Name one characteristic of "filler" flowers.

Filler flowers are characterized by their smaller size and their primary function in floral arrangements, which is to fill empty spaces and provide visual interest without overpowering the focal flowers. Their subtle presence helps to create depth and texture in a design, allowing for a more balanced and cohesive look. While filler flowers can be colorful, their main role is not to serve as the main attraction but rather to complement and enhance the overall arrangement. This is why the correct answer emphasizes their small size and filling nature.