Big bluestem prairie grass (Adropogon gerardii); photo by Dendroica cerulea on Flickr (use permitted with attribution).
Official State Prairie Grass of Illinois
Illinois designated big bluestem grass (Adropogon gerardii) as the official state prairie grass in 1989 following a poll of students conducted by the Illinois Department of Conservation. All State Grasses & Plants
Big bluestem was the most abundant grass on the prairies that once covered most of Illinois (the state nickname of Illinois is "The Prairie State"). The North American prairie is one of the most endangered ecosystems on earth. The grasslands of North America began to form about 20 million years ago, but in some areas up to 99 percent of the prairie has been destroyed (in just the last 125-150 years).
Wildflowers are the jewels of public lands; tread lightly, take only photos and memories - do not pick flowers or dig up native plants and grasses.