She likes to call the darker-fleshed varieties yams while reserving the term sweet potato for the lighter-colored ones.
I tell her that yams are a large, starchy African tuber and you can’t buy them at King Soopers, the Kroger affiliate where she shops. All of the root vegetables she sees at the grocery store, regardless of what the signs say, are just different varieties of sweet potatoes.
And of all people, my mom should be cognizant of differences in varieties, strains and species and try to get the nomenclature correct since she’s a scientist by training.
This is the same woman who consults textbooks to ensure the head lice and amoeba designs she’s knitting into sweaters are anatomically correct.
But this mislabeling got me wondering. How were the darker-fleshed sweet potatoes renamed yams?
Among the varieties erroneously called yams are beauregard, covington, garnet, diane and orleans — all dark-colored roots that also are also referred to as moist-fleshed because of their baking qualities.
The lighter varieties, including bonita and o’henry, are referred to as dry-fleshed varieties.
Scientifically, all sweet potatoes belong to the morning glory family. Sweet potatoes technically are enlarged storage roots, whereas yams are tubers that belong to an entirely different family.
The U.S. Department of Agriculture has acknowledged the differences and requires that any root sold in the U.S. that is labeled as “yam” be accompanied by “sweet potato.”
Part of the blame — or credit — for this confusion can go to Julian Miller and his colleagues at Louisiana State University.
When the state’s grower-packers began to market their sweet potatoes nationally in the 1930s, they chose to call the moist-flesh sweet potato coming out of Louisiana “yams” to distinguish them from other regions’ sweet potatoes.
Strangely, you don’t hear people ordering the latest fad, yam fries, in a restaurant. It’s sweet potato fries. At a friend’s house on Thanksgiving, someone had made a sweet potato pie, not a yam pie.
And it’s the U.S. Sweet Potato Council, not the Yam Council.
But old habits are hard to break. So I have a feeling that despite true botanical differences, retailers and marketers will continue to call the dark-colored root a yam.