What’s in Bloom | Ironweed
August 19, 2020
Ironweed (Vernonia noveboracensis, V. gigantia, V. glauca) is a tall perennial forb in the Sunflower family (Asteraceae). There are many different species of ironweed across the United States, but the most common in Northern Virginia are New York Ironweed (Vernonia noveboracensis), Giant Ironweed (V. gigantea) and Broadleaf Ironweed (V. glauca). Ironweed grows tallest in moist conditions, but established plants are also tolerant of drought. It can be found in pastures, grasslands, roadsides, and forests.
Ironweed leaves are dark green and typically lance shaped but can also appear more feathery. The leaves are 4-12” long and about 1” wide. The plant can grow from 3-9’ tall depending on the species and growing conditions. The name is thought to come from the rigidness of the stems that can persist through winter or the rusty color of the seed heads that appear in the fall.
Ironweed exhibits beautiful purple flowers in summer through early fall. The flower heads are made up of many compact tubular flowers and there are typically 10-20 blooms atop a branch. Overlapping flower heads creates the appearance of large flower masses.
Benefits to Biodiversity | Ironweed is an excellent source of nectar and is often visited by native bees and other pollinators. It is a host plant for the American Lady butterfly (Vanessa virginiensis). Adding a native ironweed to a pollinator garden will allow you to enjoy the stunning purple flowers and constant pollinator activity all summer long!
Eastern tiger swallowtail visiting a patch of ironweed 
V. glauca with creamy-white to tan pappi 
Spicebush swallowtail on New York Ironweed 
Snowberry clearwing moth on New York ironweed
Sources: USDA, MGNV, Chicago Botanic Garden