Once widespread throughout Ireland, centuries of harvesting, with few trees being replaced, means that truly native oak can be hard to find, though there are small woods in most counties. Very often, semi-natural oak woodlands contain a proportion of birch and ash, with hazel, holly and rowan scattered throughout the understorey. Oak has been harvested for its fine timber for centuries and is much prized for its visual qualities and durability. It is commonly used in the making of furniture, for veneers and in the manufacture of casks. The male flowers of oak are borne on rather inconspicuous catkins, which come out just before the leaves, but the seeds – acorns – are far more obvious. Oak trees do not produce a good crop every year, so it is worth gathering plenty in a good year. The traditional Irish oak is the sessile oak. It is the main species to be found in Ireland’s most familiar woodlands. Sessile oak is found more commonly on poor acid soils, often in hilly regions. These woodlands can be found in Killarney, Co. Kerry, the Glen of the Downs, Co. Wicklow and Glenveagh, Co. Donegal, to name but a few. They are important ecologically as habitats for hundreds of invertebrate species along with many species of birds and mammals. Sessile means that the acorns have no stalk while those of the pedunculate oak hang from long stalks.