Unearthing Sweet Potatoes at the UC Davis Library

Lithograph container label for Hillview California Red Yams,  A.T.Bettencourt of Turlock, CA
Courtesy of Special Collections, UC Davis Library. Lug Label Collection 1890-1940 , Coll no. D-211, 32:88

Lithograph container label for Hillview California Red Yams, A.T.Bettencourt of Turlock, CA Courtesy of Special Collections, UC Davis Library. Lug Label Collection 1890-1940 , Coll no. D-211, 32:88

I am on a mission to give sweet potatoes the recognition they deserve. This may seem like an odd quest, so let me explain. My sweet potato campaign began ten years ago, when I discovered my beloved candied yams, garnet yams and jewel yams are NOT yams. They are a softer and more sugary variety of sweet potatoes. I discovered this when I went to the market to get sweet potatoes for a sweet potato salad recipe. I could not find any sweet potatoes and the produce manager told me to just use the yams. Shocked, I said “Yams are not sweet potatoes,” and he replied “They are the same thing.”

My head filled with questions that needed answers:

  • “Are yams and sweet potatoes two different types of vegetables?”
  • “Are sweet potatoes and yams botanically related?”
  • “Why do we call sweet potatoes ‘yams’?”

At the time, I was working at the Library of Congress and so when I returned to work I went straight to my favorite food history reference books: The Cambridge World History of Food, The Oxford Companion to Food, and The Oxford Companion to American Food and Drink. And there, in the Oxford Companion to Food, was one simple sentence that changed everything, “In the USA the soft kind [sweet potato] is sometimes called ‘yam’; a misnomer, as the true YAM is a different plant (p.775).

Lithograph container label for Friedman and Broussard Louisiana Yam Sweet Potato, Lafayette, LA. Courtesy of Special Collections, UC Davis Library. Lug Label Collection 1890-1940 , Coll no. D-211, 34:135

Fueled by this discovery, I needed to learn more about the history of the delectable vegetable and to trace when all this yam/sweet potato confusion began. I immersed myself in old cookbooks, botanical illustrative works, horticultural handbooks, newspapers, food histories, manuscript collections, and anthropological studies. I contributed a page to the Library of Congress’ Everyday Mystery website, “What is the Difference between Sweet Potatoes and Yams?” and shared some of my findings in a blog post “A Sweet Potato History”.

My love and enthusiasm for the sweet potato was contagious. Through the years I assisted cookbook writers and food historians with their sweet potato research. Since my arrival at UC Davis, my sweet potato research has been put on hold until I received a call from NPR. They had tracked me down after reading my Library of Congress posts and wanted to interview me for a segment on sweet potatoes for Thanksgiving (The Myth of the American Yam). That interview inspired me to research the sweet potato in California history. What else can I unearth about the sweet potato from one of the best agricultural schools and collections in the world?

Planting Sweet Potatoes. From Merced County Where Location and Soil Make for Prosperity and Contentment (1915). Courtesy of Special Collections, UC Davis Library. California Collection (CAL 34:35)

I was surprised to discover in the UC Cooperative Extension’s Sweet Potato Tips, Jan. 2017  that California is the one of the largest producers of sweet potatoes, behind North Carolina and Mississippi. Prior to 2014, California was the second largest producer of sweet potatoes, but the state’s recent droughts have slowed production (you can find more information about the sweet potato in California from the UC Vegetable Research and Information Center’s sweet potato info page).

I decided to take a trip to the Library’s Special Collections to browse through its California Collection to learn more about sweet potato history in the Golden State. The California Collection is made up of late nineteenth and early twentieth century booklets and pamphlets that promoted California. Many of these booklets were available from the California Development Board and were freely distributed as a means to entice people to move to various counties in California. Also, these booklets tend to focus agricultural opportunities of a county. I focused my research on the Merced county booklets since this county is one of the largest producers of sweet potatoes in the state.

Lithograph container label for Little Miss Atwater Sweet Potatoes, Atwater, CA. Courtesy of Special Collections, UC Davis Library. Lug Label Collection 1890-1940 , Coll no. D-211, 38:81

The sweet potato information in these booklets was brief, but telling. According to Merced County Where Location and Soil Make for Prosperity and Contentment (1915), Merced had 2,800 acres dedicated to growing sweet potatoes in 1913, which yielded 21.5 million pounds. The “Merced Sweets” became a recognizable name in the marketplace and the town of Atwater was deemed the center of California’s sweet potato industry.

I then turned my attention to the  Lug Label Collection 1890-1940 (Coll. No. D-211) hoping to find sweet potato/ yam container labels. This collection currently boasts of seventeen sweet potatoes labels from Louisiana and California, with one label being from Texas.  There were only a few labels that featured yams (aka sweet potatoes)- Hillview Red Yams, CA (pictured), F&B Louisiana Yam Sweet Potatoes (pictured) and Sho-Am-Sweet Yams, CA (D-211;16:11). This collection continues to be added to and described – which may result in even more examples of vintage sweet potato/yam labels. For more information about the Lug Label Collection 1890-1940 please contact UCD Department of Special Collections.

Sweet Potato Storage. Livingston, CA, 12/26/40. Courtesy of Special Collections, UC Davis Library. Inventory of the Department of Biological and Agricultural Engineering Records, Coll no. AR-012, no. 5445

The last collection that I explored is the Inventory of the Department of Biological and Agricultural Engineering Records (Coll. No. AR-012) which contain subject files, correspondence, farm building plans, photographs, and other material related to the work of UC Davis’ agricultural engineering department.  I was especially interested in the images that were photographed by the department from circa 1915-1951. Included in this set of images are photographs and descriptions of sweet potato storage and buildings (pictured) from Merced county in the 1940s.

There is more sweet potato history to be unearthed at the UC Davis Library and I have just begun to uncover them.


List of Merced County books from the California Collection with sweet potato references:

Merced County Where Location and Soil Make for Prosperity and Contentment (1915). Shields Special Collections, Call no. CAL 34:35. Available online.

Merced County, California . Issued by the Crocker-Huffman Land and Water Company (1902). Shields Special Collections, Call no. CAL 34:33. Available online.

Merced County. California for Prosperity and Contentment (1918?). Shields Special Collections, Call no. CAL 34:35

Merced County, California: Attractions for the Homeseeker: Gateway to Yosemite . Issued by Merced Evening Sun, July 1913. Shields Special Collections, Call no. CAL 34:34. Available online.

The article was written by Jennifer “JJ” Harbster, a librarian at UC Davis.

Planting Sweet Potatoes. From Merced County where location and soil make for prosperity and contentment (1915). Courtesy of Special Collections, UC Davis Library. California Collection (CAL 34:35)