Family: Asteraceae
field thistle, pasture thistle, prairie thistle
[Carduus discolor (Muhl. ex Willd.) Nutt., more...]
Aaron Carlson
Derek Anderson
University of Wisconsin - Madison (WIS-VP)
Etymology: discolor = two or different colors.
Plants: Erect perennial, 3-7 ft tall, silvery, widely branching, spiny.
Leaves: Large, firm, spiny, deeply pinnately-divided, underside with a whitish fuzz.
Flowers: Head up to 1 1/2 in wide with pale pink disc flowers, 1 to many heads on a somewhat leafy stalk.
Phenology: Blooms July to October.
Habitat: Dry to moderate moisture; prairies and fields.
Conservation Status: Native.
Plants: Erect perennial, 3-7 ft tall, silvery, widely branching, spiny.
Leaves: Large, firm, spiny, deeply pinnately-divided, underside with a whitish fuzz.
Flowers: Head up to 1 1/2 in wide with pale pink disc flowers, 1 to many heads on a somewhat leafy stalk.
Phenology: Blooms July to October.
Habitat: Dry to moderate moisture; prairies and fields.
Conservation Status: Native.
Very spiny biennials 1-3 m tall, with taproot and spreading fibrous lateral roots. Stem deeply ridged, sub-glabrous to glabrous, much branched. Leaves ovate to lanceolate, 11-40 cm long, all deeply undulate-pinnatifid, the caudate-acuminate primary and secondary lobes tipped by elongate yellow spines, the margins more or less strongly revolute, densely white-woolly beneath, crisped-hispid to subglabrous above. Heads with rather light rose-purple corollas,[rarely white] usually solitary at the end of leafy branches. ln volucre 2-3.5 cm long, the bracts lanceolate with narrow glutinous ridge, acute, the outer abruptly contracted into slightly reflexed or divergent slender spines 3-7 mm long, the inner with erose-scarious tips. Achenes 4-5 mm long.
Johnson, M.E. and H.H. Iltis. 1963. Preliminary reports on the flora of Wisconsin: No. 48. Compositae Family. Wisconsin Academy of Sciences, Arts & Letters. 52:255-342.
Not uncommon in S and SW Wisconsin in sunny habitats, in wet to mesic-dry-prairies, an indicator of mesic prairie (Curtis 1955, 1959), often on railroads, lake shores, in sedge meadows, and occasionally weedy in roadside ditches and well-drained, light soil. Flowering from mid-July to early September; fruiting from early August through September.
This species hybridizes with Cirsium altissimum.
Johnson, M.E. and H.H. Iltis. 1963. Preliminary reports on the flora of Wisconsin: No. 48. Compositae Family. Wisconsin Academy of Sciences, Arts & Letters. 52:255-342.
Other Treatments:
Derek Anderson
Christopher Noll
Steve C. Garske
Chris Noll
Robert W. Freckmann
Robert Bierman
Richard Bauer
Merel R. Black
Derek Anderson
Steve C. Garske
Christopher Noll
Derek Anderson
Derek Anderson
Derek Anderson
Marci Hess
Circium discolor
Aaron Carlson
