The topic of sweet potato diversity is pretty obscure. If they think about it at all, most folk believe that the extent of it is that there are some red colored sweet potatoes beside the regular orange ones, found in the supermarket. Don’t let the supermarket fool you. Sweet potatoes are far more diverse than that!
Sweet potatoes differ greatly in eating qualities.
There are varieties of sweet potato with flesh colors of yellow, orange, purple, white and just about every shade between. One of our kids once studied in Ecuador for a semester and purchased sweet potatoes in the market for an expat Thanksgiving celebration. They were sweet potatoes, alright, but their flesh was mottled orange and purple. Flesh color is an obvious difference between many varieties.
Sweet potatoes can have skin color in almost any shade found in their flesh color, but skin color and flesh color are not tightly tied together in sweet potatoes. There are varieties with dark purple skin and white, yellow, or orange flesh. The typical copper colored skin can cover yellow or orange flesh. I can’t think of a copper skinned variety with purple or white flesh, but there might be one. Skin color has no effect on flavor. The only use I have for it is in helping to distinguish varieties
There is a huge range of difference in moisture content of sweet potatoes. In the United States there is a commercially contrived distinction between moist and dry sweet potatoes. They call the moist ones yams, when in fact they aren’t really. They’re just moist fleshed sweet potatoes. See North Carolina Sweet Potato’s article on the difference between yams and sweet potatoes.
There are really moist fleshed sweet potato varieties and there are drier fleshed varieties. Don’t assume that moister is always better. That depends on personal taste, and perhaps, on how one wants to use the sweet potato. Molokai is the driest fleshed variety I have experienced, yet year after year it is one of the most popular varieties I sell as slips. Grand Asia, is a red/purple skinned, white fleshed variety that is fairly dry, yet it is one of my personal favorites on account of its delicate sweet flavor.
Not only are there sweet potato varieties which are sweeter than others, there are varieties with subtly different kinds of sweetness. There are those with more of a caramel like sweetness and there are others which are sweet and mealy. White Eclipse is dry, yet surprisingly sweet when properly cured. It’s important to note that “flavor” consists of more than just “sweetness.” So, how does one know what variety will be their favorite? The only way to know is to try a number of varieties and evaluate them for oneself.
There’s a range in flesh firmness. It’s between “mushy” and “kinda hard.” Pardon my scientific terminology. Just like other characteristics which affect palatability, this is a matter of personal preference. For that reason there are varieties with differing degrees of firmness when cooked. White Eclipse is the firmest fleshed variety I’ve tried, yet it is really sweet and delicious. For someone only accustomed to supermarket sweet potatoes, White Eclipse might blow their minds. It’s so different both in regard to color and firmness! Yet it is super prolific and quite tasty. I suspect it would be a superstar for sweet potato fries.
There are other taste factors than what have already been mentioned. Some are almost like candy. Sweet potatoes can have a lighter, sweeter flavor, a mealier more “substantial” consistency or even the distinctive taste of anthocyanins, the antioxidant substance so highly valued in purple sweet potatoes. (I hope I’m not the only person who can taste them!)
Sweet potatoes have a wide range in growth habit.
There’s variation in vine size and length. Some are short and bushy in form. Others have very long vines. There are differences in leaf style. Not only are there the regular heart shaped leaves, but some have split leaves. Within these differences there are distinct nuances which only the grower is likely to notice.
There are even differences in shape of the roots and how they are placed under the plant, which is a great reason to grow the same variety for more than a year. It helps to get to know one another!
The sweet potato could actually help re-write ancient history.
Sweet potato diversity is both wonderful and important.
There are even more differences to be noted than what I’ve mentioned. Some varieties do better under special conditions. Oklahoma Red, for instance, thrives better than many others in heavy clay soil.
We face a problem in regard to sweet potato diversity.
This diversity must be maintained. Though there may be a way to preserve seed stock which I don’t know about, the main method of preservation is to grow each variety every year, saving roots for making more slips. This is not difficult but it involves time, work and garden space. There is a shortage of preservationists working with sweet potatoes. I’ve always promoted both Sandhill Preservation Center and Duck Creek Farms. These two vendors have grown and maintained more varieties than anyone I know. Yet Duck Creek Farms is getting out of the sweet potato slip business. I maintain and sell about a dozen varieties, which is my limit.
A dozen varieties is about all I can maintain.
I guestimate that it would take about at least 50 of me to make up for one of these suppliers, probably more. I intend to write a lesson, about how to produce and sell slips (cuttings) for Homesteading Edu’s course on “Growing Sweet Potatoes.” This is an activity which I LOVE. Perhaps you might enjoy it too. We need lots of gardeners to adopt these varieties and to make them available to others. Would you consider this?
Sweet potatoes are diverse, and the best way to keep them that way is to grow and use them.
The best “seed repository” is a group of people growing, using and sharing a variety. This is especially true for root crops like potatoes (Irish) and sweet potatoes. Almost nothing would go farther in sweet potato preservation than to help lots of people experience sweet potato diversity for themselves!
Do you know anyone who is maintaining an heirloom sweet potato? We would LOVE to hear about it in our comment area!