Vernonia Gigantea OR''

Vernonia Gigantea OR''

Vernonia Gigantea

Vernonia gigantea (Giant Ironweed) is a tall, clump-forming perennial boasting dense, broad, flattened clusters of tiny, fluffy, intense purple, finely petaled flowers in late summer and early fall. Each glorious flower head may consist of up to 30-50 flowers. Attractive to birds and butterflies, the blossoms are borne atop stiff, upright stems clothed in lance-shaped, deep green leaves. They give way to fluffy, rusty seed clusters. As a tall, narrow plant, Giant Ironweed is suited for the back of the border or tight spaces and grows well in the native meadow garden and along ponds and streams.


This species is found most often on the eastern side of the Mississippi River valley. Tall Ironweed prefers wet soil conditions and full sun exposure. This plant spreads by rhizomes to form clumps. Because it can spread aggressively, Tall Ironweed is often categorized as a common pasture weed, but is endangered in New York. It will readily self-hybridize with other Vernonia spp. like Vernonia fasciculata (Common Ironweed) , Vernonia missurica (Missouri Ironweed), Vernonia baldwinii (Western Ironweed), and Vernonia noveboracensis (New York Ironweed) which can make plant ID difficult in the field.The nectar of the flowers attracts bee flies, butterflies, skippers, and various bees (primarily long-tongued bees). Some bees also collect pollen for their larvae. The caterpillars of various moths feed on Vernonia spp. (Ironweed species), particularly the pith of their stems and their roots. These species include Carmenta bassiformis (Eupatorium Borer Moth), Papaipema cerussata (Ironweed Borer Moth), Papaipema limpida (another Ironweed Borer Moth), Perigea xanthioides (Red Groundling), Polygrammodes flavidalis (Pyralid Moth sp.), and Polygrammodes langdonalis (Pyralid Moth sp.).

Another insect, Aphis vernoniae (Ironweed Aphid), sucks juices from the upper stems and leaf undersides. Other insects feeders include the larvae of Asphondylia vernoniae (Ironweed Bud Midge) and Youngomyia podophyllae (Ironweed Blossum Midge), which form galls on the buds and flowerheads respectively. Both Oecanthus quadripunctatus (Four-Spotted Tree Cricket) and Conocephalus brevipennis (Short-winged Meadow Katydid) have been observed feeding on the flowerheads of Tall Ironweed (Gangwere, 1961). Because of the bitter foliage, mammalian herbivores shun Ironweed species as a food source. As a result, these plants can become more abundant in pastures over time.The native Tall Ironweed is common in southern Illinois, while in the rest of the state it is occasional to absent (see Distribution Map). Habitats include open woodlands, woodland borders, thickets, areas along woodland paths, swamps, riverbottom prairies, seeps and springs, pastures, and abandoned fields. In woodlands, this plant requires occasional disturbance to prevent excessive shade from neighboring trees. Tall Ironweed is found in wooded areas to a greater extent than other Vernonia spp. (Ironweed species) in Illinois, but it also occurs in moist open areas. (Source:www.illinoiswildflowers.info)



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