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A Comprehensive Guide to Western Ironweed (Vernonia baldwinii)

Western Ironweed (Vernonia baldwinii) is a herbaceous perennial that is native to the midwestern United States. This plant is a host to the American Lady butterfly (Vanessa virginiensis). Growing from 2 to 5 feet tall, this species grows in prairies, forest openings, fields, and pastures. It has pink to purple flowers that bloom from May to September and is hardy in zones 5-9.

Taxonomy and Naming of Western Ironweed (Vernonia baldwinii)

Herbarium specimen of western ironweed (Vernonia baldwinii).
Herbarium Specimen — Vernonia baldwinii Torr. collected in United States of America by The New York Botanical Garden (licensed under CC BY 4.0)


Western Ironweed (Vernonia baldwinii) was named and described by John Torrey, an American botanist, in 1828. 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, baldwinii, is in honor of William Baldwin, who originally collected the plant and was an American botanist and physician (Wikipedia).

Common Name and Alternative Names

The common name derives from the native locality of the plant at the time it was collected. Another common name, Baldwin’s ironweed, comes from the species name.

Physical Description of Western Ironweed (Vernonia baldwinii)

Plant of western ironweed (Vernonia baldwinii) with purple flowers.
Plant of Western Ironweed — “Vernonia baldwinii” by Dr. Alison Northup is licensed under CC BY 4.0.


  • Plant Type: This plant is a herbaceous perennial.
  • Height: This plant is 2 to 6 feet tall. It will grow taller in moist soil (Missouri Botanical Garden).
  • Stem: The stems are ascending and tomentose. This plant spreads via rhizomes.
  • Leaves: The leaves are alternate, simple, have serrate margins, and lanceolate-ovate in shape. The leaves are 4-7 inches in length and 1-2 inches in width. The leaves have a rough texture (Missouri Botanical Garden).
  • Flower color: pink, red-purple (Young 1920) to purple
  • Blooming period: This plant blooms from May to September. This is among the first of the ironweeds to flower (Sargent 1891).
  • Fruiting type and period: This plant has achenes that mature in the late summer to fall.

Range of Western Ironweed (Vernonia baldwinii) in the United States and Canada

Range map of Western Ironweed (Vernonia baldwinii) in the United States and Canada.
Range Map Credit: Kartesz, J.T., The Biota of North America Program (BONAP). 2023.(website 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)]

Western ironweed is located in the midwestern United States.


Meadow habitat in Europe.
Meadow Habitat — Leonhard Lenz, CC BY-SA 4.0, via Wikimedia Commons

This species grows in open areas such as fields, railroads, pastures, prairies, floodplains (Young 1920 and Hitchcock 1898), moist soils along banks of creeks and rivers (Hansen 2010), and forest openings.

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. In the mountains of Arkansas, this plant has been noted as a nectar plant for the Monarch Butterfly (Rudolph, et al 2006). Birds, such as goldfinch, like to eat the seeds in the fall.

Frequently Asked Questions about Western Ironweed (Vernonia baldwinii)

Is this plant poisonous?

This plant is not listed as being poisonous, but it has been noted to cause contact dermatitis (Rodriguez et al 1977).

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?

This species is similar to the Missouri ironweed (Vernonia missourica). However, Missouri ironweed has more florets (30-55) per flowering head than this species, which has about 15-35 florets (Weakley 2022). This species is also similar to prairie ironweed (Vernonia fascicularis), however prairie ironweed has involucral bracts with appressed tips, while Baldwin’s ironweed has recurved or spreading tips (Peterson 1923). The leaves are also glabrous in prairie ironweed and tomentose in this species (Britton and Brown 1913). It can be separated from plains ironweed (Vernonia marginata), which has linear leaves, by its lanceolate leaves (Peterson 1923).

Is this plant invasive?

While this plant has been noted to be in disturbed areas and is included in a weed book (Reed 1971), these sources do not note it as invasive. It is probably included because of being in disturbance places.

Is this plant deer resistant?

This plant has been noted as being deer resistant by

Gardening with Western Ironweed (Vernonia baldwinii)

Add Western Ironweed to Your Garden

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Purple flowers of western ironweed (Vernonia baldwinii).
Flowers of Western Ironweed — “Vernonia baldwinii” by Dr. Alison Northup is licensed under CC BY 4.0.


Western ironweed is hardy roughly in zones 5-9. 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 can grow in full sun to partial sun in well-drained soil. This species is considered to be more drought resistant than other ironweeds (Illinois Wildflowers).


  • Britton, Nathaniel Lord and Addison Brown. 1913. An illustrated flora of the northern United States, Canada, and the British possessions: from Newfoundland to the parallel of the southern boundary of Virginia, and from the Atlantic Ocean westward to the 102nd meridian. (New York: Scribner’s Sons).
  • Hansen, Laura L. 2010. Annotated Checklist of the Vascular Plants of Fort Hood, Texas. Journal of The Botanical Research Institute of Texas 4: 523-558.
  • Hitchcock, A.S. 1898. Ecological Plant Geography of Kansas. Transactions of the Academy of Science of St. Louis 8: 55-69.
  • Peterson, Niels Frederick. 1923. Flora of Nebraska; a list of the ferns, conifers, and flowering plants of the state with keys for their determination. (Plainview, NE: self-published).
  • Reed, Clyde Franklin. 1971. Common Weeds of the United States. (New York: Dover Publications) USDA Agricultural Research Service.
  • Rodriguez, Eloy, GHN Towers, and John C. Mitchell. 1977. Allergic Contact Dermatitis and Sesquiterpene Lactones. Compositae Newsletter 4: 4-10.
  • Rudolph, D. Craig, Charles A. Ely, Richard R. Schaefer, J. Howard Williamson, and Ronald E. Thill. 2006. Monarch (Danaus plexippus L. Nymphalidae) Migration, Nectar Resources and Fire Regimes in the Ouachita Mountains of Arkansas. Journal of the Lepidopterists Society 60(3): 165-170.
  • Sargent, Charles Sprague. 1891. Garden and forest; a journal of horticulture, landscape art and forestry. v. 4.
  • Weakley, A.S., and Southeastern Flora Team 2022. Flora of the southeastern United States. University of North Carolina Herbarium, North Carolina Botanical Garden.
  • Young, Mary Sophie. 1920. The seed plants, ferns, and fern allies of the Austin Region. University of Texas bulletin no. 2065.
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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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