One of Ireland's most traditional and widely distributed trees, alders may be found in damp areas, beside freshwater loughs and along river banks, where their strong fibrous roots may help to keep the bank in place. Alder woodlands are found in Ross Island, Killarney, Co. Kerry and the Gearagh, Co. Cork, while Grantstown wood, Co. Laois is a rare example of wet woodland on an alkaline soil.
Like most trees, alder flowers before the leaves are out, with attractive reddish catkins and small cones that contain the seeds. Alder will grow in most soils, and likes wet sites. Given rich damp soil alder will grow rapidly and is a really productive tree for timber. In ancient Ireland sections of alder trunks were used as round shields. Later, it was used for making clogs and also in the furniture trade where it was known as 'Irish mahogany'. As it is resistant to decay when submerged in water, alder is used to make sluice gates and other structures along streams, rivers and canals.