The Mayo Clinic classifies beans as a fruit. According to botanists, a fruit is the part of the plant that develops from a flower or the section of the plant that contains the seeds. The other parts of plants are considered vegetables.
A common misconception is that beans are legumes and that legumes are neither fruits nor vegetables. Beans are indeed legumes, but legumes are simple, dry fruits contained within a shell or a pod. The most well-known legumes are peas, beans, peanuts and alfalfa. Legumes are a good source of protein, especially for those who abstain from eating meat.