Portal:Trees

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In botany, a tree is a perennial plant with an elongated stem, or trunk, usually supporting branches and leaves. In some usages, the definition of a tree may be narrower, including only woody plants with secondary growth, plants that are usable as lumber or plants above a specified height. In wider definitions, the taller palms, tree ferns, bananas, and bamboos are also trees.

Trees are not a monophyletic taxonomic group but consist of a wide variety of plant species that have independently evolved a trunk and branches as a way to tower above other plants to compete for sunlight. The majority of tree species are angiosperms or hardwoods; of the rest, many are gymnosperms or softwoods. Trees tend to be long-lived, some reaching several thousand years old. Trees evolved around 370 million years ago, and it is estimated that there are around three trillion mature trees in the world currently.

A tree typically has many secondary branches supported clear of the ground by the trunk, which typically contains woody tissue for strength, and vascular tissue to carry materials from one part of the tree to another. For most trees the trunk is surrounded by a layer of bark which serves as a protective barrier. Below the ground, the roots branch and spread out widely; they serve to anchor the tree and extract moisture and nutrients from the soil. Above ground, the branches divide into smaller branches and shoots. The shoots typically bear leaves, which capture light energy and convert it into sugars by photosynthesis, providing the food for the tree's growth and development.

Trees usually reproduce using seeds. Flowering plants have their seeds inside fruits, while conifers carry their seeds in cones, and tree ferns produce spores instead.

Trees play a significant role in reducing erosion and moderating the climate. They remove carbon dioxide from the atmosphere and store large quantities of carbon in their tissues. Trees and forests provide a habitat for many species of animals and plants. Tropical rainforests are among the most biodiverse habitats in the world. Trees provide shade and shelter, timber for construction, fuel for cooking and heating, and fruit for food as well as having many other uses. In much of the world, forests are shrinking as trees are cleared to increase the amount of land available for agriculture. Because of their longevity and usefulness, trees have always been revered, with sacred groves in various cultures, and they play a role in many of the world's mythologies. (Full article...)

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The United Kingdom, being in the British Isles, is ideal for tree growth, thanks to its mild winters, plentiful rainfall, fertile soil and hill-sheltered topography. In the absence of people, much of Great Britain would be covered with mature oaks as well as savannah-type of plains, except for Scotland. Although conditions for forestry are good, trees face threats from fungi, parasites and pests. Nowadays, about 13% of Britain's land surface is wooded. European countries average 39%, but this varies widely from 1% (Malta) to 66% (Finland). As of 2021, government plans call for 30,000 hectares to be reforested each year.^{[needs update]} Efforts to reach these targets have attracted criticism for planting non-native trees, or trees that are out of place for their surroundings, leading to ecological changes.

The UK's supply of timber was depleted during the First and Second World Wars, when imports were difficult, and the forested area bottomed out at under 5% of Britain's land surface in 1919. That year, the Forestry Commission was established to produce a strategic reserve of timber. (Full article...)

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... that fossil leaves almost identical to those of the Australian rainforest tree Orites excelsus (pictured) have been found in New Zealand?
... that more than 8000 trees were planted in Backmuir Wood to celebrate the 2000 millennium?
... that the name of the newly defined genus of macadamia-like trees, Lasjia, is derived from the initials of Lawrence Alexander Sidney Johnson?
... that at St Athan, a wild fig tree grew out of the cement of the East Orchard chapel walls?
... that in the churchyard of St Mary and St Peter's Church in Wilmington, East Sussex, there is a 1,600-year-old, 23-foot (7 m) wide yew tree?
... that Christopher Werner made a lifelike South Carolina Palmetto tree out of iron, copper, and brass?
... that seed from an endangered Chrysophyllum imperiale tree planted in Royal Botanic Gardens, Sydney in 1868 by Prince Alfred has been sent to its native Brazil to aid in recovering the species there?

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A branch collar is the "shoulder" between the branch and trunk of woody plants; the inflammation formed at the base of the branch is caused by annually overlapping trunk tissue. The shape of the branch collar is due to two separate growth patterns, initially the branch grows basipetally, followed by seasonal trunk growth which envelops the branch.

Branch collars serve as a strong foundation to the branch, and its orientation and internal characteristics allow the branch to withstand stress from numerous directions. Functionally the branch collars also influence the conductivity of nutrients and growth patterns. (Full article...)

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General images

The following are images from various tree-related articles on Wikipedia.

Image 1Even, dense old-growth stand of beech trees (Fagus sylvatica) prepared to be regenerated by their saplings in the understory, in the Brussels part of the Sonian Forest. (from Forest)
Image 2European larch (Larix decidua), a coniferous tree which is also deciduous (from Tree)
Image 3Since the 13th century, the Niepołomice Forest in Poland has had special use and protection. In this view from space, different coloration can indicate different functions. (from Forest)
Image 4Burned forest on Thasos (from Forest)
Image 5Buttress roots of the kapok tree (Ceiba pentandra) (from Tree)
Image 6Sugar maple (Acer saccharum) tapped to collect sap for maple syrup (from Tree)
Image 7Recently stripped cork oak (Quercus suber) (from Tree)
Image 8The Amazon rainforest alongside the Solimões River, a tropical rainforest. These forests are the most biodiverse and productive ecosystems in the world. (from Forest)
Image 9Buds, leaves and reproductive structures of white fir, Abies alba (from Tree)
Image 10Proportion and distribution of global forest area by climatic domain, 2020 (from Forest)
Image 11Olive trees in Pakistan (from Trees of Pakistan)
Image 12Buds, leaves, flowers and fruit of pedunculate oak, Quercus robur (from Tree)
Image 13Priest River winding through Whitetail Butte with lots of forestry to the east—these lot patterns have existed since the mid-19th century. The white patches reflect areas with younger, smaller trees, where winter snow cover shows up brightly to the astronauts. Dark green-brown squares are parcels (from Forest)
Image 14Tall herbaceous monocotyledonous plants such as banana lack secondary growth, but are trees under the broadest definition. (from Tree)
Image 15Wind dispersed seed of elm (Ulmus), ash (Fraxinus) and maple (Acer) (from Tree)
Image 16Roof trusses made from softwood (from Tree)
Image 17Lepidodendron, an extinct lycophyte tree (from Tree)
Image 18Broadleaf forest in Bhutan (from Forest)
Image 19Share of forest area in total land area, top countries (2021) (from Forest)
Image 20Conifers in the Swabian alps (from Tree)
Image 21A forest near Vinitsa, North Macedonia (from Forest)
Image 22Selling firewood at a market (from Tree)
Image 23Casentinesi Forests, Italy (from Forest)
Image 24An avenue of London planes (Platanus × hispanica) in a garden in Belgium. (from Tree)
Image 25Garibaldi Provincial Park, British Columbia (from Forest)
Image 26A young red pine (Pinus resinosa) with spread of roots visible, as a result of soil erosion (from Tree)
Image 27Spiny forest at Ifaty, Madagascar, featuring various Adansonia (baobab) species, Alluaudia procera (Madagascar ocotillo) and other vegetation (from Forest)
Image 28Cracked thorny skin of a Aesculus tree seed (from Tree)
Image 294000 years old Cypress of Abarqu is the oldest tree in Iran and the second oldest tree in the world. (from List of trees of Iran)
Image 30Latvian Pine Forest in Ķegums Municipality (from Forest)
Image 31Proportion of forest in protected areas, by region, 2020 (from Forest)
Image 32Yggdrasil, the World Ash of Norse mythology (from Tree)
Image 33Neem tree at Sant Nenuram Ashram (from Trees of Pakistan)
Image 34Malus sylvestris (from List of trees of Great Britain and Ireland)
Image 35Common ash (Fraxinus excelsior), a deciduous broad-leaved (angiosperm) tree (from Tree)
Image 36World production of selected forest products (from Forest)
Image 37Share of land that is covered by forest (from Forest)
Image 38A section of yew (Taxus baccata) showing 27 annual growth rings, pale sapwood and dark heartwood (from Tree)
Image 39Yellow cassia, an ornamental tree with yellow flowers (from Tree)
Image 40The Daintree Rainforest (from Tree)
Image 41Rowan tree in Wicklow, Ireland (from List of trees of Great Britain and Ireland)
Image 42The General Sherman Tree, thought to be the world's largest by volume (from Tree)
Image 43Northern beech (Fagus sylvatica) trunk in autumn (from Tree)
Image 44Fraxinus excelsior (from List of trees of Great Britain and Ireland)
Image 45Informal upright style of bonsai on a juniper tree (from Tree)
Image 46Form, leaves and reproductive structures of queen sago, Cycas circinalis (from Tree)
Image 47Redwood tree in northern California redwood forest, where many redwood trees are managed for preservation and longevity, rather than being harvested for wood production (from Forest)
Image 48Diagram of secondary growth in a eudicot or coniferous tree showing idealised vertical and horizontal sections. A new layer of wood is added in each growing season, thickening the stem, existing branches and roots. (from Tree)
Image 49Trees in art: Weeping Willow, Claude Monet, 1918 (from Tree)
Image 50Dormant buds of ash, Fraxinus excelsior (from Tree)
Image 51Alnus glutinosa (from List of trees of Great Britain and Ireland)
Image 52Forest in the Scottish Highlands (from Forest)
Image 53People trees, by Pooktre (from Tree)
Image 54Temperate rainforest in Tasmania's Hellyer Gorge (from Forest)
Image 55Latex collecting from a rubber tree (Hevea brasiliensis) (from Tree)
Image 56Palms and cycads as they might have appeared in the middle Tertiary (from Tree)