Persian lilac vs azedarach

Persian lilac

noun
  • Syringa × persica, a shrub in the olive family (Oleaceae) 

  • Melia azedarach, a tree in the mahogany family (Meliaceae) 

azedarach

noun
  • The bark of the roots of the azedarach, used as a cathartic and emetic 

  • An Asiatic tree (Melia azedarach), common in the southern United States, commonly called bead tree, chinaberry, etc. 

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