Canada thistle

(Cirsium arvense)

Canada thistleis a non-native, deep-rootedperennial that spreads by seeds andaggressive creeping, horizontal rootscalled rhizomes. Canada thistle cangrow 2 to 4 feet in height. The leavesare oblong, spiny, bright green, andslightly hairy on the undersurface.Unlike other noxious biennial thistleswhich have a solitary flower at theend of each stem, Canada thistleflowers occur in small clusters of 1to 5 flowers. They are about 1 cm indiameter, tubular shaped, and varyfrom white to purple in color.

Canada thistle Factsheet

Canada thistle Biocontrol

Canada Thistle Map