Cirsium spp.

Similar to Carduus nutans L.

Musk thistle is similar to Canada thistle (Cirsium arvense) and bull thistle (Cirsium vulgare), both of which are also non-native. There is some evidence of hybridization occurring between musk thistle and non-native plumeless thistle (Carduus acanthoides). Musk thistle is distinguished from other thistles by the usually large disk-shaped flowers.