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A Comprehensive Guide to Four-leaf Milkweed (Asclepias quadrifolia)

Four-leaf Milkweed (Asclepias quadrifolia) is a herbaceous perennial that is found in the mid-western and eastern United States. This plant is a host to the Monarch butterfly (Danaus plexippus) and Queen butterfly (Danaus gilippus). It can grow from 1 to 3 feet tall and has flowers that are pink to white (cream) that bloom from April to July. It is hardy in zones 5-8.

Taxonomy and Naming of Four-leaf Milkweed (Asclepias quadrifolia)

Herbarium specimen of four-leaf milkweed (Asclepias quadrifolia).
Herbarium Specimen — Asclepias quadrifolia Jacq. collected in United States of America by The New York Botanical Garden (licensed under CC BY 4.0)

Taxonomy

Four-leaf milkweed (Asclepias quadrifolia) was named and described by Nikolaus Joseph von Jacquin, a European botanist, in 1767. The species has kept this name since. This plant 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, quadrifolia, is Latin for four leaves, and is descriptive of the four whorled leaves.

Common Name and Alternative Names

The common name describes the four whorled leaves. A variant of this name is the four-leaved milkweed. Another common name, whorled milkweed, also describes the whorled leaves.

Physical Description of Four-leaf Milkweed (Asclepias quadrifolia)

Plant of four-leaf milkweed (Asclepias quadrifolia) in a wooded area.
Plant of Four-leaf Milkweed — “Asclepias quadrifolia” by kodendakj is marked with CC0 1.0.

Description

  • Plant Type: This plant is a herbaceous perennial.
  • Height: 1 to 3 feet
  • Stem: green to purple with pubescence
  • Leaves: The leaves are opposite, whorled, simple, entire, and lanceolate to ovate. They range in size from 2 to 6 inches in length and 1 to 3 inches in width. The lowermost leaves may be subsessile to sessile (Woodson 1954). The veins underneath may be pubescent (House 1918).
  • Flower color: white (cream) to pink.
  • Blooming period: This plant blooms from April to July.
  • Fruiting type and period: This plant has follicles that mature in the late summer and fall.

Range of Four-leaf Milkweed (Asclepias quadrifolia) in the United States and Canada

Range map four-leaf milkweed (Asclepias quadrifolia) in the United States and Canada.
Kartesz, J.T., The Biota of North America Program (BONAP). 2015. North American Plant Atlas. (https://bonap.net/napa). Chapel Hill, N.C. [maps generated from Kartesz, J.T. 2015. Floristic Synthesis of North America, Version 1.0. Biota of North America Program (BONAP). (in press)].

This milkweed species grows in the mid-western and eastern United States except for Maine, Delaware, and Florida. It is considered to be rare in the states of New Hampshire, Vermont, New Jersey, Kansas, and the province of Ontario in Canada.

Habitat

Roadside in Europe with wildflowers.
Roadside of Wildflowers — Roadside verge full of wildflowers by Christine Johnstone, CC BY-SA 2.0, via Wikimedia Commons

This species grows in open areas such as roadsides, pastures, and prairies that are dry and rocky and often disturbed in some way. It has also been listed on rocky wooded slopes at the Arnold Arboretum (Palmer 1930) and in growing in dense forest understories (Fishbein 1999).

Hosted Insects

Monarch butterfly on green flower.
Green Flower with Monarch Butterfly (Danaus plexippus) — U.S. Fish and Wildlife Service, Public domain, 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 bees in the summer and fall.

Frequently Asked Questions about Four-leaf Milkweed (Asclepias quadrifolia)

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 notes that this species has been used as an analgesic, for skin diseases, veterinary medicine, and for hunting and fishing.

How is this plant distinguished from other milkweeds?

Four-leaf milkweed occurs in the series “syriacea” of the Asclepias genus and leaves that do not clasp the stem and are whorled at the first node of the stem. Other species that are similar are pinewoods milkweed (Asclepias humistrata), which has clasping leaf bases, and common milkweed (Asclepias syriaca) which has opposite leaves that do not have whorling (Rosatti 1989).

Another area of confusion is that this plant shares a common name, whorled milkweed, with another species, Asclepias verticillata. However, A. verticillata, has greenish-white flowers versus the pinkish-white flowers of the species in this post.

Is this plant invasive?

This species can grow in places that have been disturbed, but there is nothing in the literature indicating that it is invasive. Gardenia.net states this plant spreads by seed and rhizomes, but it is not invasive.

Gardening with Four-leaf Milkweed (Asclepias quadrifolia)

Plant of four-leaf milkweed (Asclepias quadrifolia) in a wooded area.
Plant of Four-leaf Milkweed — User:Halpaugh, CC BY-SA 3.0, via Wikimedia Commons

Hardiness

This species is hardy in zones 5-8. 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 grows best in places it can receive full sun to part-shade. It favors dry rocky soils.

References

  • Fishbein, Mark and S.P. Lynch. 1999. Asclepias jorgeana (Asclepiadaceae), a new milkweed from montane western Mexico. Novon 9: 179-184.
  • House, Homer D. 1918. Wildflowers of New York. (Albany, NY: University of the state of New York) Memoirs of the New York State Museum.
  • Palmer, Ernest J. 1930. The Spontaneous Flora of the Arnold Arboretum. Journal of the Arnold Arboretum 11(2): 63-119.
  • Rosatti, T.J. 1989. The genera of suborder Apocynineae (Apocynaceae and Asclepiadaceae) in the southeastern United States [concl.] Journal of the Arnold Arboretum 70:443-514.
  • 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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