Ptilostemon Cass.
Perennial herbs or shrubs, rarely annual or biennial. Stems winged or not. Hairs cobwebby or scabrid. Lvs alternate, sessile, entire or pinnatifid or pinnatisect; lobes and teeth spine-tipped. Capitula homogamous, ovoid, solitary or in corymbs or clusters. Involucral bracts in several series, narrowly deltoid to linear, often with lateral spines, glabrescent or with cobwebby hairs, at least the outer bracts spine-tipped, the outermost recurved or spreading. Receptacle convex; scales numerous, setaceous. Florets all tubular, usually all ⚥, but marginal florets sometimes ♂; corolla glabrous, 5-lobed, usually purple, rarely white. Anthers acute at apex, with lacerate basal appendages 2-4 mm long; filaments bearded. Style branches linear, erect, appressed or diverging slightly at apex. Achenes obovoid, weakly flattened, glabrous, smooth; achene insertion basal; pappus hairs in several rows, soft, silvery, plumose, united at base into a ring, often reduced in marginal florets.
14 spp., Mediterranean. Naturalised sp. 1.
The genus was dealt with in detail by Greuter, W., Boissiera 22 : 1-215 (1973), who also explained its separation from Cirsium.
