A bush or shrub was a woody plant distinguished from a tree by its multiple stems and lower height, being usually less than six meters tall.
In 2267, Hikaru Sulu went to sample plants on the Shore Leave Planet, such as bushes. (TOS: "Shore Leave")
René Picard was hiding behind the bushes when he revealed himself to Jean-Luc Picard in 2367. (TNG: "Family")
In 2373, Harry Kim recalled gorging himself on overripe fruit growing on bushes. (VOY: "Coda")
In 2375, Miles O'Brien incorrectly identified the subject of his wife Keiko's paper, the Arfillian ficus, as a shrub, when, it was in fact a tree. (DS9: "What You Leave Behind")