Certified Arborist Practice Test

The correct choice indicates a leaf arrangement where each node on the stem bears only one leaf. This single leaf per node arrangement is known as "alternate" leaf arrangement. In nature, this type of arrangement helps reduce competition for light between leaves, allowing each leaf to maximize its sunlight exposure for photosynthesis.

In contrast, the other types of arrangements feature multiple leaves at each node. For instance, "opposite" leaf arrangement consists of pairs of leaves that arise at the same level on opposite sides of the stem. "Whorled" arrangement, on the other hand, involves three or more leaves growing from a single node, creating a circular pattern around the stem. Lastly, "compound" leaves consist of multiple leaflets that share a single petiole, which is quite different from having a single leaf per node. Thus, the distinct characteristic of a single leaf per node defines the alternate arrangement effectively.