Sweet potato

I believe this is a japanese sweet potato from El Cerrito Natural Grocery but I can't be certain, as it's been languishing in the corner of our kitchen for many weeks. Since it managed all this growth in such an inhospitable environment, I expect great things now that I have tucked it into a nice section of the garden bed. 

As I was planting this, a neighbor walked by and remarked, "Sweet." Yes indeed.