Prairies are made up of mostly grasses, sedges (grasslike plants), and other flowering plants called forbs (e.g. coneflowers, milkweed). Some prairies also have a few trees. Wisconsin's prairies fall into three basic types. Combinations exist where two different types meet.
Wet Prairie: Lots of water, deep clay silt loam or peat soil, poor drainage. Marsh milkweed and prairie cordgrass are two species of plants common to the wet prairie.
Mesic Prairie: Some water, medium-deep silt or sandy loam soil, good drainage. These areas are dominated by tall grasses: big bluestem and Indian grass. Here you will also find rosinweed and yellow coneflower. By late summer, flowers of the mesic prairie may reach 4 to 6 feet high.
Dry Prairie: Little water, dry shallow soil over sand or limestone. Dry prairies on steep slopes are also called "goat prairies." Little bluestem, sideoats grama, and purple coneflowers can be found here.
Many prairie plants are adapted for a dry, windy, hot climate. Leaves of prairie plants tend to be long and narrow to prevent overheating. Some plants have divided leaves or broad leaves held stiffly upright, to expose less surface to the sun. Fleshy, hairy leaves and sticky sap help hold in moisture. Plants also have buds at or below the soil surface and a lot of root mass below ground--an adaptation to the natural fires that occurred in the grassland ecosystems. Prairies need fire. Without it, invading trees and shrubs gradually turn grasslands into woodlands.
In places where grasslands neared the forest edge, oak trees spread out across the prairie. Settlers called these parklike grasslands "oak openings." Today, they are known as oak savannas. A prairie oak's shade creates a microclimate underneath its boughs, allowing prairie plant species with broader leaves to thrive in the cooler, more even temperatures and moister soils.
Prairie soil is rich soil. It is this richness that attracted European farmers and altered the prairie landscape. Today, only scattered remnants of tallgrass prairie and oak savanna remain in Wisconsin. They are places well worth visiting. Check out some of the many other plants and animals that live in the prairie.
--Information compiled from A Pocket Prairie Guide, Wisconsin Department of Natural Resources, Plant Species Composition of Wisconsin Prairies, Wisconsin Department of Natural Resources, and Prairie Restoration for Wisconsin Schools, University of Wisconsin-Madison Arboretum.