Portal:Trees
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...)
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 early settlers caused the forests to retreat, causing several areas to revert to weeds, 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 upon 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 the Easter egg tree (pictured) in Saalfeld, Thuringia, was decorated with 10,000 Easter eggs in 2012?
- ... that the Living Willow Theatre, an open air theatre constructed of living willow trees, is located near the village of Llanwrthwl and occasionally holds outdoor performances of Shakespeare?
- ... that Wollemi Stringybark, a tree that grows to 45 metres (148 ft) high northwest of Sydney, remains officially undescribed?
- ... that Linton Park in Kent, England, has an avenue of Giant Sequoia trees planted in 1864?
- ... that the Eduardo Avaroa Andean Fauna National Reserve contains a "stone tree"?
- ... that the scarlet honey myrtle, an ornamental garden shrub, is from the same genus as the punk tree?
- ... that the towers of architect Terunobu Fujimori's Lamune Onsen have pine trees planted on the apex of their roofs?
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Populus tremuloides is a deciduous tree native to cooler areas of North America, one of several species referred to by the common name aspen. It is commonly called quaking aspen, trembling aspen, American aspen, mountain or golden aspen, trembling poplar, white poplar, and popple, as well as others. The trees have tall trunks, up to 25 metres (82 feet) tall, with smooth pale bark, scarred with black. The glossy green leaves, dull beneath, become golden to yellow, rarely red, in autumn. The species often propagates through its roots to form large clonal groves originating from a shared root system. These roots are not rhizomes, as new growth develops from adventitious buds on the parent root system (the ortet).
Populus tremuloides is the most widely distributed tree in North America, being found from Canada to central Mexico. It is the defining species of the aspen parkland biome in the Prairie Provinces of Canada and extreme northwest Minnesota. (Full article...)General images
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