In article ,
Phred wrote:

One of the local supermarkets has recently been flogging another type
of yam and, judging by how clean the things are, I suspect they might
actually be edible aerial tubers in this case. Pale buff skin and
pure white flesh with even a suggestion of translucence. The texture
is light and crisp -- rather "refreshing" eaten raw, but bugger all
flavour. (Rather like the tubers of _Pachyrhizus tuberosa_ in fact.)

Could be jicama, P. erosus, which is in the Fabaceae, or maybe P.erosus
is really P.tuberosus, with the error propagated around the web. At any
rate it's a popular vegetable in Mexico and adjacent parts of the US and
answers this description, especially if it's sort of vertically flattened.
Recently it's become popular as a salad ingredient in California new
cuisine, so the yuppies are creating a demand for it, and it's in all the
supermarkets here.

There seem to be a lot of Dioscorea yam cultivars. I don't know if they
are all D.batatas. There are a lot of people in Toronto from the West
Indies and Central America, and the supermarkets carry yams of many types
and colors. All the ones I've seem have been sort of rough and shaggy,
not smooth as you describe. There are probably culinary differences since
stores normally carry several kinds if they carry any.