Swamp milkweed is a tall, herbaceous (not-woody) plant. The leaves grow opposite one another along the stems and are lance-shaped (long and skinny with a pointed tip). Swamp milkweed flowers are 5-petaled, appear in the summer and are pink to a deep magenta but can also be white. After blooming, the plant produces green seed pods. When the pods are ripe, they split open to release seeds that are attached to white, silky hairs that help them disperse with the wind. As its name suggests, Swamp milkweed is generally found in damp soils, often near bodies of water.
Swamp milkweed is an important plant for pollinators, especially the Monarch butterfly. Like other milkweeds, Swamp milkweed contains a chemical called cardiac glycoside which is toxic to most animals if ingested (including humans). The caterpillars of the monarch butterfly can eat the plant without being harmed and can take up the cardiac glycosides to protect them against predators that might be tempted to eat them. Swamp milkweed has also been used by humans, especially indigenous groups for a variety of uses. They harvested dry plants for their fibers to make ropes and, with proper preparation, were able to create remedies for a variety of ailments including chest pains, stomach problems, and childbirth issues.