rachis vs shrub celery

rachis

noun
  • The main shaft of either a compound leaf, head of grain, or fern frond. 

  • An anatomical shaft or axis in a marine invertebrate. 

  • The central shaft of a feather. 

shrub celery

noun
  • The crisp, thick leafstalk of the celery plant; used as a vegetable, or eaten raw. 

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