Species: Quercus robur
Common names: oak, English oak, French oak Swedish name: ek, vanlig ek
Quercus is a genus of about 600 species of deciduous or evergreen trees and shrubs. Many deciduous species are marcescent, not dropping dead leaves until spring.They are native in the Northern Hemisphere extending from cool temperate to tropical areas. Many species are important as lumber and for wood production. Two species Q. robur and Q. petraea are domestic in Sweden. The two North American species, Q. rubra (red oak) and Q. palustris (pin oak), are cultivated and quite common in Swedish cities and parks. Maybe the most famous Quercus is the cork oak Q. suber which bark is used in the production of corks (wine stoppers).
The oaks have many uses and a historical interest. The wood was used in the construction of ships (from Viking longships to naval warships) and buildings. Today the oak is most used in furniture, home decoration and flooring. Barrels of oak are used in the production of fine liquors like wine and bourbon. In which the beverage is stored and aged. Oak wood chips are used when smoking food like fish, cheese and meat.
The fruit is a nut called an acorn, borne in a cup-like structure known as a cupule; each acorn contains one seed (rarely two or three) and takes several months to mature. The acorn is characteristic for the genus Quercus but they look different between species. Acorns are also edible to humans in processed form, after leaching of the tannins.
Description: Quercus robur is a significant large tree reaching an age of about 1000 years. The crown is wide and the branches reach almost horizontal from the stem. The bark is rough and knobbly. The spieces epithet robur is derived from the Latin robustus meaning strong and hard. Which alludes to the trees massive growth and dense wood. In spring, a single individual produces both male flowers (in the form of catkins) and small female flowers. Quercus robur drops its leaves in the autumn.
How to grow: Quercus robur like most oaks prefers a slightly chalky, loamy and moist soil. Full sun and not too windy. It is best grown as a solitaire or in spaced groups. Some varieties are useful as avenue trees.
A tree may just be a tree to many people. But there is much to learn. If we take our time to study a tree closely we will find it crawling with life. Oaks are no exception rather good examples of trees with high biodiversity – sustaining many other species in nature.
At high age the oaks start to wither inside and becomes hollow. Insects and small animals gain from this. The murky wood sustains more than 500 species of insects many of them directly dependent on old oaks. Oaks play a critical role in the ecological community being keystone species, which means they have large effect on their environment relative to their abundance. In a wide range of habitats oak trees are important components of hardwood forests, and certain species are particularly known to grow in associations with members of the Ericaceae in oak-heath forests. A number of kinds of truffles have symbiotic relationships with oak trees. The European pied flycatchers (Ficedula hypoleuca) is an example of an animal species that often depends upon oaks. Acorns are a vital part of the forage consumed by wildlife, including squirrels.
Many species of oaks are under threat of extinction in the wild, largely due to land use changes, livestock grazing, unsustainable harvesting and climate change.
- Ecology – a woodland ecosystem at BBC.co.uk. Do not miss the informative picture showing the complex system of the life web/community in an oak.