Pachyrrhizus erosus or P. tuberosus — a tropical legume commonly called jicama. The young pods serve as a vegetable, but mature seeds are poisonous; the large turnip-like tubers are thinly sliced for raw eating — crisp, juicy, and mildly sweet. Only the tuber should ever be eaten — a critical safety distinction, since the seeds contain the insecticidal compound rotenone. Its high water content makes it refreshing in salads and salsas. It stays crisp after cutting, unlike apples that brown quickly.