Tap-rooted annual or short-lived perennial herb, glabrous or rarely with a few hairs on upper stem; stems erect, terete, sparingly branched below, 20-200 -(300) cm tall, rarely stems resprouting and somewhat woody after flowering. Mid cauline lvs lanceolate to linear, apetiolate and cuneate, acute, crenulate or remotely serrulate, 35-150 × 3-10-(20) mm; lowermost lvs mostly petiolate, elliptic, cuneate, obtuse; uppermost lvs linear. Infl. a many-headed diffuse panicle. Capitula 2-5 mm diam. Involucral bracts very unequal; inner bracts narrow-oblong to subulate, acute to slightly acuminate, green toward apex and along midrib, purplish at apex and margins, 5-8 mm long; outer bracts not wholly herbaceous, c. 2 mm long. Ray florets numerous; ligules white to pale purple, c. 1-2 mm long. Achenes subcylindric to ellipsoid, compressed, 4-5-ribbed, 1.5-2.2 mm long, with sparse antrorse hairs.