box thorn vs wolfberry

box thorn

wolfberry

noun
  • Any of flowering species of the genus Lycium. 

  • Lycium barbarum or Lycium chinense 

  • The berry of this plant. 

  • The western snowberry, Symphoricarpos occidentalis, a shrub native to nothern and central North America. 

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