In botany, a tree is a perennial plant with an elongated stem, or trunk, supporting branches and leaves in most species. 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 taxonomic group but include a variety of plant species that have independently evolved a trunk and branches as a way to tower above other plants to compete for sunlight. 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 some 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 parts 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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The Mingo Oak (also known as the Mingo White Oak) was a white oak (Quercus alba) in the U.S. state of West Virginia. First recognized for its age and size in 1931, the Mingo Oak was the oldest and largest living white oak tree in the world until its death in 1938.
The Mingo Oak stood in Mingo County
, West Virginia, in a cove
at the base of Trace Mountain near the headwaters of the Trace Fork of Pigeon Creek, a tributary stream of Tug Fork
. The tree reached a height of over 200 feet (61 m), and its trunk
was 145 feet (44 m) in height. Its crown
measured 130 feet (40 m) in diameter
and 60 feet (18 m) in height. The tree's trunk measured 9 feet 10 inches (3.00 m) in diameter and the circumference
of its base measured 30 feet 9 inches (9.37 m). Assessments of its potential board lumber
ranged from 15,000 feet (4,600 m) to 40,000 feet (12,000 m). Following the tree's felling
in 1938, it was estimated to weigh approximately 5,400 long tons (5,500 t). (Full article...
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The almond (Prunus dulcis, syn. Prunus amygdalus) is a species of tree native to Iran and surrounding countries but widely cultivated elsewhere. The almond is also the name of the edible and widely cultivated seed of this tree. Within the genus Prunus, it is classified with the peach in the subgenus Amygdalus, distinguished from the other subgenera by corrugations on the shell (endocarp) surrounding the seed.
The fruit of the almond is a drupe
, consisting of an outer hull and a hard shell with the seed, which is not a true nut
, inside. Shelling almonds refers to removing the shell to reveal the seed. Almonds are sold shelled or unshelled. Blanched
almonds are shelled almonds that have been treated with hot water to soften the seedcoat
, which is then removed to reveal the white embryo
. (Full article...
The following are images from various tree-related articles on Wikipedia.
Roof trusses made from softwood
A section of yew (Taxus baccata) showing 27 annual growth rings, pale sapwood and dark heartwood
Palms and cycads as they might have appeared in the middle Tertiary
Diagram 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.
Proportion and distribution of global forest area by climatic domain, 2020
Redwood tree in northern California redwood forest, where many redwood trees are managed for preservation and longevity, rather than being harvested for wood production
Buds, leaves and reproductive structures of white fir (Abies alba)
Selling firewood at a market
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
Since 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.
Proportion of forest in protected areas, by region, 2020
A young red pine (Pinus resinosa) with spread of roots visible, as a result of soil erosion