Understanding Pinnate-Veined Leaves: Structure and Function

Pinnate-veined refers to a type of leaf venation in which the veins branch off from a single point, called the base of the petiole, and then divide into smaller veins that radiate outward from the center of the leaf. This type of venation is characteristic of many species of flowering plants, including those in the families Asteraceae, Fabaceae, and Rubiaceae.

In pinnate-veined leaves, the main vein (or midrib) runs down the center of the leaf, and is flanked by smaller veins that branch off from it. These smaller veins are called secondary veins, and they may further divide into tertiary veins, which are even smaller. The arrangement of these veins gives the leaf a feathery or pinnate appearance, hence the name.

Pinnate-veined leaves are often found in plants that are adapted to dry environments, as the branching veins help to reduce water loss by allowing the plant to distribute water more efficiently throughout its leaves. This type of venation is also common in plants that have large, flat leaves, such as those in the genus Acalypha.