Annual or perennial herbs. Lvs alternate, simple, entire or toothed. Capitula solitary. Involucral bracts in 3-5 rows, imbricate, with erect lamina, the outer usually herbaceous, the inner membranous. Receptacle flat or slightly convex; scales O. Outer florets ♀, ligulate; ligules yellow. Inner florets ☿, tubular. Achenes all similar, slightly 4-angled, abruptly constricted below apex; pappus hairs in 1 row, narrow at apex.