Swamp Milkweed
Asclepias incarnata (Swamp Milkweed, Rose Milkweed, Swamp Silkweed, and White Indian Hemp) is a herbaceous, perennial plant species native to North America. It is found growing in damp to wet soils and also is cultivated as a garden plant for its attractive flowers, which are visited by butterflies and other pollinators due to its copious production of nectar. Like most other milkweeds, it has sap containing toxic chemicals, a characteristic that repels insects and herbivorous animals.
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. The emerging caterpillars feed on the leaves.
The plants have specialized roots for living in heavy wet soils. The scented, thick, white roots are adapted to live in environments low in oxygen. Blooming occurs in mid to late summer and after blooming; long, relatively thin, rounded, pods are produced that grow uprightly. The pods split open in late summer to late fall, releasing seeds that are attached to silky hairs, which act as parachutes that carry the seeds on the currents of the wind.
Source: en.wikipedia.org/wiki/Asclepias_incarnata - 14.12.2011