Aesculus hippocastanum vs horse chestnut

Aesculus hippocastanum

horse chestnut

noun
  • Any of several tree species of genus Aesculus, especially Aesculus hippocastanum, common in temperate northern hemisphere. 

  • The large nutlike seed of these trees. 

How often have the words Aesculus hippocastanum and horse chestnut occurred in a corpus of books? (source: Google Ngram Viewer )