Butterfly Weed
Asclepias tuberosa
This is a very common plant, but I've only noticed it this one time. It was along the dusty gravel road running beside Wilson Creek. Leaves are narrow and can be 4-5 inches in length. The flowers are bright orange and are a favorite of swallowtail butterflies. At the end of the season, a pod forms which produces small seeds with a tuft of silky hairs.