Cassava is a tropical plant grown for its thick roots, which people eat, and for the flour and starch made from those roots. You may also hear manioc or yuca for the same plant. The root looks like a rough, barky stick; after it is peeled and cooked it is a main food in much of Africa, Latin America, and parts of Asia — cheap, filling, and able to grow in poor soil. The chewy pearls in bubble tea come from cassava. Though actually, you cannot treat it like a potato and always be safe: some kinds, called bitter cassava, hold a poison if you eat them raw or badly prepared. People who grow it know how to soak, grate, or cook it so it is safe. Sweet cassava is milder, but cooking is still the normal thing. It is not a sweet potato, and it is not taro.