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A Comprehensive Guide to Poke Milkweed (Asclepias exaltata)

Poke Milkweed (Asclepias exaltata) is a herbaceous perennial that grows from the mid-west to eastern North America. This plant is a host to the Monarch (Danaus plexippus). It can grow to 6 feet tall and has green to white flowers that bloom from April to August. It is hardy in zones 3-9.

Taxonomy and Naming of Poke Milkweed (Asclepias exaltata)

Herbarium specimen of poke milkweed (Asclepias exaltata).
Herbarium Specimen — Asclepias exaltata L. collected in United States of America by The New York Botanical Garden (licensed under CC BY 4.0)
Type specimen of poke milkweed (Asclepias exaltata).
Type Specimen — Asclepias bicknellii Vail collected in United States of America by The New York Botanical Garden (licensed under CC BY 4.0) Type Specimen

Taxonomy

Poke milkweed (Asclepias exaltata) was named and described by Carl von Linnaeus, in 1753. It has kept this name since. This plant is a member of the Dogbane Family (Apocynaceae).

Synonyms

  • Asclepias phytolaccoides
  • Asclepias bicknellii

Meaning of the Scientific Names and Common Names

Scientific Name

The genus name, Asclepias, is named for the Greek god of healing, Asklepios (Flora of Wisconsin). The species name, exaltata, comes from the Latin word for “elevated”, possibly referring to the height of the plant.

Common Name and Alternative Names

The common name likely comes the resemblance of the plant to pokeweed (Phytolacca americana) and further evidence of this is a synonym, which is called A. phytolaccoides. The Illinois Wildflowers site states this as well. Another name for this plant is tall milkweed, which goes along with the species name.

Physical Description

White flowers of poke milkweed (Asclepias exaltata) in a wooded area.
Flowers of Poke Milkweed (Asclepias exaltata) — homeredwardprice, CC BY 2.0, via Wikimedia Commons
  • Plant Type: This plant is a herbaceous perennial.
  • Height: 2 to 6 feet
  • Stem: glabrous (hairless) or very slightly hairy and green to purplish in color
  • Leaves: The leaves are opposite, simple, entire, and ovate to elliptic to egg-shaped. They range in size from 2 to 10 inches in length and 1 to 4 inches in width. The leaves are white underneath.
  • Flower color: The flowers are white to green with some accents of rose, purple, or blue.
  • 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 Poke Milkweed (Asclepias exaltata) in the United States and Canada

Range map of poke milkweed (Asclepias exaltata) 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 species grows from the mid-west to the eastern United States and in Ontario and Quebec in Canada. It is considered to be rare in the states of Alabama, Delaware, Rhode Island, and Vermont and in the province of Quebec.

Habitat

Floodplain Forest in Delaware.
Floodplain Forest — Author Image

This species grows in moist woods, thickets (House 1918 and Bohumil 1906), roadsides and wood edges (Witmer 1911), woodlands, and meadows.

Hosted Insects

Monarch butterfly on green flower.
Monarch Butterfly on Green Flower — U.S. Fish and Wildlife Service, Public domain, via Wikimedia Commons

This species is a host for the Monarch Butterfly (Danaus plexippus).

Other Supported Wildlife

Wood thrush on branch.
Wood Thrush — Andy Reago & Chrissy McClarren, CC BY 2.0, via Wikimedia Commons

This species produces abundant nectar and is used by other butterflies, bees, beetles, and birds in the late summer and fall.

Frequently Asked Questions

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 shows that this plant has been used as a gastrointestinal aid.

How is this plant distinguished from others?

This milkweed is similar to the common milkweed (Asclepis syriaca), but has fewer flowers in a cluster than the common milkweed. Common milkweed is known to hybridize with this milkweed, producing plants that are intermediate between both (Illinois Wildflowers).

Is this plant invasive?

According to the Prairie Moon Nursery, this milkweed is among the least aggressive. This has been observed in the woods around Pennsylvania, where there is often one or only a few plants present when found. Poke milkweed has a taproot, so it does not spread by rhizomes.

Gardening with Poke Milkweed (Asclepias exaltata)

Add Poke Milkweed to Your Garden

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Greenish-white flowers of poke milkweed (Asclepias exaltata) in a wooded area.
Greenish-white Flowers — Dendroica cerulea, CC BY 2.0, via Wikimedia Commons

Hardiness

This species is hardy in zones 3-9. 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.

Optimal Conditions

This species grows best in moist soil where it can receive part shade to shade. According to Minnesota Wildflowers, this is among the most shade resistant of the milkweeds.

References

  • Bohumil, Shimek. 1906. Flora of Winneshiek County. Des Moines, IA. (Book)
  • House, Homer. 1918. Wild flowers of New York. Memoirs of the New York State Museum no. 15.
  • Witmer, Stone. 1911. The plants of Southern New Jersey; with especial reference to the flora of the Pine Barrens and geographic distribution of the species. Trenton, NJ. (Book)
  • 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 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.