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A Comprehensive Guide to Nodding Milkweed (Asclepias glaucescens)

Nodding Milkweed (Asclepias glaucescens) is a herbaceous perennial that is native to the states of Texas, New Mexico, and Arizona in the United States. This plant is a host to the Queen (Danaus gilippus) and Monarch (Danaus plexippus) butterflies. Growing from 0.5 to 4 feet tall, this species has white to green flowers that bloom from April to August. It is hardy in zones 7-11.

Taxonomy and Naming of Nodding Milkweed (Asclepias glaucescens)

Herbarium specimen of nodding milkweed (Asclepias glaucescens).
Herbarium Specimen — Asclepias glaucescens Kunth collected in Mexico by The New York Botanical Garden (licensed under CC BY 4.0)

Taxonomy

Nodding Milkweed (Asclepias glaucescens) was originally named and described by Carl Sigismund Kunth, a German botanist, in 1819. Since this time, several other names for this plant have been proposed, but it has kept the same name. This species 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, glaucescens, is Latin for white.

Common Name and Alternative Names

The common name comes from white color (glaucous) of the stems. There are many Spanish and local tribal common names for this plant including matacoyote, jicaca, and oreja de burro (Standley, et al. 1969).

Physical Description of Nodding Milkweed (Asclepias glaucescens)

Cluster of pinkish flowers of nodding milkweed (Asclepias glaucescens).
Flowers of Nodding Milkweed (Asclepias glaucescens) — Edgar p miller, CC BY-SA 4.0, via Wikimedia Commons

Description

  • Plant Type: This plant is a herbaceous perennial
  • Height: 0.5 to 4 feet
  • Stem: The stem is ascending and glaucous (Woodson 1954).
  • Leaves: The leaves are opposite, sessile, simple, entire, and ovate to oval in shape. The leaves are 2 to 7 inches long and about 0.4 to 3 inches wide. The leaves are somewhat succulent (Woodson 1954).
  • Flower color: white to greenish-cream with hints of red or purple
  • Blooming period: This plant blooms from June to September (Singhurst and Hutchins 2015).
  • Fruiting type and period: This plant has follicles that mature in the late summer and fall.

Range of Nodding Milkweed (Asclepias glaucescens) in the United States and Canada

Range map of nodding milkweed (Asclepias glaucescens) 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 states of Texas, New Mexico, and Arizona and Mexico south to Costa Rica.

Habitat

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

This species grows in dry woodlands, rocky slopes, creek beds, and old fields where there is disturbance.

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 Nodding Milkweed (Asclepias glaucescens)

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 both tufted milkweed (Asclepias nummularia), sand milkweed (Asclepias arenaria), and broad-leaf milkweed (Asclepias latifolia). It differs from the tufted milkweed by having a taller stem (5 cm vs. 20 cm +). It differs from the sand milkweed and broad-leaf milkweed in having thin leaves, whereas the other two have thick leaves (Wooton 1915).

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.

Gardening with Nodding Milkweed (Asclepias glaucescens)

Plant of nodding milkweed (Asclepias glaucescens) with white flowers.
Nodding Milkweed (Asclepias glaucescens) — Bodofzt, CC BY-SA 4.0, via Wikimedia Commons

Hardiness

This species is hardy in zones 7-11. 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 soil.

References

  • Singhurst, Jason and Ben Hutchins. 2015. Identification of Milkweeds in Texas. Lady Bird Johnson Wildflower Center and Texas Parks and Wildlife.
  • Standley, Paul Carpenter, Louis O. Williams, and Dorothy N. Gibson. 1969. Flora of Guatemala. (Chicago, IL: Field Museum of Natural History).
  • Woodson, Robert E. 1954. The North American Species of Asclepias L. Annals of the Missouri Botanical Garden 41: 1-211.
  • Wooten, E.O. and Paul C. Standley. 1915. Flora of New Mexico. Contributions from the United States National Herbarium v. 19.
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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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