A leaflet (occasionally called foliole) in botany is a leaf-like part of a compound leaf.[1] Though it resembles an entire leaf, a leaflet is not borne on a main plant stem or branch, as a leaf is, but rather on a petiole or a branch of the leaf.[2] Compound leaves are common in many plant families and they differ widely in morphology.[3] The two main classes of compound leaf morphology are palmate and pinnate.For example, a hemp plant has palmate compound leaves, whereas some species of Acacia have pinnate leaves.
The ultimate free division (or leaflet) of a compound leaf, or a pinnate subdivision of a multipinnate leaf is called a pinnule or pinnula.