Canada Thistle

(Cirsium arvense)

 

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Canada thistle (Cirsium arvense) is a non-native, deep-rooted perennial that spreads by seeds and aggressive creeping, horizontal roots called rhizomes.  Canada thistle can grow 2 to 4 feet in height.  The leaves are oblong, spiny, bright green, and slightly hairy on the undersurface.  Unlike other noxious biennial thistles which have a solitary flower at the end of each stem, Canada thistle flowers occur in small clusters of 1 to 5 flowers.  They are about 1 cm in diameter, tubular shaped, and vary from white to purple in color.

 

 

 

Canada thistle Map