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A Comprehensive Guide to Emory’s Milkweed (Asclepias emoryi)

Emory’s Milkweed (Asclepias emoryi) is a herbaceous perennial that is native to the states of Texas and New Mexico in the United States. This plant is a host to the Queen (Danaus gilippus) and Monarch (Danaus plexippus) butterflies. Growing from 0.3 to 0.6 feet tall, this species has white to green flowers that bloom from April to August. It is hardy in zones 7-10.

Taxonomy and Naming of Emory’s Milkweed (Asclepias emoryi)

Herbarium specimen of Emory's milkweed (Asclepias emoryi).
Herbarium Specimen — Asclepias emoryi (Greene) Vail ex Small collected in United States of America by The New York Botanical Garden (licensed under CC BY 4.0)


Emory’s Milkweed (Asclepias emoryi) was originally named and described by Edward Greene, an American botanist, as Podostemma emoryi in 1897. After going through a succession of names it was given its current name in 1935 by Anna Vail, but was invalidly published. This naming was later published validly by Ivar Tidestrom in 1935 (Tidestrom 1935). John Small, another botanist, also had a hand in publishing and describing this species. The species has kept this name since this time 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, emoryi, is a Latinized version of Emory.

Common Name and Alternative Names

The common name probably comes from the name of another botanist, but no definitive source could be found.

Physical Description of Emory’s Milkweed (Asclepias emoryi)

Close-up of white flower of Emory's milkweed (Asclepias emoryi).
White Flower of Emory’s Milkweed — Asclepias emoryi (Greene) Tidestr. observed in United States of America by Jo Roberts (licensed under CC BY 4.0)


  • Plant Type: This plant is a herbaceous perennial
  • Height: 0.3 to 0.6 feet
  • Stem: The stem is ascending to decumbent and slightly pubescent (Woodson 1954).
  • Leaves: The leaves are opposite, simple, entire, and ovate to lanceolate in shape. The leaves are 1.5 to 3 inches long and about 1.5 to 2 inches wide. The leaves are evergreen (hortipedia).
  • Flower color: white, greenish-white, to greenish-yellow
  • Blooming period: This plant blooms from April to August.
  • Fruiting type and period: This plant has follicles that mature in the late summer and fall.

Range of Emory’s Milkweed (Asclepias emoryi) in the United States and Canada

Range map of emory's milkweed (Asclepias emoryi) in the United States and Canada.
Range Map Credit: Kartesz, J.T., The Biota of North America Program (BONAP). 2023.(website 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 states of Texas and New Mexico and the northern reaches of Mexico.


Prairie habitat in United States.
Prairie Habitat — USFWS Mountain-Prairie, Public domain, via Wikimedia Commons

This species grows in sandy prairies and disturbed places such as roadsides and railways.

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 Emory’s Milkweed (Asclepias emoryi)

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 specifically mention this species, but milkweeds in general have been used for foods, pharmaceuticals, and fibers.

How is this plant distinguished from other milkweeds?

This species is similar to the zizotes milkweed (Asclepias oenotheroides), but the zizotes milkweed has an unlobed hood, whereas this species has a lobed hood. The corolla lobes on Emory’s milkweed are less than 1 cm long, which separates this species from both A. oenotheroides and the mojave milkweed (A. nyctaginifolia) (Woodson 1954).

Is this plant invasive?

This plant has not been shown to be invasive, per se, in the literature. However, it has been described as spreading to roadsides (Woodson 1954), a fact that may indicate some invasiveness characteristics.

Gardening with Emory’s Milkweed (Asclepias emoryi)

Vegetative plant of Emory's milkweed (Asclepias emoryi).
Plant of Emory’s Milkweed — Asclepias emoryi (Greene) Tidestr. observed in United States of America by Jo Roberts (licensed under CC BY 4.0)


This species is hardy in zones 7-10. 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 where it can receive full sun and has dry sandy and/or limestone soils.


  • Singhurst, Jason and Ben Hutchins. 2015. Identification of Milkweeds in Texas. Lady Bird Johnson Wildflower Center and Texas Parks and Wildlife.
  • Tidestrom, Ivar. 1935. New Arizona Plant Names. Proceedings of the Biological Society of Washington. 48: 39-44.
  • 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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