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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.

Tree Media

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The wall of Tuan Cheng (Circular City) in Beihai Park

The wall of Tuan Cheng (Circular City) in Beihai Park

Format: Hand painted lantern slides...Rights Info: No known restrictions on publication...Part Of: Powerhouse Museum Collection..General information about the Powerhouse Museum Collection is available at www... more

Pasadena Community drive-in church: St. Petersburg, Florida

Pasadena Community drive-in church: St. Petersburg, Florida

Persistent URL: www.floridamemory.com/items/show/245088 ( http://www.floridamemory.com/items/show/245088 ) ..Local call number: JJS0180..Title: Pasadena Community drive-in church: St. Petersburg, Florida..Date:... more

Lois Duncan Steinmetz gazing at the Suwannee River

Lois Duncan Steinmetz gazing at the Suwannee River

Local call number: JJS0379..Title: Lois Duncan Steinmetz gazing at the Suwannee River..Date: 1949..Physical descrip: 1 transparency - col. - 5 x 4 in...Series Title: Joseph Janney Steinmetz Collection ( http://... more

Lekythos
Vase (Maebyong) with Clouds, Flying Cranes, and Children amid Bamboo

Vase (Maebyong) with Clouds, Flying Cranes, and Children amid Bamboo

Celadon or green-glazed stoneware is one of the greatest achievements of Korea’s Goryeo dynasty. Goryeo potters absorbed Chinese techniques and surpassed that country’s examples by further refining a technique ... more

Birds and trees from BL Royal 10 E IV, f. 33v

Birds and trees from BL Royal 10 E IV, f. 33v

Detail of a bas-de-page scene of birds and trees. Image taken from f. 33v of Decretals of Gregory IX with glossa ordinaria (the 'Smithfield Decretals'). Written in Latin.

Hermit among trees from BL Royal 10 E IV, f. 131v

Hermit among trees from BL Royal 10 E IV, f. 131v

Detail of a bas-de-page scene of a naked hermit among the trees. Image taken from f. 131v of Decretals of Gregory IX with glossa ordinaria (the 'Smithfield Decretals'). Written in Latin.

Purse
Arbores (trees) from BL Royal 6 E VI, f. 143

Arbores (trees) from BL Royal 6 E VI, f. 143

Detail of a historiated initial 'A'(rbor) of a hunter with a horn and dogs in a forest. Image taken from f. 143 of Omne Bonum (Absolucio-Circumcisio). Written in Latin.

Arbores (trees) from BL Royal 6 E VI, f. 142

Arbores (trees) from BL Royal 6 E VI, f. 142

Detail of a historiated initial 'A'(rbor) of a hunter with a horn and dogs in a forest. Image taken from f. 142 of Omne Bonum (Absolucio-Circumcisio). Written in Latin.

Vase
Plate