prairie ironweed

(Vernonia fasciculata ssp. fasciculata)

               
Conservation Status

IUCN Red List

not yet assessed

prairie ironweed (ssp. fasciculata)

NatureServe

NNR - Unranked

SNR - Unranked

Minnesota

not listed

Wetland
Indicator
Status

Great Plains

FAC - Facultative

Midwest

FACW - Facultative wetland

Northcentral & Northeast

FACW - Facultative wetland

Nativity

Native

 
Occurrence

Common

 
Habitat

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

 
Flowering

July to September

     
Flower Color

Reddish purple

     
Height

20 to 55

     

Identification

This 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.

 
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 (in1890) and Goodhue (in 2000) Counties.


Distribution Distribution Map   Sources: 7.

Comments

 


Taxonomy

Family:

Asteraceae (aster)

 

Subfamily:

Cichorioideae

 

Tribe:

Vernonieae (ironweed)

 

Subtribe:

Vernoniinae

 
Parent

prairie ironweed (Vernonia fasciculata)

 
Synonyms

 

 
Common
Names

bunched ironweed

common ironweed

ironweed

prairie ironweed

smooth ironweed


 

 

 

 

 

 

 

 

 

Glossary

bract

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

 

calyx

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

 

cyme

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

 

cypsela

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.

 

involucre

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

 

pappus

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

 

phyllary

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

       

Visitor Photos

   
Share your photo of this plant.

       
       
       
       

MinnesotaSeasons.com Photos

   

Plant

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

Inflorescence

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

Flowers

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

Leaves

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

Stem

  prairie ironweed (ssp. fasciculata)   prairie ironweed
       
       

 

Camera

     

Slideshows

   
     
     
     

 

slideshow

     

Visitor Videos

   
Share your video of this plant.

     
     

Other Videos

 
     
     
     
     

 

Camcorder

Last Updated:

About Us | Privacy Policy | Contact Us | © 2017 MinnesotaSeasons.com. All rights reserved.