Arrangement of veins and veinlets in the lamina is known as Venation. It is of two types:
Reticulate venation - veins forming a network. Example: dicots
Parallel venation - veins arranged in parallel rows. Example: monocots
Reticulate and parallel venation may be unicostate with one mid rib, giving out secondary veins like in feather, hence pinnate or, multicostate having many strong veins spreading out from a common point like fingers from palm, hence palmate.