Cirsium undulatum (Nutt.) Spreng.
Family: Asteraceae
wavy-leaved thistle
[Carduus megacephalus (A.Gray) Nutt.,  more]
Cirsium undulatum image
Emmet J. Judziewicz  
Etymology: undulatum = wavy
Plants
: perennial, 1'-4' tall, stout forb; stems covered with dense whitish fuzz; usually branched taproots sending up more than one stem
Leaves
: underside with whitish fuzz, pinnately-divided or with coarse teeth
Flowers
: head 1"- 1 1/2" wide with pink to purple disk flowers; inflorescence of many heads in loose clusters; blooms June-Sept.
Fruits
: dry seed, becoming slimy when wet on fluffy, feathery-divided pappus
Habitat
: sun; prairies, hills, railroads; in well drained soil
Conservation Status
: Introduced - adventive
Mostly unbranched biennials, 1-2 m tall, with decurrent leaf bases forming conspicuous green, spiny wings on the stem. Leaves scattered, lanceolate, pilose beneath, pilose to glabrous above, deeply pinnatifid, the lobes obtuse to lanceolate, terminated by a short, firm spine. Heads numerous and very crowded, usually sessile or subsessile, or occasionally on cobwebby peduncles; involucres 9-12 mm high, the bracts without spine tips, or the outer and middle with a spine 1 mm or less long; corollas purple. Achenes 2-3 mm long, white.

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.

Native of temperate Europe to W. Siberia, weedy in the NE. United States, spread to Wisconsin, probably from Northern Michigan, where it has been known since 1935 (cf. Voss 1957: 97). First collected in Vilas Co.: edge of Larix laricina, Picea mariana, Ledum groenlandicum, Sarracenia purpurea, Calopogon pulchellus, Vaccinium oxycoccus sphagnum bog and in adjoining moist to wet roadside ditches, east end of Lac Vieux Desert on Michigan border at entrance to Simpson Estate, July 16, 1961 [fl & fr], Iltis 18212 (WIS) and seen there again in 1962.

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.

Cirsium undulatum image
Emmet J. Judziewicz  
Cirsium undulatum image
Robert R. Kowal  
Cirsium undulatum image
Botanical Illustration  
Cirsium undulatum image
Emmet J. Judziewicz  
Cirsium undulatum image
Cirsium undulatum image
Robert R. Kowal  
Cirsium undulatum image
Cirsium undulatum image
Cirsium undulatum image
Cirsium undulatum image
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