Uses : Edible, Forage, Xeriscaping, Polyculture. Native to : Central South America
I find that the sweet potato has a lot more to offer southerners than the white potato. White potatoes have been hybridized over centuries to be able to produce a great deal of starch in a short growing season. White potatoes grow very well in the North, but in the South, the sweet potato is king. Sweet potatoes require longer seasons but are able to thrive in the additional heat and humidity that white potatoes as we know them cannot. Known to be a super-food, it is an important source of Vitamin A (carotene) and other B vitamins.
Sweet potatoes are a staple of permaculture in the South, nothing screams ease of growth and abundance like the big orange spud. The potato itself is edible after cooking, and lower in carbohydrates but with plenty of vitamins and starches than white potatoes. The vines can be used as a fodder for livestock or cooked as a green for your table.
A study done in 2004 in Vietnam shows the crude protein content for sweet potato leaves to be between 25 - 30%, much higher than most other greens. It suggests that sweet potato leaves be included into the diets of animals as an important additional protein source.
Due to soil-borne plant diseases, it is recommended by IFAS not to plant sweet potatoes in the same place in consecutive years. Sweet potatoes are perennials if you neglect them, just be aware of the possibly of blights.
My vines tend to sprawl all over the ground rather than bother with climbing. Maybe they are just a lazy variety. For that reason they are a great ground cover, an erosion prevention tool rather than a plant to be used in a plant guild like the three sister's garden.