Holm oak is one of the most representative trees in Spain for its special characteristics, such as its fruit, and its resistance to extreme weather conditions. The holm oak is a tree of the Fagaceae family, belonging to the order Fagales, which groups together around 670 species. Its scientific name is Quercus ilex, although it is popularly known as carrasca, chaparra or chaparro. It is characterized by a large crown, with a rounded shape, and very leafy leaves that make it an ideal tree for shade. As a whole, the holm oak can reach a height of 25 metres. The branches of the holm oak are similar to arms extended over the earth. On its branches grow showy yellowish-green unisexual flowers and evergreen leaves, i.e. they remain all year round. This tree has a wide, thick trunk with greyish cracked bark. The flowering of the holm oak usually takes place between March and May, but if the temperature reaches 20ºC it can last until June or July. One of the peculiarities of this species is that it is monoecious, that is, both sexes coexist in its flowers. Its reproduction is usually by seed, through cultivation, or by root sprouts, able to adapt easily to any type of soil. The oak fruit is the acorn. This is a dry fruit, with a single seed, which has the peculiar cascabillos at its base. Acorns are used to feed pigs, which is how the best hams are produced; but they are also fed to partridges, rabbits, ducks and wood pigeons, which travel thousands of kilometres to fetch them when they start to fall from the branches. They can also be used to make flour and bread. This fruit is usually harvested during the months of October to December. However, this tree bears fruit at 15 or 20 years of age.

In addition to its fruit, the holm oak is prized for its wood. This tree species is one of the most widely distributed on the Iberian Peninsula and the Balearic Islands. In Spain, it is estimated that this tree species occupies about three million hectares spread throughout the country. It is the most characteristic tree of the Mediterranean climate and usually grows on cool or dry soils at altitudes of up to 1,400 metres. As a special feature, this tree is resistant to drought, pollution and extreme temperatures. Holm oaks are usually kept in dehesas and their fruit is often used as feed for livestock. The forests formed by this type of tree, which is usually mixed with other species such as pine or juniper, are the best habitat for Mediterranean fauna. Like other trees, one of its essential characteristics is its contribution to the fight against climate change. Although it is not one of the most CO2 capturing trees, the adult holm oak can capture around five tonnes of CO2 per year. Holm oaks are very resilient trees and can live for many years even on land where other trees would not survive.