Which principle refers to using plants to relate to ground plane forms?

The principle that refers to using plants to relate to ground plane forms is grounded in the concept of "ground relation." This principle emphasizes the importance of harmonizing the spatial characteristics of plants with the underlying forms of the ground plane in landscape design. By considering how the forms and configurations of plants can complement or contrast with the terrain, designers are able to create a cohesive and visually appealing landscape. This relationship not only enhances aesthetic values but also contributes to the overall functionality of the space, as plants can help define areas, guide movement, and integrate various elements of the design.

In contrast to the other principles: proportionality focuses on the scale and ratio of elements, visual hierarchy deals with the arrangement and prioritization of visual elements in a composition, and plant selection strategy pertains to the criteria and rationale behind choosing specific plant species. While these concepts may influence aspects of landscape design, "ground relation" specifically addresses the interaction between plant forms and the shapes of the ground, making it the most applicable term in this context.