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A Comprehensive Guide to Prairie Ironweed (Vernonia fasciculata)

Prairie Ironweed (Vernonia fasciculata) is a herbaceous perennial that is native to the midwestern and Great Plains of the United States and the province of Manitoba. This plant is a host to the American Lady butterfly (Vanessa virginiensis). Growing from 2 to 4 feet tall, this species grows in moist prairies and has pink to purple flowers that bloom from July to September. This plant is hardy in zones 4-9.

Taxonomy and Naming of Prairie Ironweed (Vernonia fasciculata)

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

Taxonomy

Prairie Ironweed (Vernonia fasciculata) was named and described by Andre Michaux, a French botanist, in 1803. 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, fasciculata, derives from fascicle, meaning a bundle.

Common Name and Alternative Names

The common name derives from the common habitat of this species. Other common names include smooth ironweed for the glabrous leaves, western ironweed (Moldenke 1943), and common ironweed.

Physical Description of Prairie Ironweed (Vernonia fasciculata)

Plants of prairie ironweed (Vernonia fasciculata) in a field.
Plants of Prairie Ironweeed — Public Domain from Wikimedia Commons (EPA)

Description

  • Plant Type: This plant is a herbaceous perennial.
  • Height: This plant is 2 to 4 (6) feet tall. It will grow taller in moist soil (Missouri Botanical Garden).
  • Stem: The stems are ascending and are green to purple in color. This plant spreads via rhizomes. The stem is generally smooth (Il Natural History Survey 1936).
  • Leaves: The leaves are alternate, sessile to short-petiolate, simple, have toothed margins, and lanceolate-ovate to linear in shape. The leaves are 4-7 inches in length and 0.5-2 inches in width. The leaves have a rough texture (Missouri Botanical Garden).
  • Flower color: Magenta to purple
  • Blooming period: This plant blooms from May to September.
  • Fruiting type and period: This plant has achenes that mature in the late summer to fall.

Range of Prairie Ironweed (Vernonia fasciculata) in the United States and Canada

Range map of prairie ironweed (Vernonia fasciculata) 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 generally to the mid-west and Great Plains of the United States and the province of Manitoba in Canada. It is considered to be rare in a lot of the jurisdictions in which it occurs, including Texas, Montana, Colorado, Kentucky, Ohio, Michigan, and the province of Manitoba. This species is considered to be adventive in the states of New York and Massachusetts (Eaton 1936).

Habitat

Prairie in Ohio
Moist Prairie Habitat — Sixflashphoto, CC BY-SA 4.0, via Wikimedia Commons

This species grows in moist prairies (White and Johnson 1980 and Il Natural History Survey 1936), low wet ground (Hayden 1919 and Gleason 1904), fen margins (Nekola 1994), bottomland forests (Keammerer, et al 1975), pastures (Bessey 1871 and Braun 1916), river meadows (Wheeler 1900), and marshy meadows (Somes 1913).

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). Some moths also feed on this species including the Parthenice Tiger Moth (Grammia parthenice) and the Red Groundling (Perigea xanthoides) (Illinois Wildflowers). The Ironweed Aphis (Aphis vernoniae) has been noted as a pest on this species (Thomas 1878).

Other Supported Wildlife

Honeybee on purple flower.
Purple Aster with Honeybee — John Severns (Severnjc), Public domain, via Wikimedia Commons

This species is a nectar source to other butterflies, skippers, bees, and wasps during the growing season. The Diana Fritillary (Speyeria diana) has been noted especially as using this species as a nectar plant (Edwards 1868) and also long-horned bees (Melissodes vernoniae) (LaBerge 1961). Birds, such as goldfinch, like to eat the seeds in the fall.

Frequently Asked Questions about Prairie Ironweed (Vernonia fasciculata)

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 fairly unique among the ironweeds in that it has glabrous (hairless) leaves and a compact inflorescence. The leaves have been described as conspicuously punctate beneath (Wunderlin 1968).

Is this plant invasive?

This plant has been noted as being a weed in Iowa (Bessey 1871 and Pammel et al 1913), but it has not been noted as being a weed in other places.

Is this plant deer resistant?

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

Gardening with Prairie Ironweed (Vernonia fasciculata)

Add Prairie Ironweed to Your Garden

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Plant of prairie ironweed (Vernonia fasciculata) with flowers and seed heads.
Prairie Ironweed (Vernonia fasciculata) — Krzysztof Ziarnek, Kenraiz, CC BY-SA 4.0, via Wikimedia Commons

Hardiness

This species is hardy in zones 4-9. 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. However, this is a rare species and is not in the horticultural trade.

Optimal Conditions

This species can grow in full sun in medium to moist soil. In a garden this species can handle drier conditions and partial-sun.

Additional Notes about this Plant

Prairie Ironweed is a suggested plant for areas of full sun exposure on golf courses (Voigt 2000).

References

  • Bessey, Charles E. 1871. Contributions to the flora of Iowa. (Ames, IA: IA Agricultural College).
  • Braun, E.L. 1916. The physiographic ecology of the Cincinnati Region. Bulletin of the Ohio Biological Survey 7: 113-211.
  • Eaton, Richard J. 1936. Some Adventitious Plants in Concord, Massachusetts. Rhodora 38: 64-67.
  • Edwards, William H. 1868. The Butterflies of North America. (Philadelphia: American Entomological Society).
  • Gleason, Henry A. 1904. The vegetation of the Ozark region in southern Illinois. M.A. Thesis, University of Illinois.
  • Hayden, Ada. 1919. The ecologic anatomy of some plants of a prairie province in central Iowa. Ph.D Dissertation at Iowa State University.
  • Illinois Natural History Survey. 1936. Illinois Wild Flowers. Illinois Natural History Survey Manual 1.
  • Keammerer, Warren R., W. Carter Johnson, and Robert L. Burgess. 1975. Floristic Analysis of the Missouri River bottomland forests in North Dakota. Canadian Field-Naturalist 89(1): 5-19.
  • LaBerge, Wallace E. 1961. A Revision of the Bees of the Genus Melissodes in North and Central America. Part III (Hymenoptera, Apidae). The University of Kansas Science Bulletin 42: 283-663.
  • Moldenke, Harold N. 1943. The flora of the North Appalachian Experimental Watershed and surrounding territory. (Conshocton, OH: USDA Soil Conservation Service).
  • Nekola, J.C. 1994. The Environment and Vascular Flora of Northeastern Iowa Fen Communities. Rhodora 96: 121-169.
  • Pammel, L.H., Charlotte Maria King, and John N. Martin. 1913. The weed flora of Iowa. Iowa Geological Survey Bulletin No. 4.
  • Somes, M.P. 1913. Notes on the Flora of Johnson County, Iowa. The Proceedings of the Iowa Academy of Science 20: 27-102.
  • Thomas, Cyrus. 1878. Noxious and Beneficial Insects of the State of Illinois. Eighth Report of the State Entomologist.
  • Voigt, Tom. 2000. Native Midwestern Plants for Golf Course Landscapes. Erigenia 18: 58-65.
  • Weakley, A.S., and Southeastern Flora Team 2022. Flora of the southeastern United States. University of North Carolina Herbarium, North Carolina Botanical Garden.
  • Wheeler, W.A. 1900. XXII. A Contribution to the Knowledge of the Flora of Southeastern Minnesota. Minnesota Botanical Studies Second Series Part IV 353-416.
  • White, David J. and Karen Johnson. 1980. The Rare Vascular Plants of Manitoba. Syllogeus 27.
  • Winderlin, R.P. 1968. Contributions to an Illinois Flora No. 2 Compositae I. (Tribe Vernonieae). Transactions of the Illinois Academy of Science 61: 132-138.
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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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