The main ingredient in tapioca pudding is a tropical tuber that provides more of the world’s carbohydrates than any crop beside rice or wheat. After rice and wheat, the most important human carbohydrate source is not what you might guess. It’s not the starchy potato, or any of the major sweetener-producing crops such as sugar cane, sugar beet or corn) It’s a tropical tuber known by the names cassava, manioc and yuca (in Spanish), and it’s the main ingredient in tapioca pudding. Although little known in North America, cassava was a staple food for the pre-Columbian cultures of tropical America and remains an important food in that region of the world today. It has also acquired a central place in African cooking, and is a major calorie source for that continent. That’s because cassava is both versatile and highly nutritious. It is a good source of fiber, calcium and phosphorus, among other essential nutrients. In addition to being cooked and eaten like a potato, cassava can also be ground into a flour. The starch of the cassava is not called “cassava starch” (as you might expect based on “corn starch” or “potato starch”) but tapioca, and is most famously used in puddings and in the “boba” balls of certain Asian teas.