Fruit and Nut

The oaks comprise a large genus of approximately 500 species of trees and shrubs, distributed across the northern hemisphere from tropical latitudes to cold temperate and sub-arctic regions. Throughout human history acorns have probably been eaten by indigenous people, and were highly prized by many hunter-gatherer cultures.

In North America, it is well documented that acorns were used as a staple food by indigenous people. Often, the annual acorn harvest was a major cultural event. In the Mediterranean regions of Europe and the Near East, acorns were also an important food. Dried and roasted, acorns can be used to make flour. The nutrient content of acorns is similar to that of chestnuts. Acorns contain varying amounts of tannin, which in high doses is detrimental to human health. Generally, the acorns most prized were those from the oak species with the lowest tannin content. The tannin content can be significantly reduced by soaking the acorns then draining off the water, repeating the process as many times as necessary.

Within Europe, two evergreen oaks, namely the Holm oak (Quercus ilex) and the Cork oak (Quercus suber), have a low tannin content and an agreeable taste. Both have been used as human food until recent times. In many Mediterranean countries - both European and North African - oak woods are still highly valued and are used for grazing pigs, sheep and cows. In many cases the same carefully-balanced system of woodland management and livestock grazing has been practiced for hundreds of years. The most well-known of these is the Spanish dehesas. In Portugal the evergreen oaklands are called montados, while the Moroccans use the word azaghar.

Indigenous woodlands of the Cork oak can be found throughout the western Mediterranean and also along the Atlantic seaboard of Spain and Portugal. The indigenous Holm oak is found mainly in the Western Mediterranean and Iberia, but its range extends east as far as Greece and northwards to western France. Both oaks have been cultivated much further north. They were introduced to England in the16th century. They are perfectly hardy in coastal regions of Ireland, but the both are vulnerable to severe frosts (especially the Cork oak). For this reason, the Cork oak is unsuitable for colder inland locations.

Winter minimum temperatures

The Cork oak is considered hardy to about -8°C. Temperatures below this almost never occur in coastal areas, and would also be very rare in inland locations close to large bodies of water. The Holm oak is hardy to about -15°C. Some specimens in Ireland were apparently killed by the unusually low temperatures of December 2010.

Holm Oak (Quercus ilex)                                        
The principal oak used for human food in the Mediterranean area and in Iberia. Evergreen. Very long lived tree, fully hardy in most parts of Ireland. Will produce first acorns at about ten years. In stock

Cork Oak (Quercus suber )                                        
Highly prized in Portugal and the Western Mediterranean for its thick cork bark, long used in production of bottle stoppers, buoyancy devices, floor tiles, insulation and many other products. Evergreen. Acorns smaller than Quercus ilex. Hardy in coastal parts of Ireland. Will produce first acorns at about ten years. Unavailable at present