On Sat, 3 Feb 2007 12:04, Lynn wrote:

>Hi Ginny,
>
>So are yams edible?
>
>Sincerely,
>Lynn
>
>> Yams are Dioscoraceae
>>
>> Potatoes and sweet potatoes are Solanaceae, and share the rather
>> poisonous characteristics of the family, which includes tomatos,
>> eggplants, green peppers and chilis as well.
>>
>> ginny

Check the Wikipedia page on yams. 

http://en.wikipedia.org/wiki/Yam_(vegetable)

Seems Americans refer to 'sweet potatoes' (Ipomoea batatas) as yams. They are distantly related to 
the Solanaceae and even more distantly related to the Dioscoraceae. This ambiguity leads non-
Americans to refer to the Dioscoraceae as 'true yams' when writing for an international audience.

Sweet potatoes have been cultivated in the highlands of Papua New Guinea for around 10,000 
years by traditional palaeolithic societies. In 1973 I visited an archaeological dig at Kuk tea 
plantation in Mount Hagen where evidence for this was shown. No one has been able to explain 
convincingly how they came to be in western Melanesia so far back.
Keith