In the modern Irish farm landscape the land is parcelled out into fields which are bounded by either stone walls or hedges.
Dry stone walls, such as those found in the Mourne Mountains or parts of Co Down, support little or no plant life except bryophytes and lichens. Mortared stone walls can be very rich in plants and there are several species which are characteristic of such walls
The majority of hedgerows in Northern Ireland are of comparatively recent origin - probably mid-nineteenth century. Frequently they consist of an earth bank, faced with stones on one side and with hawthorn planted between the stones at the time of construction. The construction of the earth bank often resulted in a corresponding linear depression or ditch which runs parallel to the base of the bank. This ditch is frequently damp or carries a small stream.
This type of field boundary can be rich in plant species. The commonest hedging shrubs used were hawthorn (Crataegus monogyna and sometimes Crataegus x macrocarpa) and blackthorn (Prunus spinosa). But other species of shrub were occasionally used such as Japanese Privet (Ligustrum ovalifolium) in parts of south-east Co Antrim, laburnum (Laburnum x watereri) in south Co Londonderry, wild plum (Prunus domestica) around orchards in Co Armagh, and fuchsia (Fuchsia magellanica) near the coasts. With the passage of time, various other shrub and tree species invade and establish themselves in hedges, or sometimes were planted locally. The most frequently encountered of these include:
|Brambles||Rubus fruticosus agg.|
|Roses||Rosa canina, R. pimpinellifolia, R. sherardii, Rosa arvensis etc.|
In below the trees and shrubs, on the hedge banks, are a variety of herbaceous species, some of which are characteristic of woodland. The most characteristic herbaceous plants of hedgebanks include:
|Wood sorrel||Oxalis acetosella|
|Wood anemone||Anemone nemorosa|
|Cuckoo pint||Arum maculatum|
|Herb Robert||Geranium robertianum|
|Early purple orchid||Orchis mascula|
|Greater stitchwort||Stellaria holostea|
|Hedge parsley||Anthriscus sylvestris|
|Scaly male-fern||Dryopteris affinis|
|Soft shield-fern||Polystichum setiferum|
Hedges of whin (Ulex europaeus) can be seen in many places. These have formed naturally by the whin colonising an unplanted bank, or invading the gaps in a poorly maintained hawthorn hedge.
In about 1971 Dr Max Hooper pioneered a method of dating hedges to the nearest 100 years by relating the number of woody species in a hedge to its age. This method, while it appears to work in the southern half of England where ancient hedges are frequent, cannot be used in Northern Ireland because the vast majority of hedges are only about 250 - 150 years old.
Hedges can sometimes be dated by reference to old maps, estate records etc.
Robinson, Philip (1977), The spread of hedged enclosure in Ulster. Ulster Folklife vol. 23 pp.57-69