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. 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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Postcard of the tree from the 1930s or 1940s

The Tree That Owns Itself is a white oak tree that, according to legend, has legal ownership of itself and of all land within eight feet (2.4 m) of its base. Also known as the Jackson Oak, the tree is at the corner of South Finley and Dearing Streets in Athens, Georgia, US. The original tree, thought to have started life between the mid-16th and late 18th century, fell in 1942, but a new tree was grown from one of its acorns and planted in the same location. The current tree is sometimes referred to as the Son of the Tree That Owns Itself. Both trees have appeared in numerous national publications, and the site is a local landmark. (Full article...)

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... that veneration of the Amla tree (pictured), in particular on Amalaka Ekadashi, is due to the belief that the god Vishnu resides in and near the tree?
... that the future of the tropical tree Milicia regia for timber production is threatened by a gall fly, Phytolyma lata?
... that the churchyard of All Saints Church, Ulcombe in England contains a yew tree claimed to be more than 2,000 years old?
... that seeds of the extinct tree Eucommia eocenica have been found with latex covered fossils?
... that the fruits of the Lecythis ampla tree resemble little wooden pots with lids?
... that fossilized seeds of the extinct tree Eucommia montana are found from British Columbia to Colorado?
... that the Australian tree Agathis atropurpurea is known as the black kauri or the blue kauri because of the colour of its bark?

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Fraxinus ornus
1862 illustration

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...)

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General images

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

Image 1Share of land that is covered by forest (from Forest)
Image 2Rowan tree in Wicklow, Ireland (from List of trees of Great Britain and Ireland)
Image 3The Amazon rainforest alongside the Solimões River, a tropical rainforest. These forests are the most biodiverse and productive ecosystems in the world. (from Forest)
Image 4A young red pine (Pinus resinosa) with spread of roots visible, as a result of soil erosion (from Tree)
Image 5Alnus glutinosa (from List of trees of Great Britain and Ireland)
Image 6The Daintree Rainforest (from Tree)
Image 7Yggdrasil, the World Ash of Norse mythology (from Tree)
Image 8Latex collecting from a rubber tree (Hevea brasiliensis) (from Tree)
Image 9Lepidodendron, an extinct lycophyte tree (from Tree)
Image 10Northern beech (Fagus sylvatica) trunk in autumn (from Tree)
Image 11Forest in the Scottish Highlands (from Forest)
Image 12Even, 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 13European larch (Larix decidua), a coniferous tree which is also deciduous (from Tree)
Image 14Share of forest area in total land area, top countries (2021) (from Forest)
Image 15Dormant Magnolia bud (from Tree)
Image 16Informal upright style of bonsai on a juniper tree (from Tree)
Image 17Fraxinus excelsior (from List of trees of Great Britain and Ireland)
Image 18Malus sylvestris (from List of trees of Great Britain and Ireland)
Image 19The General Sherman Tree, thought to be the world's largest by volume (from Tree)
Image 20Temperate rainforest in Tasmania's Hellyer Gorge (from Forest)
Image 21Recently stripped cork oak (Quercus suber) (from Tree)
Image 22Sugar maple (Acer saccharum) tapped to collect sap for maple syrup (from Tree)
Image 23Redwood 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 244000 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 25World production of selected forest products (from Forest)
Image 26Tall herbaceous monocotyledonous plants such as banana lack secondary growth, but are trees under the broadest definition. (from Tree)
Image 27Buds, leaves and reproductive structures of white fir (Abies alba) (from Tree)
Image 28Cracked thorny skin of a Aesculus tree seed (from Tree)
Image 29Proportion of forest in protected areas, by region, 2020 (from Forest)
Image 30Buds, leaves, flowers and fruit of oak (Quercus robur) (from Tree)
Image 31Conifers in the Swabian alps (from Tree)
Image 32Form, leaves and reproductive structures of queen sago (Cycas circinalis) (from Tree)
Image 33Palms and cycads as they might have appeared in the middle Tertiary (from Tree)
Image 34Diagram 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 35Roof trusses made from softwood (from Tree)
Image 36Broadleaf forest in Bhutan (from Forest)
Image 37Garibaldi Provincial Park, British Columbia (from Forest)
Image 38Olive trees in Pakistan (from Trees of Pakistan)
Image 39Wind dispersed seed of elm (Ulmus), ash (Fraxinus) and maple (Acer) (from Tree)
Image 40Spiny forest at Ifaty, Madagascar, featuring various Adansonia (baobab) species, Alluaudia procera (Madagascar ocotillo) and other vegetation (from Forest)
Image 41Burned forest on Thasos (from Forest)
Image 42Common ash (Fraxinus excelsior), a deciduous broad-leaved (angiosperm) tree (from Tree)
Image 43Neem tree at Sant Nenuram Ashram (from Trees of Pakistan)
Image 44A forest near Vinitsa, North Macedonia (from Forest)
Image 45Latvian Pine Forest in Ķegums Municipality (from Forest)
Image 46Alleé of London plane trees (Platanus × acerifolia) in garden (from Tree)
Image 47Buttress roots of the kapok tree (Ceiba pentandra) (from Tree)
Image 48Selling firewood at a market (from Tree)
Image 49A section of yew (Taxus baccata) showing 27 annual growth rings, pale sapwood and dark heartwood (from Tree)
Image 50Since 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 51People trees, by Pooktre (from Tree)
Image 52Proportion 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 54Trees in art: Weeping Willow, Claude Monet, 1918 (from Tree)