The cork oak is a large tree that can reach 25 meters, has a wide and rounded crown and its bark is cork. If it is removed, it shows a reddish trunk that gradually darkens. The leaves are simple, persistent, alternate, oval or rounded, dark green on the upper side, whitish on the underside, with entire margins or in smooth spikes that do not prickle as in the holm oak. The flowers come out in hanging and yellowish peduncles in spring (catkins). Acorns are usually bitter and have a husk with protruding and soft scales. It is a typically Mediterranean tree that forms forests or appears mixed with other species of similar ecology. It grows from sea level to about 1000 m, provided the soils are acidic or devoid of lime. It needs more moisture than holm oak and bears worse frost. It lives in the western Mediterranean region. In the Iberian Peninsula it is mainly distributed in the south-western quadrant, with its best populations in central and southern Portugal. They live between 150 and 250 years although there are cork oaks dating back more than five hundred years. Quercus was the Roman name for oaks in general and for their wood, and by extension for all trees that produce acorns. Acorns are used by a wide variety of animals for food, from non-migratory animals to cranes in winter. The origin of the word is Celtic and means ‘beautiful tree’. The main use of cork oaks is that of their outer bark or cork, used for many purposes, from stoppers and insulators of all kinds to the manufacture of clothing and footwear. This is an important economic alternative in many rural areas with cork farms.