Geissler Savanna is one of the rarest and most imperiled natural communities in Illinois, the tallgrass savanna. The Illinois Natural Areas Inventory originally identified only 11.2 acres of high quality, dry-mesic and mesic savanna in the entire state. Geissler Savanna is the second largest intact savanna of this type in Illinois.
Lying within the picturesque rolling hills of west-central Illinois, the widely scattered groves and oaks and native shrubs of Geissler Savanna compliment an understory of prairie wildflowers and grasses.
Nearly 100 native species including Indian grass, big blue stem, white wild indigo, purple milkweed, spiked lobelia, tall green milkweed and pale purple coneflower inhabit these unique hills.
State and Federally threatened and endangered plants include: Mead's milkweed, eastern prairie white fringed orchid and Virginia bunchflower.
Geissler Savanna was acquired by Save the Prairie Society from Byron and Carol Geissler and later transferred to the Illinois Department of Natural Resources for protection in perpetuity.