Monocots, or monocotyledonous plants, are distinguished by having leaves with parallel venation. In this arrangement, the veins run side-by-side along the length of the leaf blade, which is a key morphological feature used to differentiate them from dicots, which typically exhibit reticulate or net-like venation.

Dicotyledonous plants are characterized by reticulate venation, commonly referred to as a net-like pattern. In this arrangement, the veins branch repeatedly from the midrib to form a complex, interconnected network across the leaf blade. This structure provides structural support and efficient distribution of water and nutrients throughout the leaf, which is a key diagnostic feature distinguishing dicots from monocots, which typically exhibit parallel venation.

When the basal portions of leaves wrap around the stem or each other, they form a structure known as a sheath. This is a common morphological feature in many plant groups, including grasses and certain pteridophytes, providing protection to the developing stem tissues.

A typical leaf in dicotyledonous plants consists of three main parts: the leaf base, the petiole (the stalk that attaches the leaf to the stem), and the lamina or leaf blade (the expanded, photosynthetic portion). These structures work together to maximize light absorption and gas exchange for the plant.