There are over 600 species of oak trees. Quercus robur commonly known as pedunculate oak and Q. petraea, sessile oak are native to Ireland. While the native oaks are deciduous there are evergreen species from other parts of the world that can grow in Irish gardens. Most oaks can become very large trees and look beautiful when standing in a field or parkland. The oak is often used as a symbol of strength and resilience.
The fruit of the oak is called an acorn. Oak trees do not produce a good crop every year. When they are abundant they can be collected and ground into a flour used in baking.
The sessile oak is the main species found in Ireland, growing on poor acid soils and in hilly regions. They are very important to the ecology as native oak trees support a large and diverse range of insect, mammal and bird species.
Holm oak is an evergreen species called Q. ilex. When young the foliage resemble that of holly in shape with similar spines at the leaf margins. Leaves on mature parts of the plant have a different, smoother shape. It can be trimmed to make a dense hedge tolerant of coastal winds.
Another evergreen species, a native of the Mediterranean region is Q. suber. It is commonly known as cork oak. Its thick bark is the source of cork used for wine bottles and products such as cork tiles. It can be grown in the milder parts of Ireland without any damage from winter cold.