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A Comprehensive Guide to Woolly Ironweed (Vernonia lindheimeri)

Woolly Ironweed (Vernonia lindheimeri) is a herbaceous perennial that is native to the states of Texas and Arkansas and adjacent areas of Mexico. This plant is a host to the American Lady butterfly (Vanessa virginiensis). Growing from 2 to 3 feet tall, this species grows in calcareous areas, and has pink to purple flowers that bloom from June to August. This plant is hardy in zones 6-10.

Taxonomy and Naming of Woolly Ironweed (Vernonia lindheimeri)

Herbarium specimen of woolly ironweed (Vernonia lindheimeri).
Herbarium Specimen — Vernonia lindheimeri Gray & Engelm. collected in United States of America by The New York Botanical Garden (CC BY 4.0)

Taxonomy

Woolly Ironweed (Vernonia lindheimeri) was named and described by Asa Gray and George Engelmann, both American botanists, in 1848, based on a specimen from New Braunfels, Texas (Wolf 1988). This species has kept the same name since and is a member of the Aster Family (Asteraceae).

Meaning of the Scientific and Common Names

Scientific Name

The genus name, Vernonia, is in honor of William Vernon, an English botanist. The species name, lindheimeri, is in honor of Ferdinand Jacob Lindheimer, a Texas botanist.

Common Name and Alternative Names

The common name comes from the dense tomentose underside of the leaves. Another common name is silver ironweed, likely also in reference the leaf.

Physical Description

Monarch on woolly ironweed (Vernonia lindheimeri) flowers.
Flowers of Woolly Ironweed with Monarch Butterfly — Rhododendrites, CC BY-SA 4.0, via Wikimedia Commons
  • Plant Type: This plant is a herbaceous perennial.
  • Height: This plant is 2 to 3 feet tall.
  • Stem: This plant has multiple ascending stems originating from the base. The stems can be tomentose to canescent (Rydberg and Gleason 1922).
  • Leaves: The leaves are alternate, short-petiolate, simple, entire, and linear in shape with revolute margins. The leaves are 1-4 inches in length and 0.05-0.1 inches in width. The leaves are densely tomentose or white-woolly underneath (Rydberg and Gleason 1922).
  • Flower color: pink to purple
  • Blooming period: This plant blooms from June to August.
  • Fruiting type and period: This plant has achenes that mature in the late summer to fall.

Range of Woolly Ironweed (Vernonia lindheimeri) in the United States and Canada

Range map of woolly ironweed (Vernonia lindhemieri) 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 ironweed is native to the states of Texas and Arkansas and adjacent areas of Mexico.

Habitat

River Floodplain habitat
River Floodplain Habitat — Leonhard Lenz, CC0, via Wikimedia Commons

This species grows in open calcareous areas such as dry rocky limestone (Singhurst, et al 2010), pebbly river beds (Gray and Wright 1852), riparian areas (Whisnant 1981), and prairies (Gleason 1906).

Hosted Insects

American lady butterfly on white flower.
American Lady Butterfly (Vanessa virginiensis) — ALAN SCHMIERER, CC0, via Wikimedia Commons

This species is a host for the American Lady Butterfly (Vanessa virginiensis).

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. Birds, such as goldfinch, like to eat the seeds in the fall.

Frequently Asked Questions

Does this plant have any ethnobotanical uses?

The Native American Ethobotanical Database does not cite this species specifically, but ironweeds in general, have been used as anti-diarrheal drug.

How is this plant distinguished from other Ironweeds?

The lack of basal leaves and the white-woolly pubescence on the underside of the leaves serves to distinguish this species from other ironweeds.

Is this plant invasive?

This plant has not been noted as being invasive in the literature. Generally this plant has a restricted habitat in areas of high pH soil. The Texas Native Plant Society says that this plant does reproduce aggressively like other members of the genus.

Is this plant deer resistant?

This plant has been noted as being deer resistant by Gardenia.net.

Gardening with Woolly Ironweed (Vernonia lindheimeri)

Add Woolly Ironweed to Your Garden

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Plant of woolly ironweed (Vernonia lindheimeri).
Woolly Ironweed (Vernonia lindheimeri) — Mason Brock (Masebrock), Public domain, via Wikimedia Commons

Hardiness

This species is hardy in zones 6-10. 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 in places with full sun to partial-shade and in soils having a high pH. It is also tolerate of drought and can handle dry conditions.

Additional Notes about this Plant

This ironweed is a suggested plant for xeriscaping because of its drought resistance.

References

  • Gleason, Henry A. 1906. A Revision of the North American Veronicae. Bulletin of the New York Botanical Garden 4(13): 144-243.
  • Gray, Asa and Charles Wright. 1852. Plantae Wrightianae texano-neo-mexicanae: an account of a collection of plants made by Charles Wright. (Washington, DC: Smithsonian Institution).
  • Rydberg, Per Axel and Henry Gleason. 1922. North American Flora 33: pt. 1.
  • Singhurst, Jason R., Laura L. Hansen, Jeffrey N. Mink, Bill Armstrong, Donnie Frels, and Walter C. Holmes. 2010. The Vascular Flora of Kerr Wildlife Management Area, Kerr County, Texas. Journal of the Botanical Research Institute of Texas 4: 497-521.
  • Weakley, A.S., and Southeastern Flora Team 2022. Flora of the southeastern United States. University of North Carolina Herbarium, North Carolina Botanical Garden.
  • Whisnant, S.G. 1981. The Vascular Flora of McCulloch County, Texas. The Texas Journal of Science 33: 197-220.
  • Wolf, Steven J. 1988. George Engelmann Type Specimens in the Herbarium of the Missouri Botanical Garden. Annals of the Missouri Botanical Garden 75: 1608-1636.
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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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