How a sweet potato became a yam, but not really

Published 9:17 am Friday, November 29, 2019

I’m not sure how that 28 ounce can of sweet potatoes got up in my kitchen cabinet with the other canned goods. 

I came across it Thanksgiving Eve looking for the can of condensed milk I remembered buying a few years back. 

Surely I wouldn’t have planned at some point to make a pie with canned sweet potatoes, already cut up and in a light syrup. And to make things less authentic, big letters on the can read “SWEET POTATOES/YAMS.” 

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A yam pie? Is there such a thing?

Some years ago I drove passed the Louisiana Sweet Potato Research Station on my way to and from work each day. 

I got to know about sweet potato research, farming, grading and marketing fairly well. 

Then I moved to work here and found out about sweet potato production at and around Vardaman. 

About half the sweet potatoes produced in the U.S. are grown in North Carolina, with Mississippi and Louisiana typically jockeying for second-tier ranking in production. 

It is purchasing, recipes and consumption that usually brings on the questions regarding the differences, if any, between sweet potatoes and yams. 

To be sure, they are two different plants and not even closely related. Sweet potatoes are tubers, outgrowths from stems for food storage. They are members of the large Ipomoea plant genus, making them closely related to morning glories. 

Yams are in the Dioscorea genus. Allegedly true yams have a texture and flavor more similar to edible yucca rather than sweet potato. I say allegedly because most of us have probably never tasted a yam.  Nor do we see yams displayed as supermarket produce. 

Yams tend to be popular menu items in the Caribbean countries as well as areas of West Africa. In fact, the term “yam” is an English aberration of an African language name for the plant.

The story of how sweet potatoes became to sometimes be called yams, which they are not, is akin to the old explanation “follow the money.” It was all in the marketing. 

Sweet potatoes have been grown and consumed in this country for over 200 years. For most of that time, the sweet potatoes here had a dullish white or brownish flesh, not totally unlike real potatoes, which they also are not.  Eventually, researchers developed varieties with near-orange flesh and even sweeter taste. 

Some marketers began using the term “yam” to differentiate the new, colorful and sweeter varieties from the older ones. 

During the 1930’s, the Louisiana Department of Agriculture came up with “Louisiana Yams” as a promo for sweet potatoes produced there.   

Make no mistake about it, that Thanksgiving sweet potato pie or casserole, whether freshly made or store-bought, was made with sweet potatoes, not yams. 

I couldn’t bring myself to open the can of “SWEET POTATOES/YAMS,” ever how I came to own it. So I peeled, sliced, boiled and mashed the real things and I slowly began to recall why and how the can got here. 


Terry Rector writes for the Warren County Soil and Water Conservation District.