Sweet potatoes are not potatoes, and those other long orange root vegetables are not yams. The confusion between these vegetables have been around for what seems forever.
Let’s try to clear up a few things.
Yams and Sweet Potatoes?
Yams, are part of the dioscorea genus of plants. Sweet potatoes are grown as the roots of ipomoea batatas plant, which you may also know as morning glories.
- Yams contain just over 10% of the sugar a sweet potato has
- Yams have nearly double the potassium as sweet potatoes
- Yams have much less vitamin A and beta-carotene than sweet potatoes
- Yams are usually dark yellow to light pink, sweet potatoes come in a variety of colours from yellow to red to purple
In cooking, they are not substitutes for each other. A sweet potato and a yam are two different plants, with two different flavours and nutritional content. What you may be calling a “yam” may actually be a sweet potato, so always make sure to double-check.
Sweet Potato versus Potatoes
Sweet potatoes, despite having potato in their name, are only very distantly related to “normal” potatoes. Most potatoes belong to the same family of plant that contain nightshade, which explains why the leaves of the potato plant can be poisonous. Some sweet potatoes’ flowers are called morning glories, and people may even grow them for decoration.
The two, sweet potatoes and potatoes, do have vastly different flavours and nutritional content. Again, sweet potatoes are very high in sugar, while potatoes have more protein.
Needless to say, they cannot be used as substitutes for each other. But, many techniques you use to cook a potato can be applied to a sweet potato (cooking, frying, baking, mashing etc.).
Vox produced this video to explain the difference between sweet potatoes and yams, as well as explore the reasons for the confusion.