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Plant Form: Perennial herb, spreading with rhizomes.
Size: Up to 1 m 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, grouped in large clusters.
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, compared to wide, solitary or in small clusters in Spear thistle (Cirsium vulgare).