Cirsium

Perennial or rarely annual herbs. Leaves alternate, often decurrent, serrate or pinnately lobed, lobes and teeth spinescent or rarely rigidly ciliate. Capitula discoid, many-flowered, solitary, corymbose or variously clustered. Involucre ovoid or globose; bracts in many rows, spiny or innocuous. Receptacle flat or convex, densely setose. Florets bisexual, fully fertile or female; corolla purple, tube narrowly cylindric below, slightly widened above, deeply 5-lobed. Anthers linear, sagittate, adjacent auricles connate and prolonged into entire or lacerated tail. Style abruptly thickened below branches, often with ring of hairs there; branches, often partly connate, sometimes linear or filiform. Cypselas obovoid-oblong, glabrous, with nearly central, horizontal, basal attachment scar. Pappus of feathery bristles in several rows; connate at base. x = 17 (7, 8, 9, 10, 11, 12, 13, 15) (aneuploids, polyploidy, B-chromosomes).