They’re all around us, and are essential to our survival. Here we reveal a few facts and figures about these wonders of the natural world.
A tree is a woody plant that has a stem or trunk at the base, above which branches develop. They are divided into deciduous and evergreen.
The leaves of deciduous trees change colour in autumn because, as nights get longer and frosts arrive, the production of chlorophyll – which makes leaves green – gradually stops, and two other pigments (carotenoids – brown, orange, yellow, and anthocyanins – red, purple) come to the fore.
When a tree is cut down or burnt, all the carbon dioxide it has stored during its life is released into the atmosphere.
Trees are thirsty organisms, each taking up to 2,000 litres of water from the ground in just one year. Most of this water is then released into the air as vapour from the leaves.
The tallest tree in the UK is a Douglas fir (Pseudotsuga menziesii) in Scotland, which measures a staggering 64.6 metres in height.
The oxygen released by one mature beech tree (Fagus sylvatica) is enough to keep three people alive.
The fruits of the female maidenhair tree (Gingko biloba) give off a powerful, noxious smell in warm temperatures - best to avoid planting it in your garden...
The oldest living trees are the bristlecone pines (Pinus longaeva) growing in the White Mountains of California. The oldest ever found was discovered to be 5,100 years old after a student had cut it down. Its younger relative – aged 4,600 – is known as the Methuselah tree; its location is a closely guarded secret.
The widest known tree on the Continent is a sweet chestnut (Castanea sativa), which was found growing on Mount Etna in Sicily. Locals christened it the Castagno di Cento Cavilli (chestnut of 100 horses) because it measured 190 feet in circumference. Although still alive, it split into three several centuries ago.
The small-leaved lime, or linden (Tilia cordata), was once the principal tree in England’s forests. It has been used in many different ways; for example, rope has been woven from its bark, tea brewed with its dried flowers, and sugar made from its sap.
Ash (Fraxinus excelsior) has proved an invaluable timber for Britain’s sportsmen and women: from it come hockey sticks, billiard cues, oars, cricket stumps and rudders.
In days gone by the rowan tree (Sorbus aucuparia) was thought to be a guard against witchcraft. Nowadays, its berries are used to make jelly.
The elder (Sambucus nigra) produces flowers and fruit, which can be used to make wine, tea, syrup and jams. Fenians once believed that if you took a deep sniff of its flower you would pass into a coma, then die. It was also a common folk belief that Judas Iscariot hanged himself from an elder tree.
The sessile oak (Quercus petraea) is native to the UK. A study of a mature example found the tree to be home to 284 insect species. By comparison, a non-native sycamore had only 15.
A single birch tree (Betula) can produce up to a million seeds in just one year. Birch twigs are used to make garden brooms. Traditionally, these were used to sweep out the spirits of the old year. They are often depicted as the chosen form of transport for witches and their black cats.
In the old Gaelic alphabet each letter was symbolized by a tree, the name of which began with that letter.
The Greek name for the aspen is aspis, which means shield, and the Celts put the wood to just this use. Its Latin name (Populus tremula) alludes to the leaves’ characteristically constant movement, which produces a distinctive sound.