Erect, annual, odorous herb; stem branched, grooved, covered with soft, glandular hairs; leaves alternate, pinnatisect, sessile, amplexicaul at base, toothed, covered with soft hairs; heads heterogamous, small, few in peduncled, terminal, corymbose panicles; involucres hemispheric, bracts 2-seriate, lanceolate, acute, margins scarious; receptacle with a constructed base, elevated, top concave, naked; florets not rayed; outer florets longer, tubular, many seriate, female, fertile, filiform, 2-toothed; inner florets bisexual, usually sterile, tubular, 5-fid; anther base truncate; style exserted beyond; achenes minute, oblong, smooth; pappus absent.