The plant is 3–5 feet (0.91–1.52 m) high and 3–4 feet (0.91–1.22 m) wide, and in some cases the plant can exceed up to 6 feet (1.8 m). The leaves of the plant are dark green in color and alternate.
The flowers bloom from July to August, and are magenta colored with reddish-brown bracts. Each flower is from 4-7 inches long and 1/2 inches across, with 30-60 disk florets. They have central stout stem that is covered with white hairs. The flowers grow close to each other and have rayless heads. Their stems are hairy and reddish-brown in color.
The plant is pollinated by various bees such as bumblebees, epeoline cuckoo, halictid bees, and miner bees. butterflies and skippers are also a frequent visitors. Some of the caterpillars feed on the plant. The most common guests are Grammia parthenice (Parthenice tiger moth), Perigea xanthioides (red groundling), and Papaipema cerussata (ironweed borer moth). Herbivorous mammals avoid the plant due to their bitter taste.
- "Vernonia missurica". Natural Resources Conservation Service PLANTS Database. USDA. Retrieved 29 July 2015.
- "Vernonia missurica". Missouri Botanical Garden. Retrieved 8 September 2012.
- "Great Ironweed". Retrieved 8 September 2012.
- "Ironweed (Vernonia missurica)". Michigan.gov. Retrieved 8 September 2012.
- "Missouri Ironweed". Illinois Wild Flowers.info. Retrieved 8 September 2012.