Forest Preserve District of Cook County, Illinois
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The Milkweed
Nature Bulletin No. 162-A   September 26, 1964
Forest Preserve District of Cook County
Seymour Simon, President
David H. Thompson, Senior Naturalist

From the time their first green shoots appear in spring until their dead brown stalks stand above the snow in winter, the milkweeds have a variety of uses and features of interest. The common name refers to the milky juice that oozes from stems and leaves when they are cut or broken. Because the roots of milkweeds were used as drugs, their scientific name, Asclepias, was taken from that of the Greek god of medicine.

The Common Milkweed so often seen in fields, waste places, and along roadsides is the largest and most familiar of the dozen or more kinds found in the Chicago region. The large oval leaves are arranged in pairs on the tall stout stem so that if one pair points east and west, the pair above and the pair below point north and south. Like other milkweeds it is a perennial reproducing both from seeds and long shallow roots that live over the winter.

The "milk" is not the sap of the plant but a special secretion. Extremely bitter, it serves as a protection against most nibbling and grazing animals. On the contrary, milkweed leaves are the only food of the caterpillar of our monarch butterfly. Also, this milk quickly seals any wound on the plant because it contains latex and, as it dries, becomes very sticky and elastic, turning into a kind of crude rubber. See how a drop of the milk makes your thumb and fingers cling together. Like rubber cement, it cannot be washed off with soap and water. During World War II when imports of natural rubber from the rubber tree were cut off, the milkweed was tested as a possible substitute.

In spring, the tender shoots can be boiled and eaten like asparagus. In autumn, the roots are still collected and marketed in small amounts for the drugs they contain. Formerly, these were common remedies for lung trouble and rheumatism. The Indians made twine from the coarse strong fibers in the bark of the stalk. The dead stalks with their picturesque empty pods are favorites for making winter bouquets and art objects.

The common milkweed bears clusters of dull purple flowers with a heavy cloying odor which, though unpleasant to us, is unusually attractive to bees and butterflies. Each flower of the cluster has an elaborate trap to catch the legs of these insects and remove any pollen they may carry. Sometimes the insect cannot escape and pays with its life for the nectar it came to drink. Indians produced sugar by shaking the honeydew from its blooms in early morning and drying it.

Each cluster of blossoms is followed by one or two large warty pods with a seam along one side which pops open when the pod becomes ripe and dry. Inside is a closely packed roll of several hundred flat brown seeds arranged like scales on a fish, each with a folded parachute of fine silky fibers. Gradually, these parachutes open and the seeds are carried away on the fall winds. During the war, hundreds of tons of milkweed pods were gathered by school children and the silky fluff processed as a substitute for kapok, used to pad life jackets and flying suits.

The Butterfly Weed or Pleurisy Root with its glowing orange flowers is the most beautiful of the milkweeds. Unlike other milkweeds, it lacks the milky juice. The Indians used its roots for medicine and cooked the green pods with their buffalo meat much as we use green peppers. The Swamp Milkweed bears masses of brilliant red or rose-purple flowers which are followed by pencil-slender pods. The dainty Whorled Milkweed has tiny greenish white flowers and very slender leaves. Mixed with hay crops it can be poisonous to livestock.

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