What is the primary purpose of filler foliage in a floral arrangement?

Filler foliage plays a crucial role in floral arrangements primarily by providing volume and blending various elements seamlessly together. This type of foliage is typically used to fill in gaps between larger flowers and focal components, ensuring that the arrangement looks lush and full rather than sparse or disjointed. The filler foliage also helps to create a cohesive look by softening transitions between different flowers and elements, making the overall design more aesthetically pleasing.

While focal points are essential in guiding the viewer’s eye, and enhancing color and texture contributes to the overall beauty of an arrangement, these functions do not capture the primary role of filler foliage, which is to unify and add density to the composition. Establishing the design's line is more related to structural elements of the arrangement rather than the softening and blending role that filler foliage provides.