Carduus L.
Annual to perennial herbs. Stems winged. Hairs soft and multicellular, or cobwebby, sometimes papillate. Lvs alternate, sessile or cuneate at base, simple, dentate to pinnatisect; lobes and teeth spine-tipped. Capitula homogamous, cylindric to ovoid, globose, obconic or hemispheric, solitary or in clusters. Involucral bracts in several series, lanceolate to linear, evenly tapered or with a narrow claw and broader limb; hairs papillate, cobwebby, or 0; outer bracts usually spine-tipped. Receptacle flat; scales numerous, setaceous. Florets ⚥, all tubular. Corolla glabrous, 5-lobed, usually purple, rarely pink to white. Anthers acute at apex, with basal appendages 0.5-1.5 mm long; filaments ciliate or papillate. Style branches linear, erect, appressed. Achenes obovoid, weakly flattened, glabrous, smooth; achene insertion basal; pappus hairs in several rows, soft or ± stiff, silvery or sordid, scabrid, united at base into a ring.
Key
100 spp., Europe, Mediterranean, Asia. Naturalised spp. 4.
Carduus is easily distinguished from Cirsium by its scabrid rather than plumose pappus hairs (Fig. 32). However there are no other clear distinctions.