outgrowth

Short definition from Wiktionary

Noun

1. 1
   Anything that grows out of something else: A branch or offshoot of a plant.
2. 2
   Anything that grows out of something else: An appendage of an animal.
3. 3
   Anything that grows out of something else: A byproduct or consequence of an action or event.
4. 4
   Excessive growth.