Asclepias viridiflora
An uncommon plant in Indiana, I've only seen it once.
A flowering stem at Baseline Barrens, south of Salem, 6/27/04.
Side view of flowers at Baseline Barrens, 6/27/04.
Front view of flowers at Baseline Barrens, 6/27/04.
A flowering stem at Baseline Barrens, south of Salem, 6/27/04.
Side view of flowers at Baseline Barrens, 6/27/04.
Front view of flowers at Baseline Barrens, 6/27/04.