white alder vs yellow nightshade

white alder

noun

  • American winterberry (Ilex verticillata). 

  • Grey alder (Alnus incana) 

yellow nightshade

noun

  • Physalis crassifolia 

  • Solanum villosum 

How often have the words white alder and yellow nightshade occurred in a corpus of books? (source: Google Ngram Viewer )