Canada thistle is one
of the big nasty perennial weeds that infest millions of acres (hectares
too). They invade pastures and row crop and just about any land they can.
They seem to thrive in drier habitats, although they are very open-minded
about invading your farm. Their success is in no small part due to their
very aggressive rootstock-root-bud system, as seen in the picture on the
left.
Once buds on the rootstock
germinate they form seedlings (left).
Leaves are spiny and
hurt when you try to pull them with bare hands. The small plant (left)
didn't seem to be hurt too much by the severe summer hail storm that took
place just before I took this picture (left).Leaves and stems:
