Topiary is an art form of training plants into different shapes and forms. Traditionally evergreen shrubs which will keep there shape throughout the year are used to form topiary. Evergreen shrubs which are commonly used for topiary are box (buxus sempervirens), japanese holly  (IIex Crenata) and yew (taxus baccata). These are all slow dense growing shrubs which help form the shape you desire. Topiary is used in formal or contemporary gardens and they area ideal to make a eye catching entrance to your home or in a structured garden where they can be place in borders surrounded by herbaceous plants.