To get a beautiful flower design or an arrangement, you don't need to show all of these three. The most important here is that your design has ornamental flowers; you will still get a terrific and an artistic flower arrangement.
Line direction is where flowers placed in the design giving the arrangement vertical direction, horizontal direction, or a diagonal line. Line materials also place curves into the flower design. Without line in a design, we would not have any fluid movement. Our eyes would be stuck and not circulate throughout the design to see the whole image we are trying to create.