Tree

This is about the original, biological meaning of tree. For other meanings of the word "tree" see tree (graph theory) and tree data structure.

---

A tree is defined as a perennial plant consisting of one or more large woody stems. The component parts of a tree are the roots, trunk(s), branches, twigs and leaves. A small group of trees growing together is called a grove[?] or coppice, and a large population of mixed tree species is called a forest.

Tree stems consist mainly of transport tissues (xylem and phloem). In fact, wood consists of xylem cells, and the bark is primarily made of phloem.

The roots of a tree are generally embedded in earth and absorb water and nutrients from the surrounding soil. Above ground, the trunk gives height to the leaf-bearing branches to aid in their competition with other trees for sunlight. In many tree species, the branches spread so as to present the largest possible leaf surface area to the sun.

A tree may not have all the organs mentioned here: most palms do not have branches, the saguaro of North America has no functional leaves, and tree ferns do not have bark. Based on their rough shape and size, all these are nonetheless considered trees.

Some types of tree can grow to over 100 meters tall and/or live for several millennia if circumstances are optimal. A plant that is similar to trees, but generally having smaller, multiple trunks, is often called a shrub, although boundary between the two categories is not precise.

Several biotopes are defined largely by the trees that inhabit them, for example, the rainforest and the taiga.

Trees often serve as important symbols in mythologies and religions. Examples are Yggdrasil in the Norse Mythology, the Christmas Tree that is derived from Germanic mythology, the Tree of Knowledge of Judaism and Christianity, and the Bodhi tree in Buddhism.

Trees show a wide variety of leaf types and shapes, bark, flowers, fruit, etc. Trees occur in several diverse families of plants. The earliest trees were probably tree ferns, which once grew in vast forests. Later the conifers, ginkgos and cycads appeared (modern cycads no longer appear as trees). Most species of trees today are flowering plants, which were the most recent to appear. The list below gives some examples of well known trees and how they are typically classified.

Table of contents 1 Flowering plants (Magnoliophyta) 2 Conifers 3 Ginkgos 4 Ferns 5 See also

Flowering plants (Magnoliophyta)

• Aceraceae family
  • Norway Maple, Acer platanoides
  • European Sycamore, Acer pseudoplatanus
  • Red Maple[?], Acer rubrum
• Aquifoliaceae[?] family
  • Common Holly, Ilex aquifolium
  • Tarajo Holly, Ilex latifolia
• Betulaceae family
  • Common Alder, Alnus glutinosa
  • Silver Birch, Betula pendula
• Fagaceae family
  • Sweet Chestnut, Castanea sativa
  • American Beech, Fagus grandifolia
  • Oriental Beech, Fagus orientalis
  • Common Beech, Fagus sylvatica
  • Black Beech, Nothofagus solandri
  • English Oak, Quercus robur
• Fouquieriaceae family
  • Boojum, Fouquieria columnaris
• Juglandaceae[?] family
  • Common Walnut, Juglans Regia
  • Black Walnut, Juglans nigra
  • Hickories, Carya species
• Leguminosae family
  • Honey Locust[?] (Gleditsia triacanthos)
  • Pau Brasil, Brazilwood, South American Redwood, Caesalpinia echinata[?]
  • Sappanwood, East Indian Redwood, Caesalpinia sappan[?]
• Meliaceae family (Mahogany family)
  • Neem, Azadirachta indica (A. Juss)
  • Thai Neem, Azadirachta siamensis
  • Marango, Azadirachta excelsa (Jack)
  • Persian Lilac, Melia azedarach
  • Melia toosendan
  • Gurke, Melia volkensii
  • Mahogany, Swietenia mahagoni
• Myristicaceae[?] family
  • Nutmeg, Mysristica fragrans
• Myrtaceae[?] family
  • Silver Gum, Eucalyptus cordata
• Oleaceae family
  • Olive, Olea europaea
• Palmae family, also called Palmaceae or Arecaceae, the palm family
  • Areca Nut, sometimes miscalled "Betel Nut", Areca catechu
  • Coconut Cocos nucifera
  • Canary Island Date Palm, Phoenix canariensis
  • date Palm, Phoenix dactylifera
  • Chusan Palm, Trachycarpus fortunei
• Rhizophoraceae[?], the mangrove family
  • Red Mangrove, Rhizophora mangle
• Rosaceae family
  • Common Hawthorn, Crataegus monogyna
  • apple, Malus domestica
  • Apricot, Prunus armeniaca
  • Almond, Prunus dulcis
  • Fuji Cherry, Prunus incisa
  • Peach, Prunus persica
  • Pear, Pyrus communis
  • Rowan[?], Sorbus aucuparia
• Rubiaceae family
  • coffee, Coffea arabica
  • coffee, Coffea robusta
• Rutaceae family
  • Lime, Citrus aurantiifolia
  • Sour Orange, Citrus aurantium, Citrus bigaradia, Citrus vulgaris
  • Sweet Orange, Citrus sinensis
  • Grapefruit, Citrus paradisi
  • Mandarin, also called Tangerine, Citrus reticulata, Citrus nobilis
  • Lemon, Citrus limon, Citrus limonum
  • Satsuma, Citrus unshiu, Citrus reticulata, Citrus nobilis
• Salicaceae[?] family
  • Aspen, Populus tremula
• Sapotaceae[?] family
  • Tambalacoque, or dodo tree, Sideroxylon grandiflorum, previously Calvaria major
• Sterculiaceae[?] family
  • Cacao, the source of cocoa, Theobroma cacao
• Tiliaceae[?] family. The Lime trees in this family are also known as Linden trees: see Tilia.
  • American Lime, Tilia americana
  • Common Lime, Tilia europaea
  • Mongolian Lime, Tilia mongolica
  • Silver Lime, Tilia tomentosa, Tilia argentea

Conifers

• Cupressaceae[?] family
  • Alerce or Patagonian cypress, Fitzroya cupressoides
  • Eastern redcedar[?], Juniperus virginiana
• Pinaceae[?] family
  • Norway spruce, Picea abies
  • European larch, Larix decidua
  • Stone pine, Pinus pinea
  • Monterey pine, Pinus Radiata
  • White pine[?], Pinus strobus
  • Scots Pine, Pinus sylvestris
  • Douglas-fir, Pseudotsuga menziesii
  • Bigcone Douglas-fir, Pseudotsuga macrocarpa
• Taxodiaceae family
  • Japanese Cedar, Cryptomeria japonica
  • California Coast redwood, Sequoia sempervirens
  • Giant sequoia or Giant redwood, Sequoiadendron giganteum
  • Chinese Dawn redwood[?], Metasequoia glyptostroboides
  • Baldcypress, Taxodium distichum, Taxodium ascendens, Taxodium mucronatum

Ginkgos

• Ginkgoaceae family
  • Ginkgo, Ginkgo biloba

Ferns

• Cyatheaceae[?] and Dicksoniaceae[?] families
  • Tree ferns, Cyathea, Alsophila, Dicksonia

See also

• Trees of the world
  • Trees of Britain and Ireland
  • Trees of Canada
  • Trees of New Zealand
• Fruit trees
• Woodland management
• Bonsai