Butterfly Milkweed

Butterfly Milkweed

Butterfly Milkweed
Photo by Jim Mason

Common Name:
Butterfly Milkweed

Scientific Name:
Asclepias tuberosa

Award:
Kansas Wildflower of the Year - 1999

A June prairie is incomplete without the vivid presence of Butterfly Milkweed. This outstanding member of the Asclepiadaceae, or Milkweed family, may be found from New England to Utah and south to Arizona, Texas and Mississippi. It is unique in not having milky sap, as do other members of the genus.

The flowers of milkweeds have a very complex structure which invite close inspection with a hand lens. They are divided into five equal parts with unique upward-projecting hoods (red parts in the picture) and conventional petals below. The hoods are shaped like little scoops and the nectar is secreted at the bottom inner surface of each. Also hidden there are the Y-shaped pollinia, or pollen sacs, which can hook onto the leg of a visiting insect and thus get carried to the next flower. It takes a fairly strong insect to yank itself (and the pollinium) loose. Sometimes smaller insects will either get trapped or lose a leg trying to free themselves after getting their leg hooked into a pollinium.

Photo by Jim Mason

Milkweeds produce pods full of small papery brown seeds which have long silky white hairs attached to them. The pods split open on one side when the seeds are mature. The hairs allow the wind to scatter the seed. The pods of Butterfly Milkweed are slender and have a long tapering point.

Butterfly Milkweed is noted for medicinal properties. One of its old nicknames is Pleurisy Root. It was widely used by Native Americans for treating throat and lung ailments and for cuts and sores. It was listed in the U.S. Pharmacopoeia from 1820 to 1905 and in the National Formulary form 1916 to 1936. Extracts from the roots of Butterfly Milkweed have been shown to be active against tuberculosis cultures. The identified active compounds in milkweeds include a potent class of chemicals known as cardiac glycosides. It is these chemicals that are utilized by Monarch butterfly caterpillars for their own protection. As they eat milkweed they store the cardiac glycosides in their exoskeleton, making themselves toxic to predators such as birds.

Butterfly Milkweed and a visitor
Photo by Bob Gress

Practically any type of nectar-loving insect is attracted to the flowers. The picture shows a Coral Hairstreak butterfly looking for its lunch. Every species of butterfly in the neighborhood will be attracted to Butterfly Milkweed. The flower heads of milkweeds are especially appealing to butterflies because they have so many nectaries (5 per flower and many flowers per inflorescence). This gives a high probability of finding food even if another butterfly was just there before it. As you can see, the flowers vary in color from yellow to a vivid deep orange.

Many milkweeds spread by lateral roots (rhizomes). Butterfly Milkweed grows in a single clump from a woody rootstock. Since it is not invasive it is a good candidate for the home garden, compared to other milkweeds. Its beauty, attractiveness for butterflies and availability in the garden trade resulted in it being chosen as the Kansas Wildflower of the Year for 1999. A committee made of members of the Kansas Wildflower Society, the Kansas Associated Garden Clubs and Botanica, the Wichita Gardens bestows this honor each year. Purple Coneflower was chosen in 1998. If you are looking for a native prairie wildflower for your garden, Butterfly Milkweed is an excellent choice.

Watch for Butterfly Milkweed in roadside habitat and prairies during early summer. You will not only find a delight for the eye, but a lot of butterflies and other insects as well!

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- This page was spun by Jim Mason -

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Great Plains Nature Center
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Wichita, KS 67220-2200 Call: 316-683-5499 Fax: 316-688-9555