The groundcover or herbaceous layer consists of grasses and forbs and ferns - non-woody plants without a perennial stem. These herbs include spring ephemerals such as, spring beauty (Clatonia virginica), Jacob's ladder (Polemonium reptans), bloodroot (Sanguinaria canadensis) and purple trillium (Trillium recurvatum), all of which appear for a short time in Illinois forests in early spring.
The light intensity reaching the herbaceous layer is very low unless the canopy is fairly open, as in the case of savanna and barrens. Many of the plants in this layer are adapted to low light levels and flower early in the spring before the trees leaf out. They fade from the scene as summer arrives and broad leaves appear on the trees. In savannas and barrens, the canopy is open enough to permit the growth of prairie grasses and other herbaceous plants that require high light levels.