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A Comprehensive Guide to Heart-leaf Milkweed (Asclepias cordifolia)

Heart-leaf Milkweed (Asclepias cordifolia) is a herbaceous perennial that is found in the western United States. This plant is a host to the Monarch Butterfly (Danaus plexippus) and the Queen Butterfly (Danaus gilippus). It can grow to 4 feet tall in the best conditions and has red to purple flowers that bloom in the spring and summer. It is hardy in zones 7-10.

Taxonomy and Naming of Heart-leaf Milkweed (Asclepias cordifolia)

Herbarium specimen of heart-leaf milkweed (Asclepias cordifolia).
Herbarium Specimen — Asclepias cordifolia (Benth.) Jeps. collected in United States of America by The New York Botanical Garden (licensed under CC BY 4.0)
Isotype specimen of heart-leaf milkweed (Asclepias cordifolia).
Isotype Specimen — Acerates cordifolia Benth. collected in United States of America by The New York Botanical Garden (licensed under CC BY 4.0)

Taxonomy

Heart-leaf milkweed (Asclepias cordifolia) was first named Acerates cordifolia by George Bentham, an English botanist. In 1901, it was placed in the Asclepias genus by Willis Jepson, a botanist in California and it has kept this name since. This plant is a member of the Dogbane Family (Apocynaceae).

Synonyms

  • Acerates cordifolia
  • Gomphocarpus cordifolius

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, cordifolia, refers to the heart-shaped leaves.

Common Name and Alternative Names

The common name of this species comes from the shape of the leaves. A variation is heartleaf milkweed, without the hyphen. Another alternative name is purple milkweed, which is descriptive of the flower color.

Physical Description of Heart-leaf Milkweed

Close-up of Red and white flowers of heart-leaf milkweed (Asclepias cordifolia).
Red and white Flowers of Heart-leaf Milkweed — peganum from Henfield, England, CC BY-SA 2.0, via Wikimedia Commons
  • Plant Type: This plant is a herbaceous perennial.
  • Height: 1 to 4 feet
  • Leaves: The leaves are opposite, simple (sometimes ternate), sessile, entire, heart-shaped leaves to ovate and are 3 to 7 inches in length and width.
  • Flower color: Purple, red, violet, or lavender
  • Blooming period: This plant blooms in the spring and summer from March to August during its second year.
  • Fruiting type and period: This plant has follicles that mature in the late summer and fall.

Range of Heart-leaf Milkweed in the United States and Canada

Range of heart-leaf milkweed (Asclepias cordifolia) 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 is native to the western United States and not considered to be rare in any part of its range. It has not been introduced in any other places.

Habitat

Dry rocky woodland habitat.
Dry Woodland Habitat — Patrick Alexander from Las Cruces, NM, CC0 1.0, via Wikimedia Commons

This species grows in open to shaded woodlands and evergreen forests that are dry, rocky, and sloping (Gardenia.net), especially on decomposed granite (Calscape) or talus slopes (Woodson 1954). It can also be found on steep grassy hills in the southern part of its range (Kelch and Murdock 2012).

Hosted Insects

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

This species is a host for the Monarch Butterfly (Danaus plexippus) and also the Queen Butterfly (Danaus gilippus).

Other Supported Wildlife

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

This species is used by other butterflies, bees, 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. However, compared to other milkweeds, it has low toxicity. Heart-leaf milkweed is considered to be poisonous to livestock in Nevada (Fleming 1920) and is poisonous to pets also (Gardenia.net).

Does this plant have any ethnobotanical uses?

This milkweed has been used by the Miwok and Yokut tribes as source of fiber for cordage (Wikipedia). According to the Native American Ethnobotany Database, this plant has been used for candy and pharmaceuticals.

Gardening with Heart-leaf Milkweed

Add Heart-leaf Milkweed to Your Garden

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Plant of heart-leaf milkweed (Asclepias cordifolia) with reddish-white flowers.
Plant of Heart-leaf Milkweed with Flowers — First Light at English Wikipedia, CC BY-SA 3.0, via Wikimedia Commons

Hardiness

This species is hardy in zones 7-10. If your garden is within these zones and you have the right growing conditions (soil and moisture), you may well be able to grow this plant.

Optimal Conditions

This species can handle full sun to partial shade and mesic to dry well-drained soil. This plant is considered to be deer resistant (Calscape).

References

  • Fleming, C.E. 1920. The Narrow-leaved milkweed (Asclepias mexicana) and the broad-leaved or showy milkweed (Asclepias speciosa): plants poisonous to live stock in Nevada. Bulletin of the University of Nevada Agricultural Experiment Station No. 99.
  • Klech, Dean G. and Andrew Murdock. 2012. Flora of the Carquinez Strait Region, Contra Costa and Solano Counties, California. Madrono 59: 47-108.
  • 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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