The potato is a starchy, tuberous crop from the perennial nightshade Solanum tuberosum. Potato may be applied to both the plant and the edible tuber. Potato has become a staple food in many parts of the world and an integral part of much of the world's food supply. It is the world's fourth-largest food crop, following maize, wheat, and rice. The green leaves and green skins of tubers exposed to the light are toxic.