prairie ironweed

(Vernonia fasciculata ssp. fasciculata)

Conservation Status
prairie ironweed (ssp. fasciculata)
  IUCN Red List

not listed


NNR - Unranked

SNR - Unranked


not listed

Wetland Indicator Status
  Great Plains

FAC - Facultative


FACW - Facultative wetland

  Northcentral & Northeast

FACW - Facultative wetland


Prairie ironweed (ssp. fasciculata) is a 20 to 55 tall, erect, perennial forb that rises on a single stem or a clump of 2 or more stems from a stout, thickened rootstock.

The stems are erect, round, light green or reddish-purple, and unbranched below the inflorescence. The are usually hairless but are sometimes minutely hairy near the top.

The leaves are alternate, stalkless or on short leaf stalks, narrowly to broadly lance-shaped, 2 to 7 long, and to 1½ wide. The leaf blades are tapered at the base and taper to a sharp point at the tip. The upper surface is green, smooth to the touch, and mostly hairless but may have fine short hairs near the margin. The lower surface is similar in color, hairless, and dotted with minute pitted glands. The glands appear as translucent dots when the leaf is held up to the sun or another light source. The margins are sharply toothed.

The inflorescence is a dense, branched, 1½ to 4 wide, flat-topped cluster (cyme) of many flower heads at the end of the stem. The flower heads within the cyme are not grouped into secondary head-like clusters.

The base of each flower head (involucre) is bell shaped, 3 16 to long and to ¼ high. The involucre is composed of 25 to 35 or more modified leaves (bracts) in 4 or 5 overlapping series. The involucral bracts (phyllaries) are to ¼ long, and their tips are pressed closely to the involucre. They are green but usually tinged purplish along the midvein and toward the tip. They are mostly hairless on the back but sometimes have sparse, long, cobwebby hairs on the margins. The outer phyllaries are broad and scale-like. The inner ones are narrow.

Each flower head has 10 to 26 disk florets and no ray florets. The disk florets are purple and to 7 16 long. They are tube-shaped at the base then separated into 5 long, widely spreading lobes. The flowers have no noticeable scent.

The fruit is a dry, brown, one-seeded, 1 16 to long seed capsule (cypsela) with a modified calyx (pappus) is attached to one end. The pappus is in two series: an outer ring of 20 to 30 minute scales, and an inner tuft of 35 to 45 tan to brownish-purple, 3 16 to ¼ long hair-like bristles.




20 to 55


Flower Color


Reddish purple


Similar Species


Western ironweed (Vernonia fasciculata ssp. corymbosa) is a much shorter plant, reaching only 12 to 24 in height at maturity. The leaves on the main part of the stem are shorter, 1½ to 4 long, wider, and rough to the touch on the upper surface near the margins. In Minnesota it is found only in the western border counties and in the southwest.

Baldwin’s ironweed (Vernonia baldwinii ssp. interior) has hairs on the underside of the leaves that obscure any translucent dots. The tips of the bracts in the involucre curve backward. It has been reported only in Crow Wing (1890) and Goodhue (2000) Counties.


Wet to moderate moisture. Prairies, meadows, pastures, marshes. Full sun.




July to September


Pests and Diseases






Distribution Map












  Kingdom Plantae (green algae and land plants)  
  Subkingdom Viridiplantae (green plants)  
  Infrakingdom Streptophyta (land plants and green algae)  
  Superdivision Embryophyta (land plants)  
  Division Tracheophyta (vascular plants)  
  Subdivision Spermatophytina (seed plants)  
  Class Magnoliopsida (flowering plants)  
  Superorder Asteranae  


Asterales (sunflowers, bellflowers, fanflowers, and allies)  


Asteraceae (sunflowers, daisies, asters, and allies)  
  Subfamily Vernonioideae  
  Tribe Vernonieae  
  Subtribe Vernoniinae  
  Genus Vernonia (ironweeds)  
  Species Vernonia fasciculata (prairie ironweed)  

The tribe Vernonieae was formerly placed in the subfamily Cichorioideae, one of just two subfamilies of Asteraceae. It has been shown that Cichorioideae does not include all of the descendants of a common ancestor and is therefore invalid (paraphyletic). Recent molecular studies of the family Asteraceae proposed several new subfamilies. The Global Compositae Database currently recognizes fifteen subfamilies of Asteraceae, and places the tribe Vernonieae in the subfamily Vernonioideae. The placement has been widely but not universally accepted.


Subordinate Taxa








Common Names


bunched ironweed

common ironweed


prairie ironweed

smooth ironweed













Modified leaf at the base of a flower stalk, flower cluster, or inflorescence.



The group of outer floral leaves (sepals) below the petals, occasionally forming a tube.



A branched, flat-topped or convex flower cluster in which the terminal flower opens first and the outermost flowers open last.



A dry, one-chambered, single-seeded seed capsule, formed from a single carpel, with the seed attached to the membranous outer layer (wall) only by the seed stalk; the wall, formed from the wall of the inferior ovary and also from other tissues derived from the receptacle or hypanthium, does not split open at maturity, but relies on decay or predation to release the contents.



A whorl of bracts beneath or surrounding a flower or flower cluster.



The modified calyx composed of awns, scales, bristles, or feather-like hairs in plants of the Asteraceae family.



An individual bract within the involucre of a plant in the Asteraceae family.

Visitor Photos

Share your photo of this plant.

  This button not working for you?
Simply email us at
Attach one or more photos and, if you like, a caption.






    prairie ironweed (ssp. fasciculata)   prairie ironweed (ssp. fasciculata)  
    prairie ironweed (ssp. fasciculata)      


    prairie ironweed (ssp. fasciculata)   prairie ironweed (ssp. fasciculata)  
    prairie ironweed (ssp. fasciculata)   prairie ironweed (ssp. fasciculata)  


    prairie ironweed (ssp. fasciculata)   prairie ironweed (ssp. fasciculata)  
    prairie ironweed (ssp. fasciculata)      


    prairie ironweed (ssp. fasciculata)   prairie ironweed (ssp. fasciculata)  
    prairie ironweed (ssp. fasciculata)      


    prairie ironweed (ssp. fasciculata)   prairie ironweed (ssp. fasciculata)  






Visitor Videos

Share your video of this plant.

  This button not working for you?
Simply email us at
Attach a video, a YouTube link, or a cloud storage link.


Other Videos



Last Updated:

About Us | Privacy Policy | Contact Us | © All rights reserved.