Chinese celery vs celery

Chinese celery

noun
  • Apium graveolens var. secalinum, a variety of celery with smaller stalks and flavorful leaves, grown in East Asian countries for use in cooking. 

celery

noun
  • A European herb (Apium graveolens) of the carrot family. 

  • The stalks of this herb eaten as a vegetable. 

  • A yellow-green colour, like that of a celery. 

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