California pitcher plant vs cobra lily

California pitcher plant

noun
  • The cobra lily, Darlingtonia californica. 

cobra lily

noun
  • A carnivorous plant native to northern California and southern Oregon, Darlingtonia californica 

  • Any plant in the genus Arisaema spread in eastern Asia, eastern Africa and eastern North America 

  • The plant Chasmanthe aethiopica. 

How often have the words California pitcher plant and cobra lily occurred in a corpus of books? (source: Google Ngram Viewer )