Erect, annual or short-lived perennial herb, up to c. 2 m tall. Stems usually glabrous or with a few fine scattered hairs, sometimes sparsely to densely setose (especially above), branched or not from base. Lower and mid cauline lvs usually sparsely hairy, especially below, sometimes glabrous or moderately hairy, apetiolate, 1-pinnatifid with the linear to lanceolate or sometimes broader segments entire or irregularly toothed to again pinnatifid, ovate to elliptic, acute to acuminate at apex, amplexicaul and usually deeply and evenly 3-fid at base, 5-13-(20) × 2-8 cm; venation pinnate. Uppermost cauline lvs smaller, often 1-pinnatisect with entire segments. Capitula in loose panicles. Supplementary bracts 3-4-(7), lanceolate, 1-3 mm long. Involucral bracts 8-13, linear, glabrous, 5-7 mm long. Ray florets 0. Disc greenish yellow, c. 2 mm diam. Achenes subcylindric, only slightly narrowed to and slightly constricted below apex, with 1 row of hairs on or beside ribs or 2-3 rows between, 1.8-2.3 mm long; pappus 5-7 mm long.