Plant Form: Perennial herb, spreading with rhizomes.
Size: Up to 100 cm tall.
Stem: Green, smooth, sometimes hairy, with white spines.
Leaves: Dark green above, white below, spiny, lobed, 1-7 cm long.
Flowers: Purple, narrow, in heads with 8-15 mm diameter bracts in several series, with short spines at tips, sometimes hairy or cobwebby.
Fruit and Seeds: 3 mm long, smooth, with parachuting hairs 20-25 mm long.
Habitat: Roadsides, pasture and cropping land.
Distinguishing Features: Flowerheads narrowly cylindric and in large clusters, compard to wide, solitary or in small clusters in Spear thistle (Cirsium vulgare).
Impacts: Decreases agricultural productivity by competing with crop species, can cause injury if grazed, and is a potential host for pests and diseases.