Swamp Milkweed

Kendall County (IL) Forest Preserve District

Swamp Milkweed
Asclepias incarnata [C-value 4]
Milkweed family (Asclepiadaceae)
Blooms mid-June - August

The lovely native Swamp Milkweed is common in our area. This perennial prefers full to partial sun and wet to moist rich soil. Habitats include open to partially shaded areas in floodplain forests, swamps, moist black soil prairies, seeps, fens and marshes. It is 2-6' tall with a central stem that branches occasionally forming ascending lateral stems. The opposite leaves are 3-6" long and ½ -1½" across, narrowly lance-shaped, untoothed and hairless. The upper stems terminate in beautiful pink umbels of flowers spanning about 2-3½" across. Each flower is about ¼" across, consisting of 5 upright whitish hoods and 5 surrounding pink petals that droop downward in the manner of most milkweeds.

Swamp Milkweed at Kendall Co. Extension native garden July 2, 2015

Swamp Milkweed foliage at Lyon Forest Preserve fen July 6, 2013

Monarch Butterfly on Swamp Milkweed at Lyon Forest Preserve fen August 3, 2012 (see note below regarding Monarchs)

Swamp Milkweed at Kendall Co. Extension native garden July 2, 2015

Swamp Milkweed at Rose Hill Subdivision pond July 9, 2012

Swamp Milkweed at Oswego Presbyterian Church Monarch Waystation June 28, 2017

Swamp Milkweed seedpods at Pickerill/Pigott Forest Preserve pond September 21, 2014

Swamp Milkweed seedpods at Pickerill/Pigott Forest Preserve pond September 13, 2014

Swamp Milkweed empty seedpods at Pickerill/Pigott Forest Preserve October 29, 2014

The Milkweeds’ white sap of the leaves and stems is very sticky and distasteful so most insects avoid eating the plant, except for Monarch Butterfly caterpillars which have a tolerance for the acrid juice. The sap is toxic to birds so they quickly learn not to eat the Monarch caterpillars feeding on milkweed sap or those distasteful hatched-out butterflies. So, Monarchs are smart; they only lay their eggs on milkweeds where the caterpillars will have this protection. The extensive use of herbicides in corn and soybean fields here in the Midwest has greatly reduced the field-edge habitats for Milkweeds which in turn reduces the populations of Monarchs and even some beetles that make their summer homes only on milkweeds.

Native Americans used Milkweed as a food and medicine, but it can be toxic to humans if not prepared properly (per Sanders, J). The young shoots, stems, flower buds, immature fruits, and roots of butterfly milkweed were boiled and eaten as a vegetable by various indigenous groups of eastern and mid-western America. The Meskwaki tribe steamed the flower buds as a food source, which was nutritious but not considered very flavorful. The Cherokee drank an infusion of common milkweed root and Virgin's Bower (Clematis species) for backache. They also used the plant as a laxative, an antidote for dropsy, and an infusion of the root for venereal diseases. The Meskwaki and Mohaw used a decoction as a contraceptive; the Iroquois and Navajo to prevent problems after childbirth; and the Chippewa, to produce postpartum milk flow. Other uses included treatment for stomach problems, female issues, chest discomfort, and externally on warts and bee stings. Reminder: see our Do Not Disturb Notice.

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