According to Northwest Missouri State University, a leaf can be simple or compound. This is determined by the leaf’s blade and petiole attachment. Simple leaves have buds that are located where the petiole meets the stem of a single leaf. Compound leaves have the same petiole attachment, but are divided into multiple sections and can be palmate, pinnate or bipinnate. Leaves are also categorized by edge and blade shape.
Palmate leaves are composed of small leaflets that connect at a shared point and spread out like the fingers on a hand. Pinnate leaves have a center nerve, the midrib, with attached nerves that fan out like a plume. Bipinnate leaves are pinnate leaves that are divided into two halves.
Leaves with wavy edges are called sinuate leaves, while the edges of entire leaves are smooth. The edges of dentate leaves look like teeth, and serrate leaves are saw-like. Lobed leaves have rounded divisions that do not reach the center. Blades that are shaped like spears are called lanceolate, and blades shaped like needles are called acicular. Egg-shaped leaves, also referred to as ovate, have wide bases. Linear leaves have blades with a length that is much longer than their width. Elliptical leaves have a width that is two to three times shorter than their length.