The understory is the rainforest layer between the forest floor and the canopy. It receives far less sunlight than the canopy above, so it is dominated by shade-tolerant shrubs, herbs, young trees, and woody vines rather than the tallest mature trees.
In many tropical rainforests, only about 5% of sunlight that reaches the canopy penetrates into the understory. Plants growing there often have large leaves that capture scarce light efficiently. Many seedlings that may eventually become canopy trees begin life in this dim, humid zone.
The understory is also an important animal habitat. Birds, reptiles, amphibians, insects, and small mammals move through its dense vegetation, while predators use the cover for hunting. It is easy to confuse the understory with the forest floor, but the floor is the lowest layer, covered by leaf litter and decaying organic matter. The canopy forms the forest’s leafy roof, while the emergent layer consists of occasional trees rising above it.