outgrowth vs wellspring

outgrowth

noun
  • An appendage of an animal. 

  • A branch or offshoot of a plant. 

  • Excessive growth. 

  • A byproduct or consequence of an action or event. 

wellspring

noun
  • A perennial source of anything; a fountainhead of supply or emanation; resource. 

  • The source of water for a stream, spring or well; a fountainhead; a wellhead. 

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