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. This trunk 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...)
Kauri gum is resin from kauri trees (Agathis australis), which historically had several important industrial uses. It can also be used to make crafts such as jewellery. Kauri forests once covered much of the North Island of New Zealand, before climate change caused the forests to retreat, causing several areas to revert to sand dunes, scrubs, and swamps. Even afterwards, ancient kauri fields and the remaining forests continued to provide a source for the gum. Between 1820 and 1900, over 90% of Kauri forests were logged or burnt by Europeans.Kauri gum forms when resin from kauri trees leaks out through fractures or cracks in the bark, hardening with the exposure to air. Lumps commonly fall to the ground and can be covered with soil and forest litter, eventually fossilising. Other lumps form as branches forked or trees are damaged, releasing the resin. (Full article...)
Did you know? -
- ... 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?
Selected article -
Quercus robur) (from Tree)Buds, leaves, flowers and fruit of oak (
Tree)Roof trusses made from softwood (from
Niepołomice Forest in Poland has had special use and protection. In this view from space, different coloration can indicate different functions. (from Forest)Since the 13th century, the
Madagascar, featuring various Adansonia (baobab) species, Alluaudia procera (Madagascar ocotillo) and other vegetation (from Forest)Spiny forest at Ifaty,
Ceiba pentandra) (from Tree)Buttress roots of the kapok tree (
herbaceous monocotyledonous plants such as banana lack secondary growth, but are trees under the broadest definition. (from Tree)Tall
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)Diagram of
Swabian alps (from Tree)Conifers in the
Adirondack Mountains of Upstate New York form the southernmost part of the Eastern forest-boreal transition ecoregion. (from Forest)The
Burned forest on Thasos (from Forest)
Latex collecting from a rubber tree (Hevea brasiliensis) (from Tree)
Yggdrasil, the World Ash of Norse mythology (from Tree)
Acer saccharum) tapped to collect sap for maple syrup (from Tree)Sugar maple (
Tree)Selling firewood at a market (from
General Sherman Tree, thought to be the world's largest by volume (from Tree)The
Tree)People trees, by Pooktre (from
Wicklow, Ireland (from List of trees of Great Britain and Ireland)Rowan tree in
Vinitsa, North Macedonia (from Forest)A forest near
Alleé of London plane trees (Platanus × acerifolia) in garden (from Tree)
Priest 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)
thorny skin of a Aesculus tree seed (from Tree)Cracked
Lepidodendron, an extinct lycophyte tree (from Tree)
Scottish Highlands (from Forest)Forest in the
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)Even, dense
Quercus suber) (from Tree)Recently stripped cork oak (
Fagus sylvatica) trunk in autumn (from Tree)Northern beech (
Abies alba) (from Tree)Buds, leaves and reproductive structures of white fir (
Fraxinus excelsior), a deciduous broad-leaved (angiosperm) tree (from Tree)Common ash (
Larix decidua), a coniferous tree which is also deciduous (from Tree)European larch (
Cypress of Abarqu is the oldest tree in Iran and the second oldest tree in the world. (from List of trees of Iran)4000 years old
Temperate rainforest in Tasmania's Hellyer Gorge (from Forest)
Cycas circinalis) (from Tree)Form, leaves and reproductive structures of queen sago (
Daintree Rainforest (from Tree)The
Pine Forest in Ķegums Municipality (from Forest)Latvian
Weeping Willow, Claude Monet, 1918 (from Tree)Trees in art:
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