Sundrops (Oenothera fruticosa ssp. glauca). Pictures taken June 2, 2009.
Whether this particular plant here at Hort Gardens is native to Indiana depends on your view of Oenothera speciation. In any case it is close to the plant Deam describes in his Flora of Indiana as “usually in moist, black sandy soil in prairie habitats. In marshes and along roadsides” (Oenothera tetragona var. longistipata, syn. Oenothera fruticosa subsp. fruticosa).Link to Oenothera fruticosa ssp. glauca:
Link to Oenothera fruticosa ssp. glauca: