Persian lilac vs neem

Persian lilac

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

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

neem

noun
  • Azadirachta indica, a large, mostly evergreen tree from India, whose seeds yield the insecticide azadirachtin. 

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