The most visible part of a tree are the leaves. These provide the surface area through which the plant traps solar energy and converts it to carbohydrates through photosynthesis. The main light absorbing substance of photosynthesis is the green pigment chlorophyll and so most leaves appear green.

Leaf Structure. Leaves have a large flat leaf BLADE or LAMINA the surface of which may be smooth or have hairs. The edge of the leaf is the MARGIN and may be entire, toothed or lobed. The leaf has veins which may be radial or branched. Some leaves have glands, often at the base of the leaf where the leaf is joined to the stem by the PETIOLE or leaf stalk.