yampe vs yampee

yampe

noun
  • A reddish vegetable, a form of yam with a vine that twists from left to right, the opposite of the ordinary yam vine. 

yampee

noun
  • A variety of yam, Dioscorea trifida, smaller than a regular yam. 

How often have the words yampe and yampee occurred in a corpus of books? (source: Google Ngram Viewer )