A hedge or hedgerow is a line of shrubs and sometimes trees, planted and trained to form a barrier or to mark the boundary of an area, such as between neighbouring properties. Hedges that are used to separate a road from adjoining fields or one field from another, and are of sufficient age to incorporate larger trees, are known as hedgerows. Often they serve as windbreaks to improve conditions for the adjacent crops, as in bocage country. When clipped and maintained, hedges are also a simple form of topiary. Hedges and Hedgerows are usually no wider than about three feet.