An herbaceous annual, the potato plant can grow to 20 to 40 inches (50 to 100 centimeters) high. The ends of its underground stems, or stolons, may enlarge greatly to form a few to more than 20 tubers of variable shape and size. The plant's compound leaves manufacture the starch that is stored in the potato's underground tubers. The plant bears white or purplish flowers. The skin of the potato tuber varies in color from brownish white to deep purple. Its flesh normally ranges in color from white to yellow, but it also may be purple. The tubers bear lateral buds (eyes) that grow into new plants when the conditions are right.