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A Comprehensive Guide to Michaux’s Milkweed (Asclepias michauxii)

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Michaux’s Milkweed (Asclepias michauxii) is a herbaceous perennial that is native to the southeastern United States. This plant is a host to the Queen (Danaus gilippus) and Monarch (Danaus plexippus) butterflies. Growing from 4 to 16 inches tall, this species grows in savannahs and pinelands and has greenish-white flowers that bloom from April to June. It is hardy in zones 7-11.

Taxonomy and Naming of Michaux’s Milkweed (Asclepias michauxii)

Herbarium specimen of Michaux's milkweed (Asclepias michauxii).
Herbarium Specimen — Asclepias michauxii Decne. collected in United States of America by The New York Botanical Garden (licensed under CC BY 4.0)

Taxonomy

Michaux’s Milkweed (Asclepias michauxii) was originally named and described by Joseph Decaisne, a French botanist, in 1844. This species has kept the same name since and is a member of the Dogbane Family (Apocynaceae).

Meaning of the Scientific and Common Names

Scientific Name

The genus name, Asclepias, is named for the Greek god of healing, Asklepios (Flora of Wisconsin). The species name, michauxii, is in honor of Andre Michaux, an earlier French botanist.

Common Name and Alternative Names

The common name comes from the last name of Andre Michaux, an earlier French botanist in America.

Physical Description of Michaux’s Milkweed (Asclepias michauxii)

White flowers of Michaux's milkweed (Asclepias michauxii).
Flowers of Michaux’s Milkweed — Asclepias michauxii Decne. observed in United States of America by John Kees (licensed under CC0 1.0)

Description

  • Plant Type: This plant is a herbaceous perennial
  • Height: 4 to 16 inches tall
  • Stem: The stem may be ascending or reclining. The stems may be puberulent (Small 1903).
  • Leaves: The leaves are opposite (subopposite), simple, sessile, and linear to filiform in shape (Woodson 1954). The leaves are 6 to 12 inches long and about 0.1 to 0.2 inches wide. The margins of the leaves are sometimes revolute (Woodson 1954).
  • Flower color: Greenish-white with a purplish tinge.
  • Blooming period: This plant blooms from April to June.
  • Fruiting type and period: This plant has follicles that mature in the late summer and fall.

Range of Michaux’s Milkweed (Asclepias michauxii) in the United States and Canada

Range map of Michaux's milkweed (Asclepias michauxii) in the United States and Canada.
Range Map Credit: Kartesz, J.T., The Biota of North America Program (BONAP). 2023.(website https://bonap.org/). Chapel Hill, N.C. [maps generated from Kartesz, J.T. 2023. Floristic Synthesis of North America, Version 1.0. Biota of North America Program (BONAP). (in press)]

This milkweed species is native to the southeastern United States.

Habitat

Longleaf pine barren habitat in Florida.
Pine Barren Habitat — National Archives and Records Administration, Public domain, via Wikimedia Commons

This species grows in pine savannas, pine-oak woods, marl outcrops (floraofalabama), sandy pine barrens (Woodson 1954), and dry pinelands (Weakley 2022).

Hosted Insects

Queen Butterfly on Twig.
Queen Butterfly (Danaus gilippus) — Korall, CC BY 3.0, via Wikimedia Commons

Other Supported Wildlife

Bumblebee on pink flower.
Bumblebee on Flower — Weerlicht, CC0, via Wikimedia Commons

This species is a nectar source to other butterflies, skippers, bees, and wasps during the growing season.

Frequently Asked Questions about Michaux’s Milkweed (Asclepias michauxii)

Is this plant poisonous?

Like other milkweeds, it has cardiac glycosides (cardenolides) and is considered to be poisonous with ingestion.

Does this plant have any ethnobotanical uses?

The Native American Ethobotanical Database does not cite this species specifically, but milkweeds in general have been used for pharmaceuticals, fibers, and foods.

How is this plant distinguished from other milkweeds?

This species is similar to the long-leaf milkweed (Asclepias longifolia), but differs in that this species has only one umbel, while long-leaf milkweed generally has more than one umbel. There are other species similar to Michaux’s milkweed but they are in other regions of the United States or in Mexico and can be separated by their range.

Is this plant invasive?

This plant has not been noted as being weedy and is rare throughout its range.

Is this plant deer resistant?

This plant has been noted as being deer resistant by Shoot Gardening.

Gardening with Michaux’s Milkweed (Asclepias michauxii)

Plant of Michaux's milkweed (Asclepias michauxii) with white flowers.
White Flowers of Michaux’s Milkweed — “Asclepias michauxii” by mcferny is licensed under CC BY 4.0.

Hardiness

This species is hardy roughly in zones 7-11. If your garden is within these zones and you have the right growing conditions (soil, moisture and exposure), you may well be able to grow this plant. However, if planted outside of its range, the hosted species may not recognize the plant or be harmed by ingesting a different species with an unfamiliar chemical composition.

Optimal Conditions

This species can grow in full sun to partial-shade in well-drained soil.

References

  • Small, John Kunkel. 1903. Flora of the southeastern United States; being descriptions of the seed-plants, ferns and fern-allies growing naturally in North Carolina, South Carolina, Georgia, Florida, Tennessee, Alabama, Mississippi, Arkansas, Louisiana and the Indian territory and in Oklahoma and Texas east of the one-hundredth meridian. (New York: self-published).
  • Weakley, A.S., and Southeastern Flora Team 2022. Flora of the southeastern United States. University of North Carolina Herbarium, North Carolina Botanical Garden.
  • Woodson, Robert E. 1954. The North American Species of Asclepias L. Annals of the Missouri Botanical Garden 41: 1-211.
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Robert Coxe

Robert Coxe

Robert Coxe is a professional ecologist and botanist who has worked as the State Ecologist of Delaware and as an ecologist for the Western Pennsylvania Conservancy. He is also a former Past-President of the Pennsylvania Academy of Science. He currently is an innkeeper at McMullen House Bed & Breakfast LLC and a web designer and owner for Silphium Design LLC.

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