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Arizona Milkweed (Asclepias angustifolia), a Comprehensive Guide in 10 Sections

Introduction

Arizona Milkweed (Asclepias angustifolia) is a herbaceous perennial that is native to the state of Arizona. This milkweed is a host plant to the Monarch Butterfly and a nectar plant to others. It can grow up to 3 feet tall and has linear shaped leaves. The white with pink or purple tinged flowers bloom from June to July. It is grows between 3,500 ft and 7,000 ft of elevation and is hardy in zones 6-10. The seeds for this plant can be purchased in the McMullen House Bed & Breakfast Garden Shop.

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Taxonomy and Naming of Arizona Milkweed (Asclepias angustifolia)

Herbarium specimen of Arizona Milkweed (Asclepias angustifolia).
Arizona Milkweed — Asclepias angustifolia Sessé & Moc. by The New York Botanical Garden (licensed under CC BY 4.0)

Taxonomy

Arizona Milkweed (Asclepias angustifolia) was named and described by August Friedrich Schweigger, a German naturalist, in 1812. The description was based on a plant then growing at the Konigsberg Botanical Garden in Germany (Stevens 2005). It has kept the same name since. This plant 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, angustifolia, means narrow in Latin and refers to the linear leaves.

Common Name and Alternative Names

The common name for this plant is in reference to the location of the plant. Other alternative names such as narrow-leaved milkweed and slender milkweed refer to the leaf shape. One alternative, Talayote, is a Spanish name for the species.

Physical Description of Arizona Milkweed (Asclepias angustifolia)

White flowers of Arizona Milkweed (Asclepias angustifolia) in a field.
White flowers of Arizona Milkweed — Pamahon, CC BY-SA 4.0, via Wikimedia Commons

Description

  • Plant Type: Herbaceous perennial to somewhat suffrutescent (Woodson 1954)
  • Height: up to 3 feet
  • Leaves: Leaves are opposite, simple, entire, linear to lanceolate leaves and are 1.5 to 5 inches in length and 0.1 to 0.5 inches in width. The leaves are nearly sessile to the stem and are often paired.
  • Flower color: white with a tinge of pink or purple
  • Blooming period: June to July, but can flower throughout the year (Woodson 1954)
  • Fruit type and period: follicle/pod that matures in the late summer to fall

Range Map of Arizona Milkweed (Asclepias angustifolia) in the United States and Canada

Range Map of Arizona Milkweed (Asclepias angustifolia) in the United States and Canada.

This species is native to Arizona and south into Mexico. This species is endemic to the state of Arizona in the United States.

Habitat

Desert habitat with sand in the southwestern United States.
Desert Habitat with Sand — Patrick Alexander from Las Cruces, NM, CC0, via Wikimedia Commons

This species grows in dry woodlands, floodplains (creek bottoms and canyons), prairies, meadows, and roadsides with sandy or gravelly soil. It is often found between 3,500 and 7,000 feet of elevation.

Hosted Insects

Monarch butterfly (Danaus gilippus) on a green flower.
Monarch Butterfly on a green flower — U.S. Fish and Wildlife Service, Public domain, via Wikimedia

This milkweed, like a lot of milkweeds, is a host to the Monarch Butterfly (Danaus plexippus). It is also a host to the Queen butterfly (Danaus gilippus).

Other Supported Wildlife

Bumblebee on a pink flower.
Bumblebee on a pink flower — Weerlicht, CC0, via Wikimedia Commons

This milkweed, like a lot of other milkweeds, is a nectar source to other species, especially carpenter bees (Wikipedia).

Frequently Asked Questions about Arizona Milkweed (Asclepias angustifolia)

What other milkweeds are similar to this one?

This plant looks similar to Texas milkweed (Asclepias texana). However, Arizona milkweed is endemic to Arizona and has linear to narrowly-lanceolate leaves and Texas milkweed has oval to oblong leaves that are shorter at about 3 inches long (Sundell 1990). Horsetail milkweed (Asclepias subverticillata) and whorled milkweed (Asclepias verticillata) are also similar, but they both have whorled leaves, rather than opposite leaves (Southeastern Arizona Wildflowers and Plants).

Is this plant poisonous to pets?

This plant, being a milkweed, contains cardiac cardenolides, which are poisonous when ingested. The American Society for the Prevention of Cruelty to Animals (ASPCA, link to page) lists milkweeds are being poisonous. The monarch butterfly uses these compounds to make itself unpalatable to predators.

Gardening with Arizona Milkweed (Asclepias angustifolia)

Plants of Arizona Milkweed (Asclepias angustifolia).
Plant of Arizona Milkweed — Pamahon, CC BY-SA 4.0, via Wikimedia Commons

Hardiness

This species is hardy in zones 7 to 10. If your garden is located within these zones is likely you can grow this plant if you have the right growing conditions such as moisture and soil. The hosted species, the monarch butterfly, is wide ranging and likely in your area.

Cultivars

Optimal Conditions

This milkweed prefers places with partial shade, such as under a tree, but can grow in full sun. It can handle temperatures into the teens and needs a moderate amount of water. Rock gardens are suitable for this plant.

References

  • Stevens, W.D. 2005. New and Interesting Milkweeds (Apocynaceae, Asclepiadoideae). Novon 15: 602-619.
  • Sundell, Eric. 1990. Notes on Arizona Asclepias (Asclepiadaceae) with a new combination. Phytologia 69:265-270.
  • 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 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 for Silphium Design LLC.

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