what is pruning in elemental

Based on the search results, "pruning" in Elemental seems to be a joke or innuendo in the movie. In one scene, two trees are seen plucking fruit from each other, and when they are caught, they claim they are "just pruning". Another scene shows two characters becoming bashful and awkwardly claiming they are "just pruning," which seems to be a clear sexual innuendo. It is unclear if there is any other meaning or context to the term "pruning" in the movie.