Portal:Trees
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The Trees Portal
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 have been in existence for 370 million years. It is estimated that there are around three trillion mature trees in the world.
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 it 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. Flowers and fruit may be present, but some trees, such as conifers, instead have pollen cones and seed cones. Palms, bananas, and bamboos also produce seeds, but 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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- ... that Gregory's tree (pictured), near Timber Creek in Australia's Northern Territory, bears inscriptions by 19th-century explorers and is registered as both a heritage place and an Aboriginal sacred site?
- ... that the Balderschwang Yew is possibly the oldest tree in Germany?
- ... that black truffles suppress plant growth around their host tree, creating an area that looks burned?
- ... that root extracts from the tree species Pycnanthus angolensis can be used to treat parasitic infections, such as schistosomiasis?
- ... that the lime trees of Duncliffe Wood are reputedly among the oldest living things in the county of Dorset?
- ... that trees of the New Guinea genus Finschia have stilt roots coming off the trunk up to 1.8 m (6 ft) off the ground?
- ... that in the early 1980s, a team of surveyors discovered the World War II-era Avro Anson Memorial near Clackline, Western Australia, which had been overgrown by shrubs and trees?
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Fraxinus (/ˈfræksɪnəs/), commonly called ash, is a genus of plants in the olive and lilac family, Oleaceae, and comprises 45–65 species of usually medium-to-large trees, most of which are deciduous trees, although some subtropical species are evergreen trees. The genus is widespread throughout much of Europe, Asia, and North America.
The leaves are opposite (rarely in whorls of three), and mostly pinnately compound, though simple in a few species. The seeds, popularly known as "keys" or "helicopter seeds", are a type of fruit known as a samara. Some Fraxinus species are dioecious, having male and female flowers on separate plants but sex in ash is expressed as a continuum between male and female individuals, dominated by unisexual trees. With age, ash may change their sexual function from predominantly male and hermaphrodite towards femaleness ; if grown as an ornamental and both sexes are present, ashes can cause a considerable litter problem with their seeds. Rowans or mountain ashes have leaves and buds superficially similar to those of true ashes, but belong to the unrelated genus Sorbus in the rose family. (Full article...)General images
- Image 4Share of land that is covered by forest (from Forest)
- Image 11Selling firewood at a market (from Tree)
- Image 15Olive trees in Pakistan (from Trees of Pakistan)
- Image 16Roof trusses made from softwood (from Tree)
- Image 22Share of forest area in total land area, top countries (2021) (from Forest)
- Image 23Tall herbaceous monocotyledonous plants such as banana lack secondary growth, but are trees under the broadest definition. (from Tree)
- Image 24Even, 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 29Since 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 344000 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 35The Amazon rainforest alongside the Solimões River, a tropical rainforest. These forests are the most biodiverse and productive ecosystems in the world. (from Forest)
- Image 37Proportion of forest in protected areas, by region, 2020 (from Forest)
- Image 42World production of selected forest products (from Forest)
- Image 47Spiny forest at Ifaty, Madagascar, featuring various Adansonia (baobab) species, Alluaudia procera (Madagascar ocotillo) and other vegetation (from Forest)
- Image 49Diagram 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 51Proportion and distribution of global forest area by climatic domain, 2020 (from Forest)
- Image 53Priest 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 54People trees, by Pooktre (from Tree)
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