Distribution: Occurring east of the Cascades crest in Washington; British Columbia to California, east to Michigan and Texas.
Habitat: Dry hillsides and plains at low elevations.
Growth Duration: Biennial, Perennial
Conservation Status: Not of concern
Stout, short-lived perennial from a tap-root, branched above and sometimes below the surface, 3-12 dm. tall, densely, closely, and persistently white-woolly throughout.
Leaves up to 3 dm. long, coarsely toothed to pinnatifid, the lobes ovate or deltoid, usually over 7mm. wide, the margins spiny.
Heads several to numerous at the ends of the branches; involucre 2.5-4 cm. high, its bracts with a glandular-glutinous dorsal ridge, the inner with pointed tips, the others with spine tips 3-5 mm. long; flowers all ligulate, pink-purple, but often so pale as to appear dirty-white.
Achenes 4-7 mm. long, light brown.
PNW Herbaria: Specimen records of Cirsium undulatum in the Consortium of Pacific Northwest Herbaria database.
WA Flora Checklist: Cirsium undulatum checklist entry.
OregonFlora: Cirsium undulatum information.
E-Flora BC: Cirsium undulatum atlas page.
CalPhotos: Cirsium undulatum photos.
USDA Plants: Cirsium undulatum information.