Pale to deep pinkish purple flowers are borne in rounded clusters from the leaf axils.

[1] The original range of Asclepias sullivantii was the tall grass prairie, but very little of that habitat remains because of wide spread conversion to farming.

[4] In Minnesota it is listed as threatened species, mainly because of habitat loss, and the remaining plants are found on old railroad right ways that preserve small prairie remnants.

It is restricted to mesic tall grass prairies and seems to have little ability to survive degraded habitats.

[4] Insects that take nectar from the plant include bumblebees and other bees, wasps, ants, flies, and butterflies.