hedge, ornamental or protective barrier composed of shrubs or small trees growing in close rows. The plants may be allowed to grow naturally or may be trimmed to various heights and shapes (see topiary work). In the temperate zone, thorny hedge plants include barberry, Osage orange, buckthorn, and hawthorn. Popular evergreen hedge plants are box, privet, azalea, yew, arborvitae, rhododendron, mountain laurel, and holly. Decorative deciduous shrubs often used are lilac, forsythia, mock orange, spiraea, euonymus, and viburnum. Hedges may also serve in erosion control, e.g., Rosa rugosa planted along highway embankments and the rows of poplars, hemlocks, and other trees planted as shelter belts.