This 12.8-acre, high-quality prairie—located at 105th St. & Menard Ave.—is listed as an Illinois Nature Preserve. It is one of three gravel-based mesic prairies remaining in Illinois. The prairie boasts several species of endangered and unusual plants and insects. These include the state-endangered small white lady slipper (cypripedium candidum) and the geometric moth (Itameamboflava) for which the Chicago Ridge Prairie is the only documented location east of the Mississippi River! The prairie serves as a window to the past when Illinois was more than 90% prairie land. The Chicago Botanical Society, several university researchers, and local school groups are among those who regularly enjoy this remarkable ecosystem found in Oak Lawn.