That is also known as Shan Yao, one of the true Yams and it is very good food.
I would grow it, it also is a medicinal and the flavor is very nice.
I first found out about this yam from a Japanese family that lived across the street from me in California.
He and I exchanged a lot of methods and techniques over a 4 year period (I even worked at his nursery for a year).
Remember the leaves oppose directly across from each other on the edible species of true yams.
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