Upright, diffusely branched, with hairy gray coating. Leaves 4–8 in., pinnately cut into deep lobes; upper leaves smaller. Flower heads numerous. Narrow bell-shaped to oval cup of pale yellow-green bracts are fringed like a comb and end with slender sharp spines turned outward. White disk flowers (occasionally lavender or pink), equally sized, elongate to create petal-like fringe. Grows in many steppe soils. Along with spotted knapweed, C. biebersteinii, and yellow starthistle, C. solstitialis, this aggressive invasive weed heavily dominates range lands, largely reducing livestock and wildlife forage because of the lack of palpability.
- Rarity: Common
- Flowering Time: All Summer
- Life Cycle: Annual, Perennial
- Height: 8--32 inches
- Habitat: East-Side Forest, Shrub-Steppe, Disturbed, Meadow
- Found In: Olympic Np, Mt. Rainier Np, Crater Lake Np, Wallowas, Steens, Siskiyous, East Gorge, N Cascades Np
- Native: No