Description from Butterfly Bushes
Swamp Milkweed, pink flowering (Asclepias incarnata)
Clusters of small pink or white flowers on plants which grow 36″-42″ high. Swamp Milkweed usually grows in moist areas (but it does not require a moist location in the garden). Usually blooming June thru July, this plant serves as a nectar source for several butterfly species and as a host plant for Monarchs. Sorry, no choice of flower color. A US native. Deer resistant.
Perennial, zones 3-8.