Worldwide there are 400 species of oak trees and shrubs. There are two oak trees native to Ireland and a few others that also grow there. This country is deemed the northern most latitude where these deciduous trees will grow. Oak trees have been a part of Irish culture for a very long time and the druids and ancient Celts believed that doors made of oak would keep out evil spirits. The oaks that grow in Ireland are of the White oak group, meaning that they have rounded lobes on the leaves opposed to pointed lobes like the Red oak family.
Also known as the Pedunculate oak, English oak, British oak or Truffle oak, this oak (Quercus robur) is a slow growing tree and is Galway's largest example of a native oak tree. The one there is about 88.58 feet tall and has a circumference of nearly 20 feet. This species of oak tree has leaves which are spirally arranged with the classic oak leaf lobed margins. The acorns have long stalks up to two inches in length. The twigs are pale gray and stout. The leafstalks are shorter than the American White Oak. This tree is also native to other parts of Europe and Northern Africa and is sometimes cultivated along the Northeast coast of the United States.
The sessile oak (Quercus petraea) also has spirally arranged, lobed leaves but unlike the common oak the acorns have no stalks at all. The largest Sessile oak in Ireland can be seen in Baronscourt Estate, Baronscourt, in County Tyrone, according to James Kilkelly of Irishgardeners.com. This "king" tree is more than 78 feet tall and has a circumference of 27.23 feet. Sessile oaks can also be found in Killarney National Park in County Kerry, Glen of the Downs in County Wicklow, and Glenveagh Forest Park in County Donegal. These oaks can live to be more than 300 years old and grow to more than 131 feet tall.
Other Oaks in Ireland
Though the previous two oaks are native to Ireland, there are a few others that grow there including, the Turkey oak (Quercus cerris) and holm oak (Quercus ilex). The Turkey oak, also known as the bitter oak has coarsely toothed to pinnately lobed leaves and acorns that have large deep cups with long curved scales which look spikey. The holm oak, also known as the holly oak, is actually an evergreen and is smaller than most oaks. The bark is smooth and gray and the leaves are not lobed but ovate. The acorns have caps which cover half of the nut and large nipple-shaped tips at the bottom of them.