This is butterfly weed (Asclepias tuberosa). It is in Purdue Hort Gardens along the side of Marsteller St. Picture taken June 12, 2009.
Link to butterfly weed:
Butterfly weed is one of the milkweeds. Look at the little orange flowers closely and see that it has the same form as the other milkweeds. Butterfly weed is native to Indiana but since it is such an attractive flower you are more likely to find it where people have planted it like here at Hort Gardens rather than in its native habitat.
Another link to butterfly weed: