This weed may invade your land. Be ready to oppose it. The Enemy: Bull thistle (Cirsium vulgare) Strategy: This nonnoxious, biannual, invasive weed can be found throughout Idaho. It has hairy ...

Thistles are classified as an invasive weed in the United States. There are more than 10 identified species. The thistle growing in Streeter’s yard is classified as a Cirsium vulgare or bull ...