damson vs damson plum

damson

noun
  • The edible fruit of this tree. 

  • A subspecies of plum tree, Prunus domestica subsp. insititia, native to Eurasia. 

adj
  • The color of the fruit of this tree, a very deep purple. 

damson plum

noun
  • The edible fruit of these trees. 

  • A deciduous tree, Prunus insititia, native to Eurasia and related to the plum. 

  • Chrysophyllum oliviforme, the satinleaf. 

  • Syzygium cumini, jambul, native to south Asia. 

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