Understanding the Yam #

Before getting into cultivation and history, it helps to pin down the central fact of the whole book: a true yam is not a sweet potato. In North American grocery-store language the terms often blur together, but botanically they do not.

What is a True Yam? #

True yams belong to the genus Dioscorea in the family Dioscoreaceae. They are monocots, meaning they begin life with a single seed leaf. Unlike many tuber crops, they grow on climbing or trailing vines and can produce very large starchy tubers.

The Yam vs. Sweet Potato #

Here are the quickest ways to separate them:

• Botanical family: yams are Dioscoreaceae; sweet potatoes (Ipomoea batatas) are Convolvulaceae, the morning-glory family.
• Physical traits: true yams usually have rough, bark-like skin and drier, starchier flesh.
• Origin: true yams are associated primarily with Africa and Asia, while sweet potatoes arose in the Americas.

Keep that distinction clear, and the rest of the book becomes much easier to follow.