The N Carolina Sweet Potato Institute: Sweet potatoes, or Ipomoea batata, are native to South America and were in Polynesia (~1000AD). Some historians think early South American voyagers actually introduced the tuber to the South Pacific .Native Americans were growing sweet potatoes when Columbus came in 1492. By the 16th century, sweet potatoes were being cultivated in the southern US states, where they became a staple in the traditional cuisine. A true yam is from the Dioscorea family of perennial herbaceous vines. It is thought it was imported to America from the Caribbean.
Storage: Do not store any spuds in the fridge. Store all potatoes in a cool, dry, well ventilated place like a basement or root cellar away from heat sources. If done properly spuds can be stored for weeks, but check once a week and rotate to see if there are any soft spots.
Beauregard Sweet Potato:
These were developed in 1987 and are now the most common “sweet potatoes” used in Thanksgiving Dinner. Sweet nutty flavor with a lovely orange flesh that has a great smooth texture. I use for squash-type dishes and stuffed.
Hawaiian Purple Yams:
On Okinawa, Japan these potatoes were one of the few types of vegetables able to survive typhoons and tropical storms. Eventually, Polynesians brought the purple sweet potato to the rich, volcanic soils of Hawaii, where it continues to flourish today. They tend to be a bit more dense and dry, so they do take a bit longer to bake. (1)
Japanese “Mountain Yam”
I have to admit right up front I have never eaten these. I am relying on a website to inform you of this food as I have seen it in the Market.
This is the tuberous root of a climbing vine. Grating the mountain yam immediately transforms it from a fairly common-looking root vegetable into a pile of sloppy white goo. Mildly sweet (like jicama) it is pan-fried until the surface is browned and crisp and the interior is soft and tender. (2)
Japanese Yams:
Often listed as a Japanese Yam, but it is not a true yam. The skin on the outside is purple-red while the inside is completely white. Great for mashing, with an almost chestnut flavor.
It is roughly oblong in shape with a thin, rusted red colored skin, and a densely textured cream colored flesh. The flesh is dry, starchy and subtly sweet. The skin retains the bitter flavor of the root so definitely peel prior to eating.
Japanese Sweet Potato, or Satsumaimo:
This is a very sweet sweet potato, in the oven the sugars carmalize and turn a darker shade of brown as it cooks.
Red Garnet Sweet Potato:
Savory flavor (not sweet) with orange flesh, but a looser and watery texture. Almost like a squash. Sometimes called red sweet potato, both skin and flesh has a darker color. These are a favorite for baking, like for a sweet potato pie.
Okinawan Purple Sweet Potato:
An Americas plant, brought to Japan between 1492 and 1605. It is purple inside and out and the color intensifies when cooked. These have an unique flavor and are drier their orange/red cousins. (3)