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Summer 2011

Urban Jungle

The changing natural world at our doorsteps | Illustration and text by Patterson Clark      

August 23, 2011

Ironweed: A flinty flower


It's tall and it's tough, and it's probably more welcome in the city than in the country.

Ironweed was named for its rugged stalks, which stubbornly persist throughout the winter. Its underground stems are equally tenacious, sending up sprouts even when repeatedly mowed.

The plant's vivid purple flowers may look lovely in a cityscape, but they are a bane in the pasture. Cattle and horses won't eat the bad-tasting leaves, which allows the plant to spread and crowd out vegetation more suitable for grazing. (Deer avoid ironweed, too — another good reason to include the native plant in a flower bed.)

But goats will munch away on ironweed, prefering it to grass, so some ranchers include goats with their cattle herds to keep the weed under control.

The tough digestive system of goats can tolerate the bitter compounds in ironweed leaves, which repel most insect and mammal herbivores.

Some ironweed compounds were used in the past to prevent atherosclerosis and alleviate the pain of childbirth. Extracts from ironweed also have shown promise in treating malaria and reducing the desire to smoke tobacco.

SOURCES: Ohio State University, Journal of the Arnold Arboretum, Western Kentucky University

Ironweed, Vernonia