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Carolina Milkweed (Asclepias cinerea), a Comprehensive Guide in 10 Sections

Carolina Milkweed (Asclepias cinerea) is a herbaceous perennial that is found in the southeastern United States. This plant is a host to the Queen (Danaus gilippus) and Monarch (Danaus plexippus) butterflies. Growing from 1 to 2.5 feet tall, this species has white to lavender flowers that bloom from May to August. It is hardy in zones 8-10.

Taxonomy and Naming of Carolina Milkweed (Asclepias cinerea)

Herbarium specimen of carolina milkweed (Asclepias cinerea).
Herbarium Specimen — Asclepias cinerea Walter collected in United States of America by The New York Botanical Garden (licensed under CC BY 4.0)
Neotype specimen of carolina milkweed (Asclepias cinerea).
Neotype Specimen — Harvard College, Public Domain

Taxonomy

Carolina milkweed (Asclepias cinerea) was named and described by Thomas Walter, an American botanist, in Flora Caroliniana (1788). The species has kept this name since and is a member of the Dogbane Family (Apocynaceae). The neotype of the species is a specimen from Hampton County, SC (Ward 2007).

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, cinerea, comes from the latin word, cinereus, which means gray tinged with black or ash-colored.

Common Name and Alternative Names

The common name describes the native location of the plant. Another common name, ashy milkweed (Lounsberry, et al. 1899), describes the flower color.

Physical Description

Purplish flowers of carolina milkweed (Asclepias cinerea).
Flowers of Carolina Milkweed — Asclepias cinerea Walter observed in United States of America by Amber M. King (licensed under CC BY 4.0)
  • Plant Type: This plant is a herbaceous perennial.
  • Height: 1 to 2.5 feet
  • Stem: slightly pubescent in lines
  • Leaves: The leaves are opposite, simple, entire, and linear, filiform to lanceolate in shape. The leaves range in size from 2 to 3.5 inches in length and 0.08 to 0.1 inches in width (Woodson 1954). The leaves have been described as rigid (Lounsberry 1901).
  • Flower color: White (Woodson 1954), ashy-gray (Weakley 2022) to lavender (Florida Wildflowers).
  • Blooming period: This plant blooms from May to August.
  • Fruiting type and period: This plant has follicles that mature in the late summer and fall.

Range of Carolina Milkweed (Asclepias cinerea) in the United States and Canada

Range map of carolina milkweed (Asclepias cinerea) 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 found in the southeastern United States from South Carolina west to Mississippi. It is considered to be rare in the states of Mississippi and Alabama.

Habitat

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

This species grows in savannas, moist meadows and grasslands, pine barrens (wet or dry), and sandy ridges.

Hosted Insects

Purple coneflower (Echinacea purpurea) with Monarch butterfly.
Monarch Butterfly on Purple Coneflower — Robert Coxe, Image

Other Supported Wildlife

Bumblebee on flower.
Flower with Bumblebee — Rosendahl, Public domain, via Wikimedia Commons

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

Frequently Asked Questions

Is this plant poisonous?

Like other milkweeds, it has cardiac glycosides (cardenolides) and is considered to be poisonous with ingestion. Because of the poisonous nature of the plant it is deer resistant.

Does this plant have any ethnobotanical uses?

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

How is this plant distinguished from other milkweeds?

This species is similar to the Florida milkweed (Asclepias feayi) and the southern milkweed (Asclepias viridula), but both of these species have shorter pedicels.

Is this plant invasive?

This species has not been listed as invasive in the literature. This could be due to the limited habitat.

Gardening with Carolina Milkweed (Asclepias cinerea)

Leaves and stem of carolina milkweed (Asclepias cinerea).
Vegetative Plant of Carolina Milkweed — Asclepias cinerea Walter observed in United States of America by Scott Allen Davis (licensed under CC BY 4.0)

Hardiness

This species is hardy in zones 8-10. 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 partial shade.

References

  • Lounsberry, Alice, Ellis Rowan, and Nathaniel Britton. 1899. A Guide to the Wildflowers. New York: New York Botanical Garden.
  • Lounsberry, Alice and Ellis Rowan. 1901. Southern wild flowers and trees, together with shrubs, vines, and various forms of growth found through the mountains, the middle district and low country of the South. (New York: F.A. Stokes Company).
  • Ward, Daniel. 2007. Thomas Walter Typification Project, IV: Neotypes and Epitypes for 43 Walter Names, of Genera A through C. Journal of The Botanical Research Institute of Texas. 1: 1091-1100.
  • Weakley, A.S. and the 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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