Portal:Trees
The Trees Portal
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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...)
Banksia serrata, commonly known as the saw banksia, the old man banksia, the saw-tooth banksia or the red honeysuckle and as wiriyagan by the Cadigal people, is a species of woody shrub or tree of the genus Banksia, in the family Proteaceae. Native to the east coast of Australia, it is found from Queensland to Victoria with outlying populations on Tasmania and Flinders Island. Commonly growing as a gnarled tree up to 16 m (50 ft) in height, it can be much smaller in more exposed areas. This Banksia species has wrinkled grey bark, shiny dark green serrated leaves and large yellow or greyish-yellow flower spikes appearing over summer. The flower spikes, or inflorescences, turn grey as they age and pollinated flowers develop into large, grey, woody seed pods called follicles.
B. serrata is one of the four original Banksia species collected by Sir Joseph Banks in 1770, and one of four species published in 1782 as part of Carolus Linnaeus the Younger's original description of the genus. There are no recognised varieties, although it is closely related to Banksia aemula. Throughout its range, it grows exclusively in sandy soil, and is usually the dominant plant in scrubland or low woodland. B. serrata is pollinated by and provides food for a wide array of vertebrate and invertebrate animals in the autumn and winter months, and is an important source of food for honeyeaters. It is a common plant of parks and gardens. (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?
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