2n = c. 96, 100

Erect or straggling annual or short-lived perennial herb. Mid cauline lvs usually almost glabrous, sometimes with scattered short hairs, apetiolate, elliptic or oblong, usually pinnately lobed with the oblong to ovate segments irregularly serrate or dentate, usually amplexicaul and deeply 2-4-fid at base, (35)-60-170 × (8)-15-60 mm. Uppermost lvs and those of depauperate plants smaller, sometimes narrow-elliptic and not deeply lobed but irregularly dentate or serrate. Supplementary bracts 3-7, 1-2 mm long. Involucral bracts (7)-8 -(9), glabrous, 5-7-(8) mm long. Ray florets 0. Disc yellow, 1-2 mm diam. Achenes subcylindric, narrowed to and slightly constricted below apex, usually with 2-3 rows of hairs in narrow grooves between broad ribs, rarely ± evenly hairy, 2.5-2.8 mm long.