Ilex Aquifolium, on its common name Holly is a fully hardy, evergreen shrub that can grow to form a tree of about 20 m high if left un-pruned. Through pruning holly can be maintained as a shrub and it can be used to form an impenetrable hedge. It is an ideal hedging plant for many reasons: it is slow growing - so it needs little maintenance with pruning, it is a good intruder deterrent because of its dense form and prickly leaves, its berries provide food for birds over the winter, it can be trimmed into a formal decorative hedge which provides an excellent windbreak and is also pollution resistant.