Annual herbs. Lvs 2-3-pinnatisect, alternate. Capitula in corymbs or often solitary, terminal, pedunculate; involucral bracts in 2-3 rows, with membranous margins. Receptacle conic; scales 0. Outer florets ♀ and ligulate, or ☿ and tubular; ligules white; inner florets ☿, tubular. Achenes usually all similar, terete, mucilaginous when wet; ribs 3-10, strongly developed on inner surface; pappus a small corona or 0.
Annual herbs, erect. Leaves 2-or 3-pinnatisect. Capitula solitary or few, rarely subsessile, radiate or discoid; involucre ±3-seriate, with all or nearly all bracts ±equal in length; receptacle epaleate. Ray florets female, fertile. Disc florets bisexual; corolla 4-or 5-lobed. Achenes ±homomorphic, terete or slightly compressed, with 4 or 5 ribs concentrated adaxially. Pappus present.