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A Comprehensive Guide to Prostrate Milkweed (Asclepias prostrata)

Prostrate Milkweed (Asclepias prostrata) is a herbaceous perennial that is native to the state of Texas in the United States. This plant is a host to the Queen (Danaus gilippus) and Monarch (Danaus plexippus) butterflies. Growing from 0.5 to 1.5 feet tall, this species has greenish-white to rose colored flowers that bloom from April to October. It is hardy in zones 8-10.

Taxonomy and Naming of Prostrate Milkweed (Asclepias prostata)

Herbarium specimen of prostrate milkweed (Asclepias prostrata).
Herbarium Specimen of Prostrate Milkweed (Asclepias prostrata) — Harvard University, Public Domain

Taxonomy

Prostrate Milkweed (Asclepias prostrata) was originally named and described by Will H. Blackwell, an American botanist, in 1964, based on a specimen in Mexico (Blackwell 1964). This species still uses this name 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, prostrata, is Latin for prostrate and describes the prostrate habit of the plant.

Common Name and Alternative Names

The common name comes from the prostrate growing habit of the plant.

Physical Description of Prostrate Milkweed (Asclepias prostrata)

Yellowish-white flowers of prostrate milkweed (Asclepias prostrata).
Flowers of Prostrate Milkweed — Sam Kieschnick, CC BY 4.0, via Wikimedia Commons

Description

  • Plant Type: This plant is a herbaceous perennial
  • Height: 1 to 1.5 feet
  • Stem: The stem has a prostrate habit, hence the name of the plant.
  • Leaves: The leaves are opposite, short-petiolate, wavy margined and triangular shaped (Singhurst and Hutchins 2015). They range from 0.6 to 1.5 inches long and 0.2 to 0.8 inches wide.
  • Flower color: greenish-white to rose (Singhurst and Hutchins 2015)
  • Blooming period: This plant blooms from April to October.
  • Fruiting type and period: This plant has follicles that mature in the late summer and fall.

Range of Prostrate Milkweed (Asclepias prostrata) in the United States and Canada

Range of prostrate milkweed (Asclepias prostrata) 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 native to the state of Texas in the United States and to Mexico.

Habitat

Desert Shrub Habitat
Desert Shrub — Patrick Alexander from Las Cruces, NM, CC0, via Wikimedia Commons

This species grows in shrublands with sandy soil.

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 Prostrate Milkweed (Asclepias prostrata)

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 pharmaceuticals, foods, and fibers.

How is this plant distinguished from other milkweeds?

The prostrate habit of this plant readily identifies it (Singhurst, et al 2015).

Is this plant invasive?

This plant is rare and not considered to be invasive.

Gardening with Prostrate Milkweed (Asclepias prostrata)

Plant of prostrate milkweed (Asclepias prostrata) in a desert.
Plant of Prostrate Milkweed — Asclepias prostrata W.H.Blackw. observed in United States of America by David Peden (licensed under CC0 1.0)

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 where there is a lot of moisture and gets full to partial sun.

Additional Notes about this Plant

This species of milkweed is rare and is not cultivation.

References

  • Blackwell, Will H. 1964. Synopsis of the 23 Species of Asclepias (Asclepiadaceae) inTamaulipas and Nuevo Leon Including Two New Species, Asclepias bifida and Asclepias prostrata. The Southwestern Naturalist 9(3): 171-180.
  • Singhurst, Jason, Ben Hutchins, and Walter Holmes. 2015. Identification of Milkweeds of Texas. Texas Parks and Wildlife Department.
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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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