Are Sweet Potatoes really Potatoes?

Although the English names 'potatoes' and 'sweet potatoes' suggest a close relationship between the two tuber / root vegetables, they are not even in the same botanic family: Potatoes (Solanum tuberosum) are of the nightshade family (solanaceae) while Sweet potatoes (Ipomoea batatas) are of the morning glory family (Convolvulaceae).