From the Mediterranean to the Desert

Growth in the Mediterranean forest is limited to the months of the year in which there is enough moisture and hours of light. Most of the trees have small, tough, waxy, and evergreen leaves, known as sclerophyllous leaves. They also have thick bark and gnarled, twisted branches.

In temperate regions, trees alternate periods of growth and rest with the changing of the seasons. These are recorded on the rings of the trunk, which tell us the age, size, and number of growth periods. During the spring, they are wider and lighter than during the fall.

The trunk is surrounded by the bark, which acts in a similar way to our own skin. It protects the inside of the tree, stops it from drying out, and prevents attacks by insects and fungi. Some of them are rough and grooved, like holm oaks, while others are smooth and fine, like European nettle trees and white poplars.

Branches are made of the same material as the trunk. They don't just grow at random, but follow a pattern that is sometimes related to the Fibonacci sequence. The leaves' ultimate aim is to get as much light as they can.

Mediterranean forests, such as the Science Park's Forest of the Senses (Bosque de los Sentidos), are places where migratory and local birds that have chosen it as their habitat can rest, eat, and reproduce. The provision of nest boxes, shelters, and a constant food supply makes it more likely that they will choose this place.

How do you find north if you're lost in a forest? You just need to look for lichen on the tree trunks, just like the lichen on the holm oak in the picture. Lichen needs moisture and the best place for that is in the shade, facing north, away from the sun's rays.

To cope with the high temperatures of Mediterranean summers, plants such as the ruscus reduce the size of their leaves until they are barely visible on the stem, which is often mistaken for the leaves.

Gum rockrose produces essential oils on the surface of its leaves. As well as encouraging pollination, these reduce evaporation and have a refreshing effect, similar to sweat. This is another strategy for coping with high temperatures.

Juniper is a mountain shrub that grows well in climates with cold winters, cool summers, and low rainfall. With its hard, aromatic wood and needle-shaped leaves to reduce transpiration, its fruit is round and fleshy, although not strictly a fruit.

Did you know that yew trees have been used since ancient times as both a poison and a cure? Its poison (taxine) is found throughout the tree, except for the red outer flesh of the berry (known as the aril). This is eaten by birds, which then disperse the seeds.

The Spanish fir is an Andalusian fir tree that was redistributed during the Holocene or postglacial epoch of the Quaternary period, when they were relegated to the summits of Grazalema and the Sierra de las Nieves. They have a very long lifespan of 400 to 500 years, and can grow up to around 80 feet (25 m) tall.

In these conditions, vegetation is scarce and widely dispersed and has developed physiological (behavioral) and structural adaptations that set it apart from other plants.

Some of the mechanisms to make the most of the available water include reducing the size of the leaves (or removing them altogether), having thick, impermeable surfaces, converting the stems into water stores, or being ephemeral (having a short life cycle).

In most cacti, the leaves have become spines to reduce evaporation and protect the plant from predators. The cactus in the image, known as the old man cactus, is also covered in thin, whitish hairs to protect it from the sun's intense rays.