Annual, biennial or perennial (short-lived), often aromatic, herbs or subshrubs. Stems conspicuously winged from decurrent leaf bases. Leaves alternate, sessile, decurrent; indumentum of uniseriate, multicellular hairs, and/or glandular hairs sometimes present. Capitulescences in terminal clusters, globose, ellipsoid, cylindrical or spiciform; peduncles present or absent. Capitula cylindrical, with involucral bracts in 2(–6 outside Australia) series; the outer bracts persistent, lanate-hairy and sometimes glandular-hairy, all similar in size; the inner bracts caducous, glabrous or with minute sessile glands, outer whorls shorter and broader. Receptacle epaleate, glabrous. Outer florets female, numerous, filiform, pink to purple, fertile; corolla three-lobed; style bifid; achenes narrowly-ellipsoid to obovoid, with a conspicuous white ring-shaped carpopodium; twin hairs antrorse, appressed; pappus in 1 row (–2 outside Australia) of barbellate capillary bristles, connate at base, persistent. Disc floret hermaphrodite, functionally male, abortive, solitary or rarely 2(–15 outside Australia), tubular, filiform, pink to purple; corolla 5-lobed; style bifid; achenes pale.
A genus of c. 26 species in North and South America, Asia, Malesia, Melanesia and Australia; 13 species in Australia (all native).
