green, simple or widely branched, hairy. Leaves cauline, uniformly gray-green, green, or white, or bicolor (white and green); blades linear to broadly elliptic, 1.5-11 × 0.5-4 cm, entire or lobed to relatively deeply pinnatifid, faces hairy. Heads (erect to nodding, peduncles 0 or 2-5 mm) in congested to open (widely branched) arrays. Involucres campanulate or turbinate, (1-)2-4(-5) × 2-5(-8) mm. Phyllaries (gray-green), lanceolate to ovate or obovate (margins narrowly hyaline), densely tomentose. Florets: pistillate 5-12; bisexual 6-45; corollas yellow, sometimes red-tinged, 1.5-2.8 mm, glabrous. Cypselae ellipsoid ca. 0.5 mm, (obscurely nerved) glabrous. 2n = 18, 36, 54.
Rhizomatous perennial 3-10 dm, simple to the infl, the stem ±white-tomentose at least above; lvs lanceolate or lance-elliptic, 3-10 cm, entire or irregularly toothed to coarsely few-lobed or deeply parted, the undivided portion to 1(-1.5) cm wide, persistently white- tomentose on both sides or becoming glabrous above; invol 2.5-3.5 mm; disk-cors 1.9-2.8 mm; 2n=18, 36. July-Oct. Prairies, dry ground, and waste places. A widespread, variable sp. of w. U.S. and n. Mex., native e. as far as Ill., and occasionally intr. eastward. Most of our plants are var. ludoviciana, with entire to coarsely few-lobed lvs and a mostly compact and elongate infl. (A. gnaphalodes, the form with the lvs persistently tomentose above; A. herriotii; A. pabularis) Var. mexicana (Willd.) Fernald, with many of the lvs deeply parted and with a strong tendency toward a more diffuse, often leafy infl, is chiefly southwestern, occasionally reaching our range as an introduction. (A. mexicana) Other vars. occur westward.
Gleason, Henry A. & Cronquist, Arthur J. 1991. Manual of vascular plants of northeastern United States and adjacent Canada. lxxv + 910 pp.