In a forest, the layer of shrubs and young trees beneath the canopy is called the understory. It receives less light than the upper tree layer but often supports substantial plant and animal diversity.
The understory may contain saplings, shade-tolerant trees, shrubs, herbs, ferns and climbing plants. Its exact height and density vary between forest types, from open woodland to dense tropical rainforest.
The canopy forms the relatively continuous roof created by mature tree crowns. Above it, some tropical forests also have an emergent layer made up of trees that rise above the main canopy.
The understory is not the same as the forest floor. The forest floor is the ground-level layer of leaf litter, fallen wood, soil organisms and decomposing material, while the understory occupies the vegetation space above it.