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Western Sand Milkweed (Asclepias arenaria), a Comprehensive Guide in 9 Sections

Western Sand Milkweed (Asclepias arenaria) is a herbaceous perennial that grows in sandy open places that are dry and have full sun. It is a host plant for the Monarch Butterfly and a nectar plant for other insects. The greenish-white flowers bloom from the late spring to early fall. This plant is natively located in the Great Plains region of the United States.

Taxonomy and History of Western Sand Milkweed (Asclepias arenaria)

Herbarium specimen of western sand milkweed (Asclepias arenaria).
Herbarium Specimen of Western Sand Milkweed (Asclepias arenaria) — CC0 1.0 Universal (CC0 1.0) Public Domain Dedication from Texas Tech Herbarium, E.L. Reed Herbarium

Taxonomy

Western Sand Milkweed (Asclepias arenaria) was originally described by John Torrey, an American botanist, in 1859 (Torrey 1859). The decription is based on a specimen from the state of New Mexico (GBIF) from the Jornada del Muerto region (Standley 1909), a sandy plant to the east of the Rio Grande River. The plant is thought to be collected by a botanist named Wislizenus in 1846 (Woodson 1954) and was listed as growing on “sandy banks” (Standley 1909). This plant is a member of the Dogbane Family (Apocynaceae).

Meaning of the Scientific and Common Names

Scientific Name

The genus name, Asclepias, refers to the Greek god of medicine and the species name, arenaria, means “of sand.” (Kansas Wildflowers and Grasses)

Common Name and Alternative Names

The common name, Western Sand Milkweed, refers to the location and habitat of the species. Other names used generally refer to the habitat are shortened to “Sand Milkweed.”

Physical Description of Western Sand Milkweed (Asclepias arenaria)

White flowers of western sand milkweed (Asclepias arenaria).
Flowers of Western Sand Milkweed — Asclepias arenaria Torr. observed in United States of America by Michelle (licensed under CC BY 4.0)

Description

  • Plant Type: Herbaceous perennial
  • Height: up to about 3 feet tall
  • Leaves: opposite, obovate-oval, simple, entire that range from 2-4 inches in length and 1-3 inches in width. The leaves are white-tomentose beneath.
  • Stem: simple pubescent stem that contains milky sap that is typical of milkweeds. Stems can have a declining habit.
  • Flower color: pale green to greenish-white, hoods are a pale purple color
  • Blooming period: May to October
  • Fruiting type and period: follicles that mature in the fall

Range of Western Sand Milkweed (Asclepias arenaria) in the United States

Range map of western sand milkweed (Asclepias arenaria) in the United States and Canada.

This species is centered in the Great Plains of the midwestern United States. It is considered to be rare in the state of Wyoming. It also extends into northern Mexico.

Habitat of Western Sand Milkweed (Asclepias arenaria)

Sandy Habitat in southwestern US.
Sandy Habitat — “Sevilleta National Wildlife Refuge” by aspidoscelis is marked with CC0 1.0.

This plant grows in sandy open places such as fields, pastures, dunes, sandhills, and roadsides that have full sun. This plant is very drought tolerant and can handle dry conditions. It is often a component of the Nebraska (Weaver 1920) and Kansas (Hitchcock 1898) sandhills in mixed-prairie vegetation (Weaver 1920).

Hosted Insects

Monarch butterfly on butterfly weed (Asclepias tuberosa).
Butterfly Weed with Monarch Butterfly — Laura Perlick, U.S. Fish and Wildlife Service, Public domain, via Wikimedia Commons

This plant is a host to the Monarch butterfly (Danaus plexippus).

Other Supported Wildlife

House sparrow on log.
House Sparrow — Mathias Appel, CC0 1.0, via Wikimedia Commons

The flowers are used as a nectar source by other butterflies, bees, and insects and the fruits a food source for birds.

Gardening with Western Sand Milkweed (Asclepias arenaria)

Plant of western sand milkweed (Asclepias arenaria).
Plant of Western Sand Milkweed — “Broadleaf Milkweed” by Coastlander is licensed under CC BY 2.0.

Hardiness

Western Sand Milkweed is hardy in zones 4a to 9b. If your garden is within these you may be able to possibly grow it in your area. This plant is generally restricted to sandy habitats in the Great Plains and deserts and may not do as well in the Eastern United States. However, the main host of milkweeds, the monarch butterfly is present in both areas.

Optimal Conditions for Growing

Sandy well-drained soil in full sun. These plants are deer and rabbit resistant due to the poisonous sap contained in the plant.

Interesting to Know

This plant smells like a bacon-cheeseburger and is diagnostic of the plant (Singhurst, Jason, et al. Identification of Milkweeds in Texas (PDF). Lady Bird Johnson Wildflower Center). The genus name, Asclepias, refers to the Greek god of medicine and the species name, arenaria, means “of sand.” (Kansas Wildflowers and Grasses)

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References

  • Hitchcock, A.S. 1898. Ecological Plant Geography of Kansas. Transactions of the Academy of Science of St. Louis. 8: 55-69.
  • Standley, Paul C. 1909. The type localities of plants first described from New Mexico. Contributions from the US National Herbarium 13: 142-227.
  • Torrey, John. 1859. Report on the United States and Mexican Boundary survey: made under the direction of the secretary of the Interior. Washington, DC: US Department of the Interior. V. II
  • Weaver, John E. 1920. A correlation of the root systems of native vegetation and crop plants. Washington, DC: Carnegie Institute of Washington. Publication 292.
  • Woodson, Robert E. 1954. The North American Species of Asclepias L. Annals of the Missouri Botanical Garden 41: 1-211.

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