The sessile oak is the broader of the two varieties of oak trees found in Ireland. Identification can be made by noting the leaves and acorns. The leaves of the sessile oak have a stem between the leaf and branch while the acorn has no stalk and attaches directly to the branch. The largest Sessile oak grows at Baronscourt Estate and has a girth of almost 27 feet. Sessile oak is the most common of the two varieties native to Ireland.
The common oak tree of Ireland is taller with less spread to the branches than the sessile oak. The common oak also has a straighter trunk, making it more valuable for lumber. The leaves of the common oak are attached closely to the branch with little stem or stalk while the acorns of the common oak have a small stem between the acorn and the branch. The largest common oak is growing at Clonbrock. The tree has a diameter of more than 20 feet.
Both the Druids and Celts had strong beliefs centered around the oak tree. The Celts believed a door made out of oak wood could ward off evil spirits and the Druids believed lightning could be diverted by carving symbols into oak trees. According to the Web site treesforlife.org, Druids also had many of their religious ceremonies in oak forests. Mistletoe is commonly found in oak groves and was considered a magical plant by the Druids possibly because of its association with the oak trees.
While both varieties of oak exist across Ireland, the common oak is most common in the woods at Abbey Leix Gardens, Charleville and St. John's Wood. The Sessile oak is more common in the woods at Killarney National Park, Glen of the Downs and Glenveagh Forest Park.
