Why are pea and bean pods classified as legumes?

Pea and bean pods are classified as legumes because they are the characteristic fruit type produced by plants in the Fabaceae family.12

Botanically, a legume is defined by specific structural features:
* Single Carpel: The fruit develops from a single pistil (or carpel), which is a simple, hollow structure.13
* Dehiscence: In their typical form, these fruits are dry and dehiscent, meaning they split open along both the dorsal and ventral sutures (edges) at maturity to release their [seeds].123
* Seed Arrangement: They bear a single row of ovules along the upper suture of the pod.13

While some members of the family have evolved variations—such as fruits that do not split open or those that break into segments—the pea and bean pod represents the basic, idealized model of this fruit type.1