blackthorn vs swarthaak

blackthorn

noun
  • A large shrub or small tree, Prunus spinosa, that is native to Europe, western Asia, and north Africa. It has a dark bark and bears thorns. 

  • A stick or staff taken from this tree. 

swarthaak

noun
  • An African thorn tree, Senegalia mellifera. 

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