Here is a longer shot of the same Vernonia plant. The tall grass to the right of the Vernonia is Indiangrass, Sorghastrum nutans. The other tall grass surrounding the Vernonia is big bluestem grass, Andropogon gerardii. Both are prairie grasses. The willows on the right of the scene are probably Salix interior.
This ironweed grows along the Monon Trail, just north of I-465, Hamilton County. All pictures taken August 14, 2010.