Family tree: The life of the alder

Richard Collins says this durable tree deserves better recognition

THE Tree Council of Ireland has the gift of prophesy: it designated 2008, one of the rainiest ever recorded, as the Year of the Alder. For this tree, wetter is better. Alders love swampy places. The ‘amphibian’ of Irish trees is not well known, and so the Tree Council is giving it a PR boost. Most people can recognise an oak, or an ash, but few would know an alder, despite its wide distribution. This remarkable and useful tree deserves more respect.

The name is ancient. English, Irish, and 130 or so European and Indian languages are descended from a parent known as Indo-European, whose origins are obscure. However, some words in common use have come down to us intact from that ancient tongue. One such survivor is ‘el’, which denotes the red-brown colour of animals, such as ‘elk’, and the barks of trees, such as ‘elder’ and ‘elm’. The ‘al’ in alder may also derive from ‘el’. Although the alder’s bark is a darker brown and the chopped wood is white, the timber soon turns red or orange. The colour is so distinctive that, in Ireland, the alder is sometimes called ‘the mahogany tree’. Places such as Aldershot bear the name. The Irish, fearnóg, gave us Ferns, in Co Wexford, and, possibly, Rathfarnham, in Dublin.

It’s an easy tree to identify; the little seed-bearing cones, like those of conifers, seem out of place on a broad-leaved tree. The cones dangle from the branches throughout the winter. The drooping male catkins, about 5cm long and purple or brown in colour, appear in March. In spring and summer, the shiny leaves, sometimes sticky to the touch, are rounded rather then pointed. Indeed, there is usually a slight indentation where a point might be expected on the leaf. It’s not a long-lived tree, nor does it grow very tall; an exceptional one might reach 10 metres. An alder at Killavullen Forest, in Co Cork, grew to 13 metres in 15 years.

Strong alder roots help to consolidate river banks and prevent soil erosion. The wood won’t decay, even if submerged for long periods, and, indeed, the city of Venice owes its survival to this tree. Basilica San Marco, the Doge’s Palace, and the Rialto Bridge rest on piles of alder-wood driven into the sea bed. Sluices and pipes were made from this water-tolerant timber, but there is an archaeological mystery here. Crannógs were defensive dwellings built on artificial islands during the Irish Bronze Age, which began almost 4,000 years ago.

Alder would have been an ideal wood for such structures. Not only is it water-resistant, but it grows close to lakes everywhere in Ireland. There would have been plenty of alder timber to hand, but, apparently, it wasn’t used for crannóg building. Why? Was it deemed unlucky to cut a bush whose wood seemed to bleed by turning red? But if there were pisheógs surrounding the tree, they worked both ways; Bronze Age shields were often made from alder wood. Perhaps a blood-coloured timber was appropriate for weapons, but not for peaceful uses.

Although furniture can be made from alder wood, it’s not really a carpenter’s tree. It has, however, another useful property; it’s an excellent heat insulator. This led to an unlikely industry; the production of wooden clogs. Alder-wood footwear kept the wearer’s feet warm and snug. Holland, a country renowned for its wetlands, has a great clog tradition. A clog-making industry thrived in Wexford at the beginning of the last century.

But the tree is valuable in more subtle ways. Alder root nodules fix nitrogen from the air, generating conditions which make damp soils suitable for other trees. It’s also a good reproducer and coloniser; the flowers appear before the leaves and each cone contains numerous tiny seeds, light enough to be carried on the wind.

The alder is related to the birch, the first tree species to spread across the land when the ice retreated long ago. A similar propensity was demonstrated more recently in Dublin Bay; as the Bull Island began to develop from a sandbank in the early 19th century, the alder soon colonised the low lying area now known as ‘the Alder Marsh’.

For information on alders, see the Irish Tree Council’s website;

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