A hedge may consist of a single species or several, typically mixed at random. In many newly planted British hedges, at least 60 per cent of the shrubs are
hawthorn,
blackthorn, and (in the southwest)
hazel, alone or in combination. The first two are particularly effective barriers to livestock. In North America,
Maclura pomifera (i.e., hedge apple) was grown to form a barrier to exclude free-range livestock from vegetable gardens and corn fields. Other shrubs and trees used include
holly,
beech,
oak,
ash, and
willow; the last three can become very tall. Of the hedgerows in the
Normandy region of France, Martin Blumenson said, The hedgerow is a fence, half earth, half hedge. The wall at the base is a dirt parapet that varies in thickness from one to four or more feet and in height from three to twelve feet. Growing out of the wall is a hedge of hawthorn, brambles, vines, and trees, in thickness from one to three feet. Originally property demarcations, hedgerows protect crops and cattle from the ocean winds that sweep across the land. The hedgerows of
Normandy became barriers that slowed the advance of
Allied troops following the
D-Day invasion during World War II. Allied armed forces modified their
armored vehicles to facilitate breaking out of their
beachheads into the Normandy
bocage.
Species Formal, or modern garden hedges are grown in many varieties, including the following species: •
Berberis thunbergii – native to Japan and eastern Asia •
Buxus sempervirens (box) – native to western and southern Europe, northwest Africa, and southwest Asia, from southern England south to northern Morocco, and east through the northern Mediterranean region to Turkey. •
Carpinus betulus (European hornbeam) – native to Western Asia and central, eastern, and southern Europe, including southern England. •
Crataegus monogyna (hawthorn) – native to Europe, northwestern Africa, and West Asia •
Fagus sylvatica (European green beech) – native from northern Europe, in Sweden, Denmark, Norway, Germany, Poland, Switzerland, Bulgaria, eastern parts of Russia, Romania, through central Europe to France, southern England, northern Portugal, central Spain, and east to northwest Turkey where it intergrades with the oriental beech (Fagus orientalis) •
Fagus sylvatica 'Purpurea' (European purple beech) – a variant of the above •
Ilex aquifolium (European holly) – native to western and southern Europe, northwest Africa, and southwest Asia •
Ligustrum ovalifolium (privet) – native to Japan and Korea •
Ligustrum × ibolium (north privet) – native to Japan and Korea •
Photinia × fraseri (red robin) – a hybrid between
Photinia glabra and
Photinia serratifolia, native to Japan, China, Taiwan, the Philippines, Indonesia, and India, respectively •
Prunus laurocerasus (common cherry-laurel) – native to regions bordering the Black Sea in southwestern Asia and southeastern Europe, from Albania and Bulgaria east through Turkey to the Caucasus Mountains and northern Iran •
Prunus lusitanica (Portuguese cherry-laurel) – native to southwestern France, Spain, Portugal, Morocco, and Macaronesia (the Azores, Canary Islands and Madeira) •
Quercus ilex (holm oak) – native to the Mediterranean region •
Taxus baccata (yew) – native to Western Europe, Central Europe and Southern Europe (including Great Britain and Ireland), Northwest Africa, northern Iran, and Southwest Asia •
Thuja occidentalis (yellow ribbon; northern white cedar) – native to eastern Canada and much of the north-central and northeastern United States •
Thuja plicata (western red cedar) – native to the Pacific Northwest of North America
Hedgerow trees Hedgerow trees are trees that grow in hedgerows but have been allowed to reach their full height and width. There are thought to be around 1.8 million hedgerow trees in Britain (counting only those whose
canopies do not touch others) with perhaps 98% of these being in England and Wales. Many hedgerow trees are
veteran trees and therefore of great wildlife interest. The most common species are
English oak (
Quercus robur) and
ash (
Fraxinus excelsior), though in the past
field elm (
Ulmus minor 'Atinia') would also have been common. Around 20 million elm trees, most of them hedgerow trees, were felled or died through
Dutch elm disease in the late 1960s. Many other species are used, notably including
common beech (
Fagus sylvatica) and various
nut and
fruit trees. The age structure of British hedgerow trees is old because the number of new trees is not sufficient to replace the number of trees that are lost through age or disease. New trees can be established by planting but it is generally more successful to leave standard trees behind when laying hedges. Trees should be left at no closer than apart and the distances should vary so as to create a more natural landscape. The distance allows the young trees to develop full crowns without competing or producing too much shade. It is suggested that hedgerow trees cause gaps in hedges but it has been found that cutting some lower branches off lets sufficient light through to the hedge below to allow it to grow. ==Importance of hedgerows==