Lewis and Clark State Park contains non-native grasslands, and native mixed grass prairie communities intermixed with wooded ravines and badland communities. The diversity of plant communities in the park provides for a variety of wildlife viewing and outdoor adventure opportunities.
Dominant plants of this mixed grass prairie include blue grama, little bluestem, needle-and-threat, prickly pear cactus, wild rose, buffaloberry and creeping juniper. Some wildflowers that can be observed include blazing star, white aster, torch flower, bluebell, purple coneflower and wild onion.
The green ash-elm wooded draw communities are extremely important to area birds and wildlife. The many chokecherry trees found here produce a summer fruit that attracts a variety of bird species such as catbirds, robins and towhees. The buffaloberry shrubs produce berries in the fall and are important both for migratory birds that build up fat reserves prior to migration and as a food source for non-migratory species that need to prepare for another North Dakota winter.