venation

(veination) The pattern formed by the veins of a leaf, as viewed from above or below. The many different types of venation (see illustration) are useful diagnostically, especially in identifying fragmentary material. As a very general rule, the leaves of monocotyledons tend to have many parallel veins of more or less equal width while those of dicotyledons may be divided into one or a few primary veins, with secondary and tertiary veins branching off giving a net-veined or reticulate pattern.