Hottentot fig vs sour fig

Hottentot fig

noun

  • Carpobrotus edulis, a South African plant. 

  • The acidic edible fruit of this plant. 

sour fig

noun

  • Carpobrotus edulis, a creeping plant of South Africa with edible fruit. 

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