The Medicinal Plant Garden

of Birmingham-Southern College

  • Vernonia gigantea
  • Vernonia gigantea

Common Name

Iron weed, giant ironweed, tall ironweed, blue vervain, and Indian-hyssop

Related Species

V. altissima, V. fasciculata, V. flaccidifolia (Crelin and Philpott, 1990).

Geographic Distribution and Habitat

As a native species of North America, Vernonia gigantea is one of over 1000 species of Vernonia, with 18 growing in the Eastern United States, and many in Africa and South America (Urbatsch, 1991). V. gigantea typically grows in the areas from Maine, down the Eastern coast of the United States to Florida and across the Southeastern United States to Texas (Burgess, 2011).  Bryson and DeFelice (2009) report that V. gigantea grows along roadsides, in pastures, and near marshy woodland areas.


V. gigantea can grown up to anywhere from 7-9 feet in height (Dole, 2003). The leaves alternate along the stem and are anywhere from 6-30 cm long and 1-4 cm wide (Bryson and DeFelice, 2009). They finely serrated and include a white mark down the middle of the leaf (Bryson and DeFelice, 2009). Bryson and DeFelice (2009) aslo give that each inflorescence contains between 13-30 disk-shaped, reddish-purple florets. This perennial’s fibrous taproot is difficult to remove from the ground and is the reason why the plant gets the name “ironweed” (Bryson and DeFelice, 2009).

Portion of the Plant Used

The root is the main portion of the plant used, but many other parts including the stem and florets are used as well (Burgess, 2011).

Traditional Uses

In the past, the root of V. gigantea was used as a fever reducer, bitters for drinks, tonic for female usage during menstrual cycle and pregnancy, as well as a blood purifier (Crellin and Philpott, 1990). Today it is mainly used for its dyeing properties (Burgess, 2011).


Little if any research is being conducted on V. gigantea. A review of plants of the Vernonia genus with potential therapeutic uses revealed that V. amygdalina was used the most often and showed the greatest potential for treating malaria and diabetes, and V. cinerea for cancer and inflammation (Teryang and Verpoorte, 2013). The article also identifies Vernolide A as the most promising bioactive component for development of an anti-cancer agent. Farombi et al. (2011) review the chemopreventive and anti-oxidative properties of V. amygdalina. Ijeh and Ejike (2011) also review the medicinal potentials of V. amygdalina and conclude that future research must focus on identifying the active principles for the various reported effects and to determine if they act singly or in combination.

It has been shown by Koshimizu et al (1994) that the antiparasitic properties of related species V. amygdalina can help control parasite-related diseases by eating the pith of V. amygdalia. This could be due to the bitter constituents, of sesquiterpene lactones, such as vernodalin, which could control which one thinks is palatable (Koshimizu et al, 1994).

In Burnett et al. (1977) Eastern Cottontail rabbits seemed to prefer V. gigantea over V. flaccidifolia due to sesquiterpene lactone possession in V. gigantea. When V. flaccidifolia was coated with a thin layer of sesquiterpene lactones, it avoided the V. flaccidifolia (Burnett et al, 1977). V. flaccidifolia has also been shown to deter larvae away as well showing that these are coevolutionary results of the plant against the feeding species (Burnett et al, 1977).

Side Effects, Interactions, and Contraindications

Sesquiterpene lactones have been shown to irritate the skin (Bryson and DeFelice, 2009). Sesquiterpene lactones are a class of chemical compounds; they are sesquiterpenoids (built from three isoprene units) and contain a lactone ring, hence the name. They are found in many plants and can cause allergic reactions and toxicity if overdosed, particularly in grazing livestock.