A row of street trees can act as a plane to help define the edge of a path. This could also be considered a line in the landscape especially if seen from above.
the spiral wall used in this small eating space acts as both a line and a plane. The wall acts as a low plane that creates a sense of enclosure or volume. The spiral line creates a sense of movement or rhythm.
Planting design is unique among the design fields because plants change over time. Not only do they change seasonally, but they grow, mature, and die like all living things. The elements and principles used in planting design are the same whether the landscape design will be traditional or water wise.
An element is a distinct unit that is a piece of a larger whole. The basic visual elements of any design include; line, plane, and volume. Other elements include color, shape/ form, space, texture, and light. These are sometimes referred to as characteristics of the basic elements of design.
Lines can create movement and direction in the landscape. The shape of the line determines how this will happen. Straight, curved, zig zag, and spiral are some examples of types of lines that have different properties and can create a specific 'feeling' or mood in the space. Lines also help define edges.
A plane has the two dimensions of length and width. Planes have a variety of characteristics. They can be solid or implied. An example of an implied line are street tree plantings. Fences, walls, trellises, and repetition of plants in a line are also examples of planes.
A volume is simply a series of planes put together. It has length, width, and height. Volume is important in understanding how to create spaces in the landscape. Volumes can be enclosed or open. The biggest mistake beginning designers often make is to see the objects in the space as separate from the space itself. It is the space that we occupy.
Principles are a set of rules or instructions on how to put together the elements to create an aesthetically pleasing landscape.
More detailed information about the principles of design can be found in the following links.
Water conservation principles of design include the traditional elements and principles of design as part of the first step in the design process but go a step further to consider additional elements. The additional elements include, efficient irrigation, appropriate plant selection, soils, turf, mulch, and maintenance.