Cirsium arvense (L.) Scop.

Locations ofCirsium arvense (L.) Scop. in Virginia

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Detail

Family
Asteraceae
Botanical Name
Cirsium arvense (L.) Scop.
Common Name
Canada Thistle, Field Thistle
Synonym(s)
Cirsium arvense (L.) Scop. var. arvense; Cirsium arvense (L.) Scop. var. horridum Wimmer & Graebner
Flora of Virginia Name/Status
Cirsium arvense (L.) Scop. var. arvense + Cirsium arvense (L.) Scop. var. horridum Wimmer & Graebner
Comments
A number of infraspecific segregates have been proposed based on pubescence, leaf division, and spininess. The very spiny var. horridum Wimmer & Graebner, in particular, is striking in its extreme expression, yet grades continuously into other, less spiny forms. FNA notes that "although extreme variants can be strikingly different, they are connected by such a web of intermediates that there seems to be little value in according any of them formal taxonomic recognition."
Habitat
A pernicious weed of various open, disturbed habitats that has spread rapidly in Virginia over the last several decades. It is frequent to common in the mountains and northern Piedmont, infrequent to rare (but spreading and possibly undercollected) elsewhere.
Native Status
Introduced

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