Quercus suber - Cork Oak

Quercus suber, more commonly known as cork oak, is an evergreen tree found in Mediterranean forests and scrub vegetation strictly limited to non-calcareous soils, unlike the holm oak, another southern oak that is much more tolerant. This medium-sized tree has been cultivated for a long time for its thick, insulating, fire-resistant, and spongy bark called cork. Its small dark-green and prickly foliage, reminiscent of holly, beautifully decorates this tree with a rounded canopy and picturesque appearance that is full of charm.

Quercus suber dominates the scrub vegetation of the island of Corsica, often mixed with holm oak. Native to the western Mediterranean, it is widespread in Portugal, Spain, Sicily, Sardinia, and Italy along the Tyrrhenian coast. In France, apart from Corsica, it is found at low altitudes always on poor, sandy, or schistous soil. It belongs to the family Fagaceae, like all oaks. At maturity, the tree will reach an average of 11 to 12 metres (36 ft 1 in to 39 ft 5 in) in all directions. Its growth is slow during the first years, moderately fast afterwards, with the plant favouring the development of its long taproot before growing above the ground. It has a good lifespan, around 300 to 400 years, especially when it is not exploited for its bark. It has a stocky habit, with a fairly short and wide trunk bearing a few spread-out main branches that support a sparse, rounded, and spread-out crown. 

The bark of this tree is thick, creviced, and swollen, dull grey to black in colour, waterproof and fire-resistant. This spontaneously produced bark is not used to make corks but is used for insulation. It will be removed from subjects intended for production, to produce another bark with even more remarkable properties, called cork. On cultivated trees, one can observe the bare, smooth trunks that are brick-red to reddish in colour. The young branches are pubescent before becoming smooth and grey. The evergreen leaves, arranged alternately, measure from 3 to 5 cm (1.2 to 2 in) in length. They are leathery, short-petioled, and edged with spiny teeth. The lamina is convex, shiny and dark-green with a slightly glaucous hue. The undersides of the leaves are lighter. Each leaf has a lifespan of 2 to 3 years and will fall in spring when new leaves emerge. Flowering occurs in April-May. Male flowers are grouped in hanging yellow catkins, while the very small female flowers are usually in pairs. After wind pollination, elongated acorns, 2 to 3 cm (0.8 to 1.2 in) long, are formed inside a scaly and tomentose cupule. They are brick-red in colour and mature in two years.

The sun-worshipping cork oak is tough enough to withstand drought and even forest fires. It fears severe frosts, however, and calcareous, heavy, and compact soils. If your soil and climate allow it, planting this tree will allow you to recreate a fragment of scrub vegetation in your garden by shaping a copse garden around its trunk. Plant it as a solitary subject or as a grove, combining perennials, shrubs, and southern trees (lavenders, Salvia, Ballota, highly fragrant Cistus ladanifer, Teucrium, Phlomis, Erica arborea, mastic, and Arbustus unedo).

Properties:

The wood, burned in covered pottery, produces a powdery and very black ash used as a pigment. Historically, it was known as "Spanish black". The wood of the cork oak, very hard and dense, is an excellent fuel for heating. It is also valued for constructing frameworks and in carpentry.