Drought tolerant hedging, clipped shrubs
In Parque de La Paloma (Benalmadena in Spain) large open spaces of green were created by planting Pyracantha in solid blocks, an alternative to the lawns needed in public gardens. The plants rise and fall creating a dense green wave-like surface, punctuated by tight little valley paths required for the gardeners to gain access to cut them. What looks like a hedge from one side, is in fact a flowing elevated lawn on the other, a clever, cooling, solution to cover the parched earth underneath.
Many of the mediterranean shrub species (Myrtus, Pittospurnum, Teucrium and Biiter Orange - Citrus × aurantium) make excellent hedges or can be clipped and trained to produce an almost solid wall of greenery throughout the year - without irrigation.