There are over five thousand varieties of potato, over a thousand species of sweet potato, and many kinds of French fries, but no evidence for the existence of the Society for the Prevention of Unwholesome Diet (S.P.U.D.), even though the spud is related to the deadly nightshade. We eat the tuber of the potato; the roots, the leaves, and the fruit contain the toxic alkaloid solanine, which can give you nausea, diarrhea, vomiting, cramps, headaches, dizziness, dysrhythmia, joint pain, and nightmares. The Russians make vodka using potatoes, and vodka can produce similar symptoms. Nevertheless, potatoes, though never eaten raw, are dried, fried, roasted, baked, boiled, and steamed, powdered, mashed, cubed, made into pancakes and served both hot and cold.