Also called Wild Alfalfa, Scurf Pea, Slimleaf Scurfpea and Prairie Turnip,they are legumes that grow woodland and woodland edges. They are probably an imported pea family member with summertime alfalfa-like blooms on spikes.
Late summer the stems break and the plant blows - it is related to tumbleweed. We know that tumbleweed is not native to the U.S. either.
Plains Indians made tea from the roots and burned the plant as a mosquito repellent. And, evidently Psoralea is medicinally important in many cultures.
World Wide Science dot org has a gateway to Oklahoma tallgrass prairie articles and information (here) but nothing on this specific plant.
Oklahoma Panhandle State University has a cool site with wildflower photos - full plant, leaves, flowers, etc. Here's their link to Psoralea.
|Psoralea mature fruit - photo from OK Panhandle State University|
|Annie's Annuals calls Psoralea pinnata Kool Aid Bush - this one is a zone 9 plant.|
|Prairie Moon - native range for Psoralea esculenta|
Have you ever seen this growing? Have you tried to grow it in a wildlife patch? I'm thinking of buying some seeds to try in the back 40 - well I call it the back 40 - it's really just an acre.