Sub-category: Milkweed family
A herbaceous perennial plant, upright, 100 to 150 cm tall plant, growing from thick, fleshy, white roots. Typically, its stems are branched and the clump forming plants emerge in late spring after most other plants have begun growth for the year. The oppositely arranged leaves are 7.5 to 15 cm long and 1 to 4 cm wide and are narrow and lance-shaped, with the ends tapering to a sharp point. The plants produce small, fragrant, pink to mauve (sometimes white) colored flowers in rounded umbels. The flower color may vary from darker shades of purple to soft, pinkish purple and a white flowering form exists as well. The flowers have five reflexed petals and an elevated central crown. After blooming, green seed pods, approximately 12 cm long, are produced that when ripe, split open. They then release light to dark brown, flat seeds that are attached to silver-white silky-hairs ideal for catching the wind.
Swamp milkweed prefers moisture retentive to damp soils in full sun to partial shade and typically, is found growing wild near the edges of ponds, lakes, streams, and low areas - or along ditches. It is one of the best attractors of the monarch butterfly, which feeds on the flowers and lays her eggs on the plants, and as such is often found in butterfly and flower gardens. Blooms in early to mid-summer.