If there are two leaves at each node, they are arranged oppositely on the stem. And if there are more than three leaves to a node, they are arranged in whorls. The angle formed by the stem and leaf stalk is called the axil, and buds formed in the axils are called axillary buds. A leaf can be an important aid in identifying a flower. In some instances, the petiole is absent and the leaf then is sessile on the stem.
Leaves can be either simple or compound.
For a simple leaf, the blade consists of a single piece. Leaflets never have axillary buds, but compound leaves always have one at the base. Leaves and leaflets come in a vartety of shapes and forms. In addition, leaf margins or edges can be smooth, or entire, scalloped, serrate, deeply lobed, toothed, or even double toothed. Another distinguishing feature for leaves is the type of venation.