Cirsium horridulum Michaux
Very pretty thistle, not only are the flower portions purple, but the stems are purple as well. Purple thistle can grow anywhere from one to three feet high. The flowers often add another six inches or a foot to the height of the plant. Its leaves also have a wide range of lengths, from eight inches to two feet long. The yellow version of the purple thistle is found more along wet, coastal areas, while most of the inland plants are purple.
Purple thistle can be found along the East Coast, from Canada to Florida, and across the Southern Coast, from Florida to Texas. It can have purple or yellow flowers. http://www.gardeningcentral.org/purple_t...
Interesting tid-bit: One of the most interesting characteristics of the purple thistle is its ability to move toward anything which disturbs it. For instance, if you were to touch the flower with your finger, the anthers (pollen producing part of flower) would move and curl themselves toward you in a protective effort. If something as small as an insect should try to crawl along the flower, the anthers would move to curl themselves around the insect, covering it with pollen at the same time. This movement is called a thigmonastic motion. The plant can use the motion to protect itself from intruders. If you are a lover of butterflies, planting purple thistle in your flower garden will attract many different types of butterflies. For example, it hosts the larvae for the Little Metalmark and the Painted Lady butterflies. Butterflies attracted to the nectar include the Black Swallowtail, Delaware Skipper, Palamedes Swallowtail, Palmetto Skipper, Three-Spotted Skipper, Twin-Spotted Skipper and others. In fact, the purple thistle will also attract bees, beetles, wasps and other kinds of insects.