Family: Fagaceae
Species: Quercus suber L.
Common name: Cork oak, Sughera - English: Cork oak - Deutsch: Korkeiche
Description
Quercus suber is an evergreen tree that can reach up to 20 metres in height and is long-lived if not exploited for cork production. The robust, sinuous trunk soon divides into irregular branches, forming an asymmetrical crown similar to the holm oak.
The bark is initially smooth and grey; with age, it thickens, becomes wrinkled, and is furrowed by deep grooves. It is light in colour on the outside but pinkish and spongy on the inside—this is the cork. When the cork bark is removed, the exposed trunk has a reddish colour that darkens as the tannins oxidise in the air.
The leaves are medium-sized and persist for 2–3 years. They are leathery and ovate-lanceolate, with either an entire or a prickly margin—sometimes with true thorns—and are folded downwards. In consistency and colour, the leaves are similar to the holm oak's. The species exhibits heteromorphism with age; in young plants or on young branches, the leaves are oval with a rather prickly margin and have sparse, scattered hairs on the upper surface, while the lower surface is green with a light tomentum. In adult plants, the upper surface becomes shiny green, and the lower surface turns greyish-white, protected by waxy substances.
The male flowers are borne on long filaments that appear at the top of the previous year’s branches, while the female flowers are grouped on a pubescent axis of spikelets on the current year’s branches.
Depending on the period of anthesis, acorn maturation occurs in autumn of the same year for spring anthesis or in late summer to early autumn of the following year for autumn anthesis. The acorn has a sub-spherical dome covered by grey, tomentose scales that extend over about half of the acorn.
Habitat
Quercus suber is native to the Mediterranean region in the strict sense—it is limited to the Mediterranean coasts (the Olive Area).
Properties and Uses
It is widely cultivated for cork production, but its fruits (acorns) are also used as food for livestock, and its wood is used as coal (the ashes are rich in potassium).
Notes and Curiosities
This extraordinary treasure of the Mediterranean is also known by the names "sughera" or "chaparro" in the Iberian Peninsula. Cork is a light material that floats, is impermeable to liquids, and does not transmit heat—qualities known to man for 2000 years. The Romans used cork to make sandals and floats for fishing nets. However, it was only when glass bottles began to be produced on a large scale (around 1400–1500) that the basis for the modern cork industry was established, as the tree can regenerate its bark multiple times as long as the living tissues immediately beneath remain undamaged.
Quercus suber is also grown as an ornamental garden shrub, as it tolerates low temperatures. It prefers full sun but adapts well to partial shade. In the Heller Botanical Garden, visitors can admire a specimen immediately behind the Malo Pond, where the bark, covered in moss, accentuates its deep grooves.