Vascular Plants of Wisconsin

Cirsium vulgare (Savi) Ten.
bull thistle
Family: Asteraceae

native: no
type: forb; biennial

plant flower head fruiting head

post-fruiting head

stem leaf

winged stem basal rosette
(first year plant)
 

Cirsium vulgare is a large, spiny plant of sunny disturbed sites. The leaf blade continues down the stem from the point of attachment resulting in "winged" stems. The margins and lobe tips of leaves and stem wings, and bracts of the flower heads all bear sharp, stiff spines. What appears to be a large purple flower, is really a "head" of flowers. When mature, the achenes each bear a cluster of feathery bristles known as a "pappus" that assist in dispersal by the wind.

Cirsium vulgare is an alien weedy species that has become established throughout the continental United States. It is found throughout Wisconsin in sunny sites, and is especially prominent in farming areas, but can be expected on productive soils just about anywhere. The plants are biennial, meaning that they produce a basal rosette of leaves in the first growing season and then send up a flowering stalk in the second year. After they flower and produce mature fruit in the second year they die. There are 10 species of thistles (in the genus Cirsium) reported in Wisconsin. Five of the species are aliens and they are the most common. Two of the native species are threatened in Wisconsin and one of those, dune thistle (Cirsium pitcheri) is also federally threatened.

 


known distribution based on vouchers

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