Chinese wolfberry vs boxthorn

Chinese wolfberry

noun
  • Either of two Chinese species of spiny shrub in the nightshade family, Lycium barbarum and Lycium chinense, and their edible fruits, which are used in East Asian traditional medicine. 

boxthorn

noun
  • Any plant of the genus Lycium. 

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