Synonyms of undergrowth
brushBrush is an area of rough open land covered with small bushes and trees. You also use brush to refer to the bushes and trees on this land.
• a meadow of low brush and grass
scrubScrub consists of low trees and bushes, especially in an area that has very little rain.
• There is an area of scrub and woodland beside the railway.
Thesaurus for undergrowth from the Collins English Thesaurus
small trees, bushes, ferns, etc, growing beneath taller trees in a wood or forest