Term:

Adaxial
Definition:

The upper part of a structure such as a leaf, i.e., that part of the structure that faces toward the main axis to which it is attached. For example, if a leaf is pushed upward and against a stem the surface facing toward the stem is the abaxial surface.
Notes:

In neotropical Lecythidaceae, this term is commonly used to describe the differs in color between the upper (adaxial) and lower (abaxial) surfaces of leaves. In nearly all species the abaxial surface of a leaf of Lecythidaceae is lighter in color than the adaxial surface.