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Tree

2007 Schools Wikipedia Selection. Related subjects: Plants

   The coniferous Coast Redwood, the tallest tree species on earth.
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   The coniferous Coast Redwood, the tallest tree species on earth.

   A tree is a large, perennial, woody plant. Though there is no set
   definition regarding minimum size, the term generally applies to plants
   at least 6 m (20 ft) high at maturity and, more important, having
   secondary branches supported on a single main stem or trunk with clear
   apical dominance (see shrub for comparison). Compared with most other
   plant forms, trees are long-lived. A few species of trees grow to 100 m
   (328 ft) tall and some can live for several thousand years.

   Trees are important components of the natural landscape due to their
   prevention of erosion and significant elements in landscaping and
   agriculture, both for their aesthetic appeal and their orchard crops
   (such as apples). Wood from trees is a common building material. Trees
   also play an intimate role in many of the world's mythologies (see
   trees in mythology).

Classification

   An oak tree in Denmark
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   An oak tree in Denmark

   A tree is a plant form that occurs in many different orders and
   families of plants. Trees thus show a wide variety of growth form, leaf
   type and shape, bark characteristics, reproductive structures, etc.

   The earliest trees were tree ferns and horsetails, which grew in vast
   forests in the Carboniferous Period; tree ferns still survive, but the
   only surviving horsetails are not of tree form. Later, in the Triassic
   Period, conifers, ginkgos, cycads and other gymnosperms appeared, and
   subsequently flowering plants in the Cretaceous Period. Most species of
   trees today are flowering plants and conifers. The listing below gives
   examples of many well-known trees and how they are typically
   classified.

   A small group of trees growing together is called a grove or copse, and
   a landscape covered by a dense growth of trees is called a forest.
   Several biotopes are defined largely by the trees that inhabit them;
   examples are rainforest and taiga (see ecozones). A landscape of trees
   scattered or spaced across grassland (usually grazed or burned over
   periodically) is called a savanna.

Morphology

   Tree roots anchor the structure and provide water and nutrients. The
   ground has eroded away around the roots of this young Pine tree.
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   Tree roots anchor the structure and provide water and nutrients. The
   ground has eroded away around the roots of this young Pine tree.

   The basic parts of a tree are the roots, trunk(s), branches, twigs and
   leaves. Tree stems consist mainly of support and transport tissues (
   xylem and phloem). Wood consists of xylem cells, and bark is made of
   phloem and other tissues external to the vascular cambium.

   Trees may be broadly grouped into exogenous and endogenous trees
   according to the way in which their stem diameter increases. Exogenous
   trees, which comprise the great majority of modern trees (all conifers,
   and all broadleaf trees), grow by the addition of new wood outwards,
   immediately under the bark. Endogenous trees, mainly in the
   monocotyledons (e.g. palms), grow by addition of new material inwards.

   As an exogenous tree grows, it creates growth rings. In temperate
   climates, these are commonly visible due to changes in the rate of
   growth with temperature variation over an annual cycle. These rings can
   be counted to determine the age of the tree, and used to date cores or
   even wood taken from trees in the past; this practice is known as the
   science of dendrochronology. In some tropical regions with constant
   year-round climate, growth is continuous and distinct rings are not
   formed, so age determination is impossible. Age determination is also
   impossible in endogenous trees.

   The roots of a tree are generally embedded in earth, providing
   anchorage for the above-ground biomass and absorbing water and
   nutrients from the soil. It should be noted, however, that while ground
   nutrients are essential to a tree's growth the majority of its biomass
   comes from carbon dioxide absorbed from the atmosphere (see
   photosynthesis). Above ground, the trunk gives height to the
   leaf-bearing branches, aiding in competition with other plant species
   for sunlight. In many trees, the arrangement of the branches optimizes
   exposure of the leaves to sunlight.

   Not all trees have all the plant organs or parts mentioned above. For
   example, most palm trees are not branched, the saguaro cactus of North
   America has no functional leaves, tree ferns do not produce bark, etc.
   Based on their general shape and size, all of these are nonetheless
   generally regarded as trees. Indeed, sometimes size is the more
   important consideration. A plant form that is similar to a tree, but
   generally having smaller, multiple trunks and/or branches that arise
   near the ground, is called a shrub. However, no sharp differentiation
   between shrubs and trees is possible. Given their small size, bonsai
   plants would not technically be 'trees', but one should not confuse
   reference to the form of a species with the size or shape of individual
   specimens. A spruce seedling does not fit the definition of a tree, but
   all spruces are trees. Bamboos by contrast, do show most of the
   characteristics of trees, yet are rarely called trees.

Champion trees

   The world's champion trees can be considered on several factors;
   height, trunk diameter or girth, total size, and age. It is significant
   that in each case, the top position is always held by a conifer, though
   a different species in each case; in most measures, the second to
   fourth places are also held by conifers.

   Tallest trees

   The heights of the tallest trees in the world have been the subject of
   considerable dispute and much (often wild) exaggeration. Modern
   verified measurement with laser rangefinders combined with tape drop
   measurements made by tree climbers, carried out by the U.S. Eastern
   Native Tree Society has shown that most older measuring methods and
   measurements are unreliable, often producing exaggerations of 5% to 15%
   above the real height. Historical claims of trees of 114 m, 117 m, 130
   m, and even 150 m, are now largely disregarded as unreliable, fantasy
   or outright fraud. The following are now accepted as the top five
   tallest reliably measured species:
    1. Coast Redwood Sequoia sempervirens: 115.55 m (378.1 ft.), Redwood
       National Park, California ( Gymnosperm Database)
    2. Coast Douglas-fir Pseudotsuga menziesii: 100.3 m (329.1 ft.),
       Brummit Creek, Coos County, Oregon ( Gymnosperm Database)
    3. Sitka Spruce Picea sitchensis: 96.7 m (317.3 ft.), Prairie Creek
       Redwoods State Park, California ( Gymnosperm Database)
    4. Giant Sequoia Sequoiadendron giganteum: 94.9 m (307.1 ft.), Redwood
       Mountain Grove, Kings Canyon National Park, California ( Gymnosperm
       Database)
    5. Australian Mountain-ash Eucalyptus regnans: 92.0 m (301.8 ft.),
       Styx Valley, Tasmania ( Forestry Tasmania [pdf file]; also
       reported, less verifiably, as 97.0 m Tasmanian Giant Trees)

   A view of a tree from below; this may exaggerate apparent height
   Enlarge
   A view of a tree from below; this may exaggerate apparent height

   Stoutest trees

   The girth ( circumference) of a tree is – or at least should be – much
   easier to measure than the height, as it is a simple matter of
   stretching a tape round the trunk, and pulling it taut to find the
   circumference. Despite this, UK tree author Alan Mitchell made the
   following comment about measurements of yew trees in the British Isles:

          "The aberrations of past measurements of yews are beyond belief.
          For example, the tree at Tisbury has a well-defined, clean, if
          irregular bole at least 1.5 m long. It has been found to have a
          girth which has dilated and shrunk in the following way: 11.28 m
          (1834 Loudon), 9.3 m (1892 Lowe), 10.67 m (1903 Elwes and
          Henry), 9.0 m (1924 E. Swanton), 9.45 m (1959 Mitchell) ....
          Earlier measurements have therefore been omitted".

   As a general standard, tree girth is taken at 'breast height'; this is
   defined differently in different situations, with most foresters
   measuring girth at 1.3 m above ground, while ornamental tree measurers
   usually measure at 1.5 m above ground; in most cases this makes little
   difference to the measured girth. On sloping ground, the "above ground"
   reference point is usually taken as the highest point on the ground
   touching the trunk, but some use the average between the highest and
   lowest points of ground. Some of the inflated old measurements may have
   been taken at ground level. Some past exaggerated measurements also
   result from measuring the complete next-to-bark measurement, pushing
   the tape in and out over every crevice and buttress.

   Modern trends are to cite the tree's diameter rather than the
   circumference; this is obtained by dividing the measured circumference
   by π; it assumes the trunk is circular in cross-section (an oval or
   irregular cross-section would result in a mean diameter slightly
   greater than the assumed circle). This is cited as dbh (diameter at
   breast height) in tree literature.

   A further problem with measuring baobabs Adansonia is that these trees
   store large amounts of water in the very soft wood in their trunks.
   This leads to marked variation in their girth over the year, swelling
   to a maximum at the end of the rainy season, minimum at the end of the
   dry season. Although baobabs have some of the highest girth
   measurements of any trees, no accurate measurements are currently
   available, but probably do not exceed 10-11 m diameter.

   The stoutest species in diameter, excluding baobabs, are:
    1. Montezuma Cypress Taxodium mucronatum: 11.42 m, Árbol del Tule,
       Santa Maria del Tule, Oaxaca, Mexico (A. F. Mitchell, International
       Dendrology Society Year Book 1983: 93, 1984).
    2. Giant Sequoia Sequoiadendron giganteum: 8.85 m, General Grant tree,
       Grant Grove, California ( Gymnosperm Database)
    3. Coast Redwood Sequoia sempervirens: 7.44 m, Prairie Creek Redwoods
       State Park, California ( Gymnosperm Database)

   Largest trees

   The largest trees in total volume are those which are both tall and of
   large diameter, and in particular, which hold a large diameter high up
   the trunk. Measurement is very complex, particularly if branch volume
   is to be included as well as the trunk volume, so measurements have
   only been made for a small number of trees, and generally only for the
   trunk. No attempt has ever been made to include root volume.

   The top four species measured so far are ( Gymnosperm Database):
    1. Giant Sequoia Sequoiadendron giganteum: 1489 m³, General Sherman
    2. Coast Redwood Sequoia sempervirens: 1045 m³, Del Norte Titan tree
    3. Western Redcedar Thuja plicata: 500 m³, Quinault Lake Redcedar
    4. Kauri Agathis australis: 400 m³, Tane Mahuta tree (total volume,
       including branches, 516.7 m³)

   However, the Alerce Fitzroya cupressoides, as yet un-measured, may well
   slot in at third or fourth place, and Montezuma Cypress Taxodium
   mucronatum is also likely to be high in the list. The largest
   angiosperm tree is an Australian Mountain-ash, the 'El Grande' tree of
   439 m³ in Tasmania ( Tasmanian Giant Trees).

   Oldest trees

   The oldest trees are determined by growth rings, which can be seen if
   the tree is cut down or in cores taken from the edge to the centre of
   the tree. Accurate determination is only possible for trees which
   produce growth rings, generally those which occur in seasonal climates;
   trees in uniform non-seasonal tropical climates grow continuously and
   do not have distinct growth rings. It is also only possible for trees
   which are solid to the centre of the tree; many very old trees become
   hollow as the dead heartwood decays away. For some of these species,
   age estimates have been made on the basis of extrapolating current
   growth rates, but the results are usually little better than guesswork
   or wild speculation.

   The verified oldest measured ages are ( Gymnosperm Database):
    1. Great Basin Bristlecone Pine Pinus longaeva: 4844 years
    2. Alerce Fitzroya cupressoides: 3622 years
    3. Giant Sequoia Sequoiadendron giganteum: 3266 years
    4. Huon-pine Lagarostrobos franklinii: 2500 years
    5. Rocky Mountains Bristlecone Pine Pinus aristata: 2435 years

   Other species suspected of reaching exceptional age include European
   Yew Taxus baccata (probably over 3000 years) and Western Redcedar Thuja
   plicata.

   The oldest verified age for an angiosperm tree is 2293 years for the
   Sri Maha Bodhi Sacred Fig (Ficus religiosa) planted in 288 BC at
   Anuradhapura, Sri Lanka; this is also the oldest human-planted tree
   with a known planting date.

Major tree genera

Flowering plants (Magnoliophyta; angiosperms)

Dicotyledons (Magnoliopsida; broadleaf or hardwood trees)

     * Altingiaceae ( Sweetgum family)
          + Sweetgum, Liquidambar species
     * Anacardiaceae ( Cashew family)
          + Cashew, Anacardium occidentale
          + Mango, Mangifera indica

   Eucalyptus niphophila in Namadgi National Park
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   Eucalyptus niphophila in Namadgi National Park
     *
          + Pistachio, Pistacia vera
          + Sumac, Rhus species
          + Lacquer tree, Toxicodendron verniciflua
     * Annonaceae ( Custard apple family)
          + Cherimoya Annona cherimola
          + Custard apple Annona reticulata
          + Pawpaw Asimina triloba
          + Soursop Annona muricata
     * Apocynaceae ( Dogbane family)
          + Pachypodium Pachypodium species
     * Aquifoliaceae ( Holly family)
          + Holly, Ilex species
     * Araliaceae ( Ivy family)
          + Kalopanax, Kalopanax pictus
            Birch tree (foreground) and maple tree (background) in fall.
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            Birch tree (foreground) and maple tree (background) in fall.
     * Betulaceae ( Birch family)
          + Alder, Alnus species
          + Birch, Betula species
          + Hornbeam, Carpinus species
          + Hazel, Corylus species
     * Bignoniaceae (family)
          + Catalpa, Catalpa species
     * Cactaceae (Cactus family)
          + Saguaro, Carnegiea gigantea
     * Cannabaceae ( Cannabis family)
          + Hackberry, Celtis species
     * Cornaceae ( Dogwood family)
          + Dogwood, Cornus species
     * Dipterocarpaceae family
          + Garjan Dipterocarpus species
          + Sal Shorea species
     * Ericaceae ( Heath family)
          + Arbutus, Arbutus species
     * Eucommiaceae ( Eucommia family)
          + Eucommia Eucommia ulmoides
     * Fabaceae (Pea family)
          + Acacia, Acacia species
          + Honey locust, Gleditsia triacanthos
          + Black locust, Robinia pseudoacacia
          + Laburnum, Laburnum species
          + Pau Brasil, Brazilwood, Caesalpinia echinata
     * Fagaceae ( Beech family )
          + Chestnut, Castanea species
          + Beech, Fagus species
          + Southern beech, Nothofagus species
          + Tanoak, Lithocarpus densiflorus
          + Oak, Quercus species
     * Fouquieriaceae ( Boojum family)
          + Boojum, Fouquieria columnaris
     * Hamamelidaceae ( Witch-hazel family)
          + Persian Ironwood, Parrotia persica
     * Juglandaceae ( Walnut family)
          + Walnut, Juglans species
          + Hickory, Carya species
          + Wingnut, Pterocarya species
     * Lauraceae ( Laurel family)
          + Cinnamon Cinnamomum zeylanicum
          + Bay Laurel Laurus nobilis
          + Avocado Persea americana
     * Lecythidaceae ( Paradise nut family)
          + Brazil Nut Bertholletia excelsa
     * Lythraceae Loosestrife family
          + Crape-myrtle Lagerstroemia species
     * Magnoliaceae ( Magnolia family)
          + Tulip tree, Liriodendron species
          + Magnolia, Magnolia species
     * Malvaceae ( Mallow family; including Tiliaceae and Bombacaceae)
       Baobab tree in South-Africa.
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       Baobab tree in South-Africa.
          + Baobab, Adansonia species
          + Silk-cotton tree, Bombax species
          + Bottletrees, Brachychiton species
          + Kapok, Ceiba pentandra
          + Durian, Durio zibethinus
          + Balsa, Ochroma lagopus
          + Cacao (cocoa), Theobroma cacao
          + Linden (Basswood, Lime), Tilia species
     * Meliaceae ( Mahogany family)
          + Neem, Azadirachta indica
          + Bead tree, Melia azedarach
          + Mahogany, Swietenia mahagoni
     * Moraceae ( Mulberry family)
       Eucalyptus bridgesiana on Red Hill, Australian Capital Territory.
       Enlarge
       Eucalyptus bridgesiana on Red Hill, Australian Capital Territory.
          + Fig, Ficus species
          + Mulberry, Morus species
     * Myristicaceae (Nutmeg family)
          + Nutmeg, Mysristica fragrans
     * Myrtaceae ( Myrtle family)
          + Eucalyptus, Eucalyptus species
          + Myrtle, Myrtus species
          + Guava, Psidium guajava
            Nyssaceae: a Dove tree in flower
            Enlarge
            Nyssaceae: a Dove tree in flower
     * Nyssaceae ( Tupelo family; sometimes included in Cornaceae)
          + Tupelo, Nyssa species
          + Dove tree, Davidia involucrata
     * Oleaceae ( Olive family)
          + Olive, Olea europaea
          + Ash, Fraxinus species
     * Paulowniaceae ( Paulownia family)
          + Foxglove Tree, Paulownia species
     * Platanaceae ( Plane family)
          + Plane, Platanus species
     * Rhizophoraceae ( Mangrove family)
          + Red Mangrove, Rhizophora mangle
     * Rosaceae ( Rose family)
          + Rowans, Whitebeams, Service Trees Sorbus species
          + Hawthorn, Crataegus species
          + Pear, Pyrus species
          + Apple, Malus species
          + Almond, Prunus dulcis
          + Peach, Prunus persica
          + Plum, Prunus domestica
          + Cherry, Prunus species
     * Rubiaceae ( Bedstraw family)
          + Coffee, Coffea species
     * Rutaceae ( Rue family)
          + Citrus, Citrus species
          + Cork-tree, Phellodendron species
          + Euodia, Tetradium species
     * Salicaceae ( Willow family)
          + Aspen, Populus species
          + Poplar, Populus species
          + Willow, Salix species

   Yellow maple in fall.
   Enlarge
   Yellow maple in fall.
     * Sapindaceae (including Aceraceae, Hippocastanaceae) ( Soapberry
       family)
          + Maple, Acer species
          + Buckeye, Horse-chestnut, Aesculus species
          + Mexican Buckeye, Ungnadia speciosa
          + Lychee, Litchi sinensis
          + Golden rain tree, Koelreuteria
     * Sapotaceae ( Sapodilla family)
          + Argan, Argania spinosa
          + Gutta-percha, Palaquium species
          + Tambalacoque, or "dodo tree", Sideroxylon grandiflorum,
            previously Calvaria major
     * Simaroubaceae family
          + Tree of heaven, Ailanthus species
     * Theaceae ( Camellia family)
          + Gordonia, Gordonia species
          + Stuartia, Stuartia species
     * Thymelaeaceae ( Thymelaea family)
          + Ramin, Gonystylus species
     * Ulmaceae ( Elm family)
          + Elm, Ulmus species
          + Zelkova, Zelkova species
     * Verbenaceae family
          + Teak, Tectona species

Monocotyledons (Liliopsida)

   Coconut Palm, a monocotyledonous tree.
   Enlarge
   Coconut Palm, a monocotyledonous tree.
     * Agavaceae ( Agave family)
          + Cabbage tree, Cordyline australis
          + Dragon tree, Dracaena draco
          + Joshua tree, Yucca brevifolia
     * Arecaceae (Palmae) (Palm family)
          + Areca Nut, Areca catechu
          + Coconut Cocos nucifera
          + Date Palm, Phoenix dactylifera
          + Chusan Palm, Trachycarpus fortunei
     * Poaceae ( grass family)
          + Bamboos Poaceae subfamily Bambusoideae
     * Note that banana 'trees' are not actually trees; they are not woody
       nor is the stalk perennial.

Conifers (Pinophyta; softwood trees)

     * Araucariaceae ( Araucaria family)
          + Araucaria, Araucaria species
          + Kauri, Agathis species
          + Wollemia, Wollemia nobilis
     * Cupressaceae (Cypress family)
          + Cypress, Cupressus species
          + Cypress, Chamaecyparis species
          + Juniper, Juniperus species
          + Alerce or Patagonian cypress, Fitzroya cupressoides
          + Sugi, Cryptomeria japonica
          + Coast Redwood, Sequoia sempervirens
          + Giant Sequoia, Sequoiadendron giganteum
          + Dawn Redwood, Metasequoia glyptostroboides
          + Western Redcedar Thuja plicata
          + Bald Cypress, Taxodium species
     * Pinaceae ( Pine family)
          + White pine, Pinus species
          + Pinyon pine, Pinus species
          + Pine, Pinus species
          + Spruce, Picea species
          + Larch, Larix species
          + Douglas-fir, Pseudotsuga species
          + Fir, Abies species
          + Cedar, Cedrus species
     * Podocarpaceae ( Yellowwood family)
          + African Yellowwood, Afrocarpus falcatus
          + Totara, Podocarpus totara
          + Miro, Prumnopitys ferruginea
          + Kahikatea, Dacrycarpus dacrydioides
          + Rimu, Dacrydium cupressinum
     * Sciadopityaceae,
          + Kusamaki, Sciadopitys species
     * Taxaceae ( Yew family)
          + Yew, Taxus species

Ginkgos (Ginkgophyta)

     * Ginkgoaceae ( Ginkgo family)
          + Ginkgo, Ginkgo biloba

Cycads (Cycadophyta)

     * Cycadaceae family
          + Ngathu cycad, Cycas angulata
     * Zamiaceae family
          + Wunu cycad, Lepidozamia hopei

Ferns (Pterophyta)

     * Cyatheaceae and Dicksoniaceae families
          + Tree ferns, Cyathea, Alsophila, Dicksonia (not a monophyletic
            group)

Life stages

   The life cycles of trees, especially conifers, are divided into the
   following stages in forestry for survey and documentation purposes,
   though the boundaries between stages vary among foresters:
    1. Seed
    2. Seedling: the above-ground part of the embryo that sprouts from the
       seed
    3. Sapling: After the seedling reaches 1 m tall, and until it reaches
       7 cm in stem diameter
    4. Pole: young trees from 7–30 cm diameter
    5. Mature tree: over 30 cm diameter, reproductive years begin
    6. Old tree: dominate old growth forest; height growth slows greatly,
       with majority of productivity in seed production
    7. Overmature: dieback and decay become common
    8. Snag: standing dead wood
    9. Log/ debris: fallen dead wood

   Tree diameters are measured at height of between 1.3–1.5 m above the
   highest point on the ground at its base (known as "breast height"). The
   7 cm diameter definition is economically based, from the smallest
   saleable stem size (for paper production, etc), and the 30 cm diameter
   is the smallest base diameter for sawlogs. Each stage may be uniquely
   perceptive to different pathogens and suitable for especially adapted
   arboreal animals.

   Retrieved from " http://en.wikipedia.org/wiki/Tree"
   This reference article is mainly selected from the English Wikipedia
   with only minor checks and changes (see www.wikipedia.org for details
   of authors and sources) and is available under the GNU Free
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