Which type of foliage offers visual strength and enhances the line of floral designs?

Linear foliage is characterized by its elongated shapes and forms, which create strong vertical or horizontal lines in floral arrangements. These types of foliage serve to guide the viewer's eye through the design, enhancing the overall flow and structure. By providing clear lines, linear foliage can also add a sense of dynamism and movement to the arrangement, making it visually striking.

In contrast, other types of foliage serve different purposes in floral design. For instance, mass foliage tends to be more compact and rounded, primarily used to fill space and create fullness rather than define lines. Filler foliage adds texture and small accents to designs, focusing more on filling gaps than providing structural lines. Form foliage may have a distinct shape that draws attention but does not necessarily create the kind of linear strength that enhances the overall composition in the same way as linear foliage. Thus, the primary role of linear foliage in establishing visual strength and guiding the viewer's perspective makes it the appropriate choice for this question.