Final answer:
When a gardener trims leaves from the stem of a rose, they cut the petiole, which is the stalk connecting the leaf to the stem.
Step-by-step explanation:
When a gardener trims leaves off of the stem of a rose, they are cutting the petiole. The petiole is the stalk that extends from the stem to the base of the leaf, which functions as the connection between the leaf and the stem. By cutting the petiole, the gardener effectively removes the leaf from the plant.
In a typical leaf structure, the petiole supports the leaf blade or lamina and precedes any stipules that may be present at the base. Moreover, nodes on the stem serve as points of attachment for the petioles, and the area between two nodes is known as an internode. Recognizing this structure is important for processes such as pruning or studying plant growth.