undergrowth

From Wiktionary

Word parts[change]

under- + growth

Noun[change]

Singular
undergrowth

Plural
none

These green plants are undergrowth in this forest.
  1. (uncountable) Undergrowth is smaller plants growing in a forest: bushes, which are smaller than the trees and which grow under the trees.
    She couldn't walk very fast in this forest, because she had to push through the undergrowth.