I always thought teasel can be pretty in its various stages. But I didn't know it is considered invasive in the United States. Here is what Wikipedia has to say about it: "Teasel is also considered an invasive species in the United States. It is known to form a monoculture, capable of crowding out all native plant species, and therefore is discouraged and/or eliminated within restored open lands and other conservation areas."

On the other hand, teasel root is considered beneficial in the treatment of some diseases.
See - http://www.honeycolony.com/article/teasel-root-heal/