Canada thistle differs from other species of the true thistle in that there are male and female flower heads, and these are on separate plants. By asexual reproduction, it is possible that a colony of ...

Milk thistle is native to Mediterranean countries but is classified as a weed in the United States. Washington state classifies it as a noxious weed because milk thistle is considered a threat to ...

Despite its name, Canada thistle is not a plant native to Canada. This noxious weed likely came over with early settlers to North America before New England residents blamed its spread on French ...

Canada thistle, a terrestrial herbaceous perennial in the Asteraceae family, is an open-land invasive that prefers disturbed upland areas as well as wet areas with water fluctuations. Canada thistle ...

Bull thistle (Cirsium vulgare) is another biennial (sometimes annual) invasive weed you should be wary of since it's prevalent across all U.S. states. Its giveaways include the 2-inch wide ...