A herbaceous, perennial plant (family Solanaceae), up to about 60 cm tall, with foliage that dies back after flowering and the formation of small, green berries, and that forms starchy, edible tubers. The plant is native to South America, where it was domesticated, and it is now grown throughout the world as an important staple food, with about 5000 cultivated varieties. The foliage and green skin of tubers exposed to light are poisonous.