Tree

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  • tree
definition
  • Any large woody perennial plant with a distinct trunk giving rise to branches or leaves at some distance from the ground.
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Abstract from DBPedia
    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 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. 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 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 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.

    樹木学（じゅもくがく、英語: Dendrology、古代ギリシア語: δένδρον, dendron, "tree"; and 古代ギリシア語: -λογία, -logia, science of or study of） or xylology （古代ギリシア語: ξύλον, ksulon, "wood"）は、木、潅木、つる植物等の木本植物を研究する学問の分野である。木本植物は多くの他の植物の科に含まれるだけではなく、これらの科は木本と草本の両方の植物から構成されている。しかし、科によってはごく少数の木本植物しか含まれない場合もあり、このことが（純粋な植物学としての）樹木学的アプローチの有用性を損なう要因にもなっている。従って、樹木学は経済的に有用な樹木の同定や園芸学、林学といった、応用的側面に重点を置く傾向がある。

    (Source: http://dbpedia.org/resource/Tree)

    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 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. 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 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 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.

    木（き）とは、 * 植物の一種を指すための用語。樹（き）、樹木（じゅもく）とも言う。木本（もくほん、植物学用語）ともいう。 * 用材や材木のこと。 「き」「木」や「樹」というのは古代から用いられてきた呼称・概念である。 現代では、「木」は高木と低木の総称であるとも、木は大きさによって高木（喬木 きょうぼく）と低木（灌木 かんぼく）に区別するとも考えられている。「木・樹」と言って、たちき（立木）を指していることもある。また「木・樹」と言って、特に高木を指す場合もある。 現代の植物学では（素朴な言葉として用いられている「木」という語を避け、学術的な用語を用いる場合）「木本植物」という用語で呼んでおり、これは「草（草本植物）」と対比する語である。 高さは、高いものではたとえばオーストラリア大陸のユーカリの一種、北米大陸のセコイアデンドロン（セコイアオスギ）のように130mほどに達するものがあり、小さいものではフッキソウやヤブコウジのような例がある。 高木が集まってできた植物社会が森林であり、地球の陸地のほぼ半分は森林で占められているものの、近年は伐採（森林破壊）が進行中である。樹木が高い密度で集まっているものを密林、まばらに生育しているものを疎林と呼ぶ。森林による植生は地球の自然環境を支えているうえ、後述するように人類は木を燃料（薪）や建築材料（木材・材木）、食料採取、落ち葉の堆肥利用、観賞（庭園・公園や盆栽）、さらに防風林、防砂林、防潮林などとして現代に至るまで利用してきた。自然の植生に頼るだけでなく、植樹・植林により有用な樹種を維持・拡大し、育った後に伐採・加工する林業も営んできた。 樹木の生育できる気候において自然状態でまったく樹木が生育しないということは珍しく、何らかの形で樹木は生育している。気候が限界を超えて寒冷な地域（南極大陸など）や乾燥した地域（オアシスを除く砂漠など）、森林限界よりさらに標高が高く単体の木も見られなくなる高山など、樹木は生育できない土地も多い。 ケッペンの気候区分においては乾燥しすぎて樹木が生育しない地帯を乾燥帯、寒冷すぎて樹木が生育しない地帯を寒帯と呼び、樹木の生育する3気候（熱帯、温帯、冷帯）と区別する。ただし、これはあくまでも降雨量と気温による区分であり、乾燥帯においては外来河川やオアシスなど、降雨によらず水分を得ることのできる地点においては樹木は生育している。また、まれに樹木が発芽し十分に発育して地下の水脈に根を到達させたのちに周囲の気候が乾燥した場合、本来全く樹木が生育できる条件がないのもかかわらず樹木が存在することとなる。こうした例で最も著名なものの一つに、アフリカのテネレ砂漠に存在したテネレの木がある。この木は地球上で最も孤立したところに立っていた木として知られ、最も近い別の木から少なくとも200㎞は離れたところに立っていた。 木は古来、人間の生活・文化と密接な関係があり、洋の東西を問わず祭祀に何らかのかかわりを持っている。

    (Source: http://dbpedia.org/resource/Tree)