Good Oak News

Monday, December 15, 2014

yams vs sweet potatoes: a local interest story

So, the annual 'yams vs sweet potatoes' issue came up at dinner last night. Turns out there's a local angle to this story!

Sweet potatoes are in the morning glory family (Convolvulaceae). In fact, they are are in the same genus (Ipomoea) as these showy ornamental vines. Wild local members of this family include the native hedge bindweed and troublesome, introduced field bindweed. What we at Thanksgiving and Christmas are, in-fact sweet potatoes, even though some people call them yams. I think I got that habit from my grandpa who was an old farm boy.

Hedge bindweed is actually pretty closely related to sweet potato. Who knew?

True yams, are in-fact monocots, making them more closely related to grasses, orchids and lilies than they are to any kind of potato! They have their own yam family (Dioscoreaceae). Most are tropical species, some are commonly used as food in the Caribbean and tropical Africa (available only in specialty stores throughout much of the US). They are represented locally by wild yam (Dioscorea villosa), a charming climbing vine with attractive heart-shaped leaves and three-winged seed pods. The roots of wild yam are small tubers, they are edible, and the plant is preported to have medicinal properties.

Wild yam. Photo courtesy Chris Noll.

True potatoes are in nightshade family (Solanaceae). They are in the genus Solanum along with tomatoes (both from South America) and a few local weeds including black nightshade and deadly nightshade (both from Eurasia). Chili peppers are also a member of often tasty, but sometimes poisonous family and also of American origin.
Deadly nightshade, not actually deadly, but not good for you either.

So there's something to talk about with your fellow plant nerds over the holidays!