Yam

The yam is a large, starchy underground tuber of climbing vines in the genus Dioscorea, a staple food across West Africa, the Caribbean and tropical Asia. A true yam is a heavy, cylindrical tuber sheathed in rough, bark-like brown skin and packed with dense white or pale-yellow starchy flesh — bland and faintly sweet, eaten boiled, roasted, fried or, most famously, boiled and pounded into the smooth, stretchy dough called fufu. It should not be confused with the sweet potato, an unrelated root frequently mislabelled yam in the United States.