Annual or occasionally perennial herbs. Lvs opposite at least below, often alternate above, simple, usually entire, sometimes denticulate at base. Capitula subsessile or pedunculate, in loose to congested corymbs or racemes. Involucral bracts in 1 row, foliaceous. Receptacle flat or convex, with a single ring of scales between ray and disc florets and these often united, otherwise glabrous or hairy. Outer florets ♀, ligulate, usually yellow. Inner florets ☿ or functionally ♂, tubular. Achenes all similar, usually laterally compressed, narrowed to base, ± 3-angled and sometimes ribbed; pappus usually 0, sometimes a small corona or of scales.