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. Potatoes have become a staple food in many parts of the world and an integral part of much of the world's food supply. Potatoes are the world's fourth-largest food crop, following maize (corn), wheat, and rice. Tubers produce Glycoalkaloid in small amounts. If green sections (sprouts and skins) of the plant are exposed to light the tuber can produce a high enough concentration of glycoalkaloids to affect human health.