coralberry vs cowberry

coralberry

noun
  • American winterberry, Ilex verticillata. 

  • Symphoricarpos orbiculatus, of eastern North America. 

  • Ardisia crenata of east Asia. 

  • A species of bromeliad, Aechmea fulgens, of Brazil, and which is often used as an ornamental plant. 

cowberry

noun
  • The berry of this shrub. 

  • A shrub native to the cool temperate areas of the Northern Hemisphere (Vaccinium vitis-idaea). 

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