Array ( [0] => {{Short description|Perennial woody plant with elongated trunk}} [1] => {{Other uses}} [2] => {{Good article}} [3] => {{pp-semi-indef}} [4] => {{pp-move-indef}} [5] => {{EngvarB|date=September 2016}} [6] => {{Use dmy dates|date=January 2024}} [7] => [[File:Ash Tree - geograph.org.uk - 590710.jpg|thumb|Common ash (''[[Fraxinus excelsior]]''), a [[deciduous]] broad-leaved ([[angiosperm]]) tree]] [8] => [[File:Larix decidua Aletschwald.jpg|thumb|European larch (''[[Larix decidua]]''), a [[conifer]]ous tree which is also deciduous]] [9] => In [[botany]], a '''tree''' is a [[perennial plant]] with an elongated [[Plant stem|stem]], or [[trunk (botany)|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 [[Arecaceae|palms]], [[Cyatheales|tree ferns]], [[Musa (genus)|bananas]], and [[bamboo]]s are also trees. [10] => [11] => Trees are not a [[Monophyletic group|monophyletic taxonomic group]] but consist of a wide variety of plant species that [[Convergent evolution|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 [[angiosperm]]s or hardwoods; of the rest, many are [[gymnosperm]]s 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 around three trillion mature trees in the world. [12] => [13] => A tree typically has many secondary branches supported clear of the ground by the trunk, which 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 (botany)|bark]] which serves as a protective barrier. Below the ground, the [[#Roots|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. [14] => [15] => 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 [[spore]]s instead. [16] => [17] => Trees play a significant role in reducing [[Soil erosion|erosion]] and moderating the [[climate]]. They remove [[carbon dioxide]] from the [[Atmosphere of Earth|atmosphere]] and store large quantities of [[carbon]] in their tissues. Trees and [[forest]]s provide a habitat for many species of animals and plants. [[Tropical rainforest]]s are among the most [[Biodiversity|biodiverse]] habitats in the world. Trees provide [[shade tree|shade and shelter]], timber for construction, fuel for cooking and heating, and fruit for food as well as having many other uses. In much 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 grove]]s in various cultures, and they play a role in many of the world's [[mythology|mythologies]]. [18] => [19] => ==Definition== [20] => [[File:Tree secondary growth diagram.svg|thumb|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.]] [21] => [22] => Although "tree" is a term of common parlance, there is no universally recognised precise definition of what a tree is, either [[botany|botanically]] or in common language.{{Cite journal |last1=Ehrenberg |first1=Rachel |title=What makes a tree a tree? |url=https://knowablemagazine.org/article/living-world/2018/what-makes-tree-tree |journal=Knowable Magazine |doi=10.1146/knowable-033018-032602 |date=30 March 2018 |doi-access=free |access-date=21 June 2021 |archive-date=28 June 2021 |archive-url=https://web.archive.org/web/20210628151407/https://knowablemagazine.org/article/living-world/2018/what-makes-tree-tree |url-status=live }}{{cite web |url=http://www.as.miami.edu/qr/arboretum/what_is_a_tree.html |title=What is a tree? |year=2012 |work=Smartphone tour |publisher=University of Miami: John C. Gifford Arboretum |access-date=23 September 2014 |archive-url=https://web.archive.org/web/20140420004648/http://www.as.miami.edu/qr/arboretum/what_is_a_tree.html |archive-date=20 April 2014 |url-status=dead }} In its broadest sense, a tree is any plant with the general form of an elongated stem, or trunk, which supports the [[photosynthesis|photosynthetic]] leaves or branches at some distance above the ground.{{cite web |url=http://www.newton.dep.anl.gov/askasci/bot00/bot00761.htm |archive-url=https://web.archive.org/web/20131206131101/http://www.newton.dep.anl.gov/askasci/bot00/bot00761.htm |archive-date=6 December 2013 |title=Tree definition |last=Tokuhisa |first=Jim |publisher=Newton Ask a Scientist |access-date=18 December 2021 |url-status=dead }} Trees are also typically defined by height,{{cite journal | last=Gschwantner |first=Thomas |display-authors=etal | year=2009 | title=Common tree definitions for national forest inventories in Europe | journal=Silva Fennica | volume=43 | issue=2 | pages=303–321 | doi=10.14214/sf.463| doi-access=free }} with smaller plants from {{convert|0.5|to|10|m|ft|abbr=on}} being called [[shrub]]s,{{cite web |url=http://www.treedictionary.com/ |title=Tree Biology Dictionary |last=Keslick |first=John A. |year=2004 |access-date=30 July 2012 |archive-date=19 March 2021 |archive-url=https://web.archive.org/web/20210319140326/http://www.treedictionary.com/ |url-status=live }} so the minimum height of a tree is only loosely defined. Large [[herbaceous]] plants such as [[papaya]] and bananas are trees in this broad sense.{{cite web |url=http://people.umass.edu/psoil370/Syllabus-files/Agroforestry_Principles.pdf |title=Agroforestry principles |last1=Martin |first1=Franklin |last2=Sherman |first2=Scott |year=2007 |work=Echo technical notes |access-date=22 September 2014 |archive-date=28 July 2013 |archive-url=https://web.archive.org/web/20130728035517/http://people.umass.edu/psoil370/Syllabus-files/Agroforestry_Principles.pdf |url-status=live }} [23] => [24] => A commonly applied narrower definition is that a tree has a woody trunk formed by [[secondary growth]], meaning that the trunk thickens each year by growing outwards, in addition to the primary upwards growth from the [[apical meristem|growing tip]].{{cite web |url=http://warnell.forestry.uga.edu/SERVICE/LIBRARY/index.php3?docID=171 |title=Secondary Growth Anatomy and Tree Rings |last=Coder |first=Kim D. |publisher=Warnell School of Forest Resources, University of Georgia |date=August 1999 |access-date=23 September 2014 |url-status=dead |archive-url=https://web.archive.org/web/20140908112429/http://warnell.forestry.uga.edu/SERVICE/LIBRARY/index.php3?docID=171 |archive-date=8 September 2014 }} Under such a definition, herbaceous plants such as [[Arecaceae|palms]], bananas and papayas are not considered trees regardless of their height, growth form or stem girth. Certain [[Monocotyledon|monocots]] may be considered trees under a slightly looser definition;{{cite journal | last=Gyde |first=Lund H. | year=1999 | title=A forest by any other name … | journal=Environmental Science & Policy | volume=2 | issue=2| pages=125–133 | doi=10.1016/s1462-9011(98)00046-x}} while the [[Yucca brevifolia|Joshua tree]], bamboos and palms do not have secondary growth and never produce true wood with growth rings,{{cite web |url=http://www.botany.wisc.edu/courses/botany_400/Lecture/0pdf/25MonocotOrigin.pdf |title=Diversity and evolution of monocots |publisher=University of Wisconsin |access-date=22 September 2014 |archive-date=22 October 2016 |archive-url=https://web.archive.org/web/20161022091304/http://www.botany.wisc.edu/courses/botany_400/Lecture/0pdf/25MonocotOrigin.pdf |url-status=live }}{{cite book |first1=Tony |last1=Rodd |first2=Jennifer |last2=Stackhouse |title=Trees: A Visual Guide |url=https://books.google.com/books?id=Mpsc2hsYk1YC&pg=PA112 |year=2008 |publisher=University of California Press |isbn=978-0-520-25650-7 |page=112 |access-date=28 February 2016 |archive-date=4 March 2017 |archive-url=https://web.archive.org/web/20170304154820/https://books.google.com/books?id=Mpsc2hsYk1YC&pg=PA112 |url-status=live }} they may produce "pseudo-wood" by [[lignin|lignifying]] cells formed by primary growth.{{cite web |url=http://www.bio.miami.edu/dana/dox/stem.html |title=Monocot stems |work=The stem |publisher=University of Miami |access-date=22 September 2014 |archive-date=19 March 2021 |archive-url=https://web.archive.org/web/20210319140404/http://www.bio.miami.edu/dana/dox/stem.html |url-status=live }} Tree species in the genus [[Dracaena (plant)|''Dracaena'']], despite also being monocots, do have secondary growth caused by meristem in their trunk, but it is different from the thickening meristem found in dicotyledonous trees.{{cite journal |last=Jura-Morawiec |first=Joanna |title=Formation of amphivasal vascular bundles in ''Dracaena draco'' stem in relation to rate of cambial activity |journal=Trees |volume=29 |issue=5 |year=2015 |pages=1493–1499 |issn=0931-1890 |doi=10.1007/s00468-015-1230-3|bibcode=2015Trees..29.1493J |doi-access=free }} [25] => [26] => Aside from structural definitions, trees are commonly defined by use; for instance, as those plants which yield lumber.{{cite web |url=http://www.fao.org/docrep/006/t7540e/T7540E04.htm |title=Community forestry rapid appraisal of tree and land tenure |publisher=Food and Agriculture Organisation |access-date=1 October 2014 |archive-date=17 July 2018 |archive-url=https://web.archive.org/web/20180717100135/http://www.fao.org/docrep/006/t7540e/T7540E04.htm |url-status=live }} [27] => [28] => ==Overview== [29] => {{redirect|Saplings|the novel|Saplings (novel)|the film|The Saplings|the episode|Saplings (Weeds)}} [30] => The tree growth habit is an [[evolution]]ary [[adaptation]] found in different groups of plants: by growing taller, trees are able to compete better for sunlight.{{cite book |last1=Lowman |first1=V. |last2=Rinker |first2=H. Bruce |title=Forest Canopies |url=https://books.google.com/books?id=T9qY2AxnUowC&pg=PA119 |year=2004 |publisher=Academic Press |isbn=978-0-08-049134-9 |page=119 |access-date=28 February 2016 |archive-date=4 March 2017 |archive-url=https://web.archive.org/web/20170304124617/https://books.google.com/books?id=T9qY2AxnUowC&pg=PA119 |url-status=live }} Trees tend to be tall and long-lived,{{cite journal |last1=Petit |first1=Rémy J. |last2=Hampe |first2=Arndt |year=2006 |title=Some Evolutionary Consequences of Being a Tree |url=http://www.ecologicalevolution.org/content/Petit_How2BeATree.pdf |url-status=dead |journal=Annual Review of Ecology, Evolution, and Systematics |volume=37 |pages=187–214 |doi=10.1146/annurev.ecolsys.37.091305.110215 |archive-url=https://web.archive.org/web/20140116084547/http://www.ecologicalevolution.org/content/Petit_How2BeATree.pdf |archive-date=16 January 2014 |hdl=10261/64097}} some reaching several thousand years old.{{cite journal |url=http://www.planta.cn/forum/files_planta/the_limits_to_tree_height_995.pdf |archive-url=https://web.archive.org/web/20121021080125/http://www.planta.cn/forum/files_planta/the_limits_to_tree_height_995.pdf |archive-date=21 October 2012 |title=The limits to tree height |last1=Koch |first1=George W. |author2=Sillett, Stephen C. |author3=Jennings, Gregory M. |author4=Davis, Stephen D. |year=2004 |journal=Letters to Nature |volume=428 |issue=6985 |pages=851–4 |publisher=Nature Publishing Group |doi=10.1038/nature02417 |pmid=15103376 |bibcode=2004Natur.428..851K |s2cid=11846291 |access-date=18 December 2021 |url-status=dead }} Several trees are among the oldest organisms now living.{{cite magazine|title=These are 11 of the Oldest Things in the World|url=http://time.com/10688/worlds-oldest-things/|magazine=Time|access-date=11 October 2017|archive-date=17 October 2017|archive-url=https://web.archive.org/web/20171017052036/http://time.com/10688/worlds-oldest-things/|url-status=live}} Trees have modified structures such as thicker stems composed of specialised cells that add structural strength and durability, allowing them to grow taller than many other plants and to spread out their foliage. They differ from [[shrub]]s, which have a similar growth form, by usually growing larger and having a single main stem; but there is no consistent distinction between a tree and a shrub,{{cite book |last1=Hawthorne |first1=William |author2=Lawrence, Anna |title=Plant Identification: Creating User-Friendly Field Guides for Biodiversity Management |url=https://books.google.com/books?id=rHEpVBM5-eIC&pg=PA138 |year=2012 |publisher=Routledge |isbn=978-1-84407-079-4 |page=138 |access-date=28 February 2016 |archive-date=7 February 2017 |archive-url=https://web.archive.org/web/20170207094210/https://books.google.com/books?id=rHEpVBM5-eIC&pg=PA138 |url-status=live }} made more confusing by the fact that trees may be reduced in size under harsher environmental conditions such as on mountains and [[subarctic]] areas. The tree form has evolved separately in unrelated classes of plants in response to similar environmental challenges, making it a classic example of [[parallel evolution]]. With an estimated 60,000-100,000 species, the number of trees worldwide might total twenty-five per cent of all living plant species.{{cite news |url=http://usatoday30.usatoday.com/tech/science/2008-05-02-890171068_x.htm |title=Scientists to capture DNA of trees worldwide for database |last=Hajela |first=Deepti |access-date=18 December 2021 |work=USA Today |date=2 May 2008 |archive-date=19 March 2022 |archive-url=https://web.archive.org/web/20220319090451/http://usatoday30.usatoday.com/tech/science/2008-05-02-890171068_x.htm |url-status=live }}{{cite news |url=https://www.bbc.com/news/science-environment-39492977 |title=World is home to '60,000 tree species' |last=Kinver |first=Mark |access-date=18 December 2021 |work=BBC Science and Environment News |date=5 April 2017 |archive-date=18 December 2021 |archive-url=https://web.archive.org/web/20211218151721/https://www.bbc.com/news/science-environment-39492977 |url-status=live }} The greatest number of these grow in tropical regions; many of these areas have not yet been fully surveyed by [[botanist]]s, making tree diversity and ranges poorly known.{{cite book |title=Plant diversity and complexity patterns: local, regional, and global dimensions: proceedings of an international symposium held at the Royal Danish Academy of Sciences and Letters in Copenhagen, Denmark, 25–28 May 2003 |last1=Friis |first1=Ib |last2=Balslev |first2=Henrik |last3=Kongelige |first3=Danske |editor-first4=Videnskabernes |editor-last4=Selskab (eds.) |year=2005 |publisher=Kgl. Danske Videnskabernes Selskab |isbn=978-87-7304-304-2 |pages=57–59}} [31] => [32] => [[File:Nedravazhakola.jpg|thumb|left|Tall [[herbaceous]] [[monocotyledon]]ous plants such as banana lack secondary growth, but are trees under the broadest definition.]] [33] => [34] => The majority of tree species are [[angiosperm]]s or hardwoods. Of the rest, many are [[gymnosperm]]s or softwood trees;{{cite web |title=The Gymnosperms (Conifers, cycads and allies) |url=http://www.theplantlist.org/browse/G/ |website=The Plant List |access-date=14 November 2017 |date=2010 |archive-date=24 August 2013 |archive-url=https://web.archive.org/web/20130824024109/http://www.theplantlist.org/browse/G/ |url-status=live }} these include [[conifer]]s, [[cycad]]s, [[Ginkgoales|ginkgophytes]] and [[Gnetophyta|gnetales]], which produce seeds which are not enclosed in fruits, but in open structures such as pine [[conifer cone|cones]], and many have tough waxy leaves, such as pine needles.{{cite book | title=The Gymnosperms |last1=Biswas |first1=Chhaya |author2=Johri, B.M. | publisher=Springer | date=1997 | isbn=978-3-662-13166-4}} Most angiosperm trees are [[eudicots]], the "true dicotyledons", so named because the seeds contain two [[cotyledon]]s or seed leaves. There are also some trees among the old lineages of flowering plants called [[Basal angiosperms|basal angiosperms or paleodicots]]; these include ''[[Amborella]]'', ''[[Magnolia]]'', [[Myristica|nutmeg]] and [[avocado]],{{cite book | url=https://books.google.com/books?id=_xl8MCXURoYC&pg=PA10 | title=Functional Biology of Plants | last1=Hodson | first1=Martin J. | author2=Bryant, John A. | publisher=John Wiley | date=2012 | pages=9–11 | isbn=978-1-119-96887-0 | access-date=28 February 2016 | archive-date=2 September 2021 | archive-url=https://web.archive.org/web/20210902214405/https://books.google.com/books?id=_xl8MCXURoYC&pg=PA10 | url-status=live }} while trees such as bamboo, palms and bananas are [[monocots]]. [35] => [36] => Wood gives structural strength to the trunk of most types of tree; this supports the plant as it grows larger. The vascular system of trees allows water, nutrients and other chemicals to be distributed around the plant, and without it trees would not be able to grow as large as they do. Trees, as relatively tall plants, need to draw water up the stem through the xylem from the roots by the suction produced as water evaporates from the leaves. If insufficient water is available the leaves will die.{{cite web |url=http://cronodon.com/BioTech/Plant_Transport.html |title=Transport in plants |date=28 January 2007 |work=BioTech |publisher=Cronodon Museum |access-date=21 July 2012 |archive-date=14 October 2012 |archive-url=https://web.archive.org/web/20121014094306/http://cronodon.com/BioTech/Plant_Transport.html |url-status=live }} The three main parts of trees include the root, stem, and leaves; they are integral parts of the vascular system which interconnects all the living cells. In trees and other plants that develop wood, the [[vascular cambium]] allows the expansion of vascular tissue that produces woody growth. Because this growth ruptures the epidermis of the stem, woody plants also have a [[cork cambium]] that develops among the phloem. The cork cambium gives rise to thickened cork cells to protect the surface of the plant and reduce water loss. Both the production of wood and the production of cork are forms of secondary growth.{{cite web |url=http://warnell.forestry.uga.edu/SERVICE/LIBRARY/index.php3?docID=171 |archive-url=https://web.archive.org/web/20140908112429/http://warnell.forestry.uga.edu/SERVICE/LIBRARY/index.php3?docID=171 |archive-date=8 September 2014 |title=Secondary Growth Anatomy and Tree Rings |last=Coder |first=Kim D. |publisher=Warnell School of Forest Resources, University of Georgia |date=1 August 1999 |access-date=8 September 2014 |url-status=dead }} [37] => [38] => Trees are either [[evergreen]], having foliage that persists and remains green throughout the year,{{cite web |url=http://www.thefreedictionary.com/evergreen |title=Evergreen |work=TheFreeDictionary |access-date=7 August 2012 |archive-date=20 July 2012 |archive-url=https://web.archive.org/web/20120720092159/http://www.thefreedictionary.com/evergreen |url-status=live }} or [[deciduous]], shedding their leaves at the end of the growing season and then having a dormant period without foliage.{{cite web |url=http://www.thefreedictionary.com/deciduous |title=Deciduous |work=TheFreeDictionary |access-date=7 August 2012 |archive-date=21 July 2012 |archive-url=https://web.archive.org/web/20120721153143/http://www.thefreedictionary.com/deciduous |url-status=live }} Most conifers are evergreens, but larches (''[[Larix]]'' and ''[[Pseudolarix]]'') are deciduous, dropping their needles each autumn, and some species of cypress (''[[Glyptostrobus]]'', ''[[Metasequoia]]'' and ''[[Taxodium]]'') shed small leafy shoots annually in a process known as [[cladoptosis]]. The [[Crown (botany)|crown]] is the spreading top of a tree including the branches and leaves,{{cite web |url=http://www.thefreedictionary.com/crown |title=Crown |work=TheFreeDictionary |access-date=7 August 2012 |archive-date=14 July 2012 |archive-url=https://web.archive.org/web/20120714195628/http://www.thefreedictionary.com/crown |url-status=live }} while the uppermost layer in a forest, formed by the crowns of the trees, is known as the [[Canopy (biology)|canopy]].{{cite web |url=http://www.thefreedictionary.com/canopy |title=Canopy |work=TheFreeDictionary |access-date=7 August 2012 |archive-date=12 July 2012 |archive-url=https://web.archive.org/web/20120712030046/http://www.thefreedictionary.com/canopy |url-status=live }} A sapling is a young tree.{{cite web |url=http://www.thefreedictionary.com/sapling |title=Sapling |work=TheFreeDictionary |access-date=7 August 2012 |archive-date=7 April 2014 |archive-url=https://web.archive.org/web/20140407194013/http://www.thefreedictionary.com/sapling |url-status=live }} [39] => [40] => Many tall palms are herbaceous{{cite web |url=https://www.smmflowers.org/bloom/ANF-other/Glossary_UCLA_SantaMonicas_Web.htm |title=Detailed Scientific Descriptions, from A Naturalist's Flora of the Santa Monica Mountains and Simi Hills, California |publisher=National Park Service |access-date=6 May 2022 |quote=herbaceous monocotyledons lack cambial secondary growth but may have tough leaves and hard, fibrous stems (e.g., palms and Hesperoyucca whipplei) |archive-date=6 November 2022 |archive-url=https://web.archive.org/web/20221106131618/https://www.smmflowers.org/bloom/ANF-other/Glossary_UCLA_SantaMonicas_Web.htm |url-status=live }} monocots, which do not undergo secondary growth and never produce wood. In many tall palms, the terminal bud on the main stem is the only one to develop, so they have unbranched trunks with large spirally arranged leaves. Some of the tree ferns, [[Order (biology)|order]] [[Cyatheales]], have tall straight trunks, growing up to {{convert|20|m}}, but these are composed not of wood but of [[rhizome]]s which grow vertically and are covered by numerous [[Adventitiousness|adventitious roots]].{{cite encyclopedia |url=http://www.britannica.com/EBchecked/topic/603988/tree-fern |title=Tree fern |last=Yatskievych |first=George |encyclopedia=Encyclopædia Britannica |access-date=4 August 2012 |archive-date=10 June 2012 |archive-url=https://web.archive.org/web/20120610051907/http://www.britannica.com/EBchecked/topic/603988/tree-fern |url-status=live }} [41] => [42] => ==Distribution== [43] => {{further |Forest}} [44] => [[File:Daintree Rainforest 4.jpg|thumb|upright|left|The [[Daintree Rainforest]]]] [45] => [46] => The number of trees in the world, according to a 2015 estimate, is 3.04 trillion, of which 1.39 trillion (46%) are in the tropics or [[Subtropics|sub-tropics]], 0.61 trillion (20%) in the [[Temperate climate|temperate zones]], and 0.74 trillion (24%) in the [[Forest|coniferous]] [[Taiga|boreal forests]]. The estimate is about eight times higher than previous estimates, and is based on tree densities measured on over 400,000 plots. It remains subject to a wide margin of error, not least because the samples are mainly from Europe and North America. The estimate suggests that about 15 billion trees are cut down annually and about 5 billion are planted. In the 12,000 years since the start of human agriculture, the number of trees worldwide has decreased by 46%.{{Cite journal |title=Mapping tree density at a global scale |journal=Nature |date=2 September 2015 |issn=1476-4687 |volume=advance online publication |issue=7568 |pages=201–205 |doi=10.1038/nature14967 |pmid=26331545 |first1=T. W. |last1=Crowther |first2=H. B. |last2=Glick |first3=K. R. |last3=Covey |first4=C. |last4=Bettigole |first5=D. S. |last5=Maynard |first6=S. M. |last6=Thomas |first7=J. R. |last7=Smith |first8=G. |last8=Hintler |first9=M. C. |last9=Duguid |bibcode=2015Natur.525..201C |s2cid=4464317 |url=https://resolver.sub.uni-goettingen.de/purl?gro-2/35970 |access-date=29 November 2023 |archive-date=1 January 2024 |archive-url=https://web.archive.org/web/20240101151145/https://publications.goettingen-research-online.de/handle/2/35970 |url-status=live }}{{cite web |url=https://www.npr.org/sections/goatsandsoda/2015/09/02/436919052/tree-counter-is-astonished-by-how-many-trees-there-are |title=Tree Counter Is Astonished By How Many Trees There Are |publisher=National Public Radio |date=2 September 2015 |first=Nell |last=Greenfieldboyce |author-link=Nell Greenfieldboyce |access-date=4 April 2018 |archive-date=8 March 2018 |archive-url=https://web.archive.org/web/20180308193905/https://www.npr.org/sections/goatsandsoda/2015/09/02/436919052/tree-counter-is-astonished-by-how-many-trees-there-are |url-status=live }}{{Cite news |last1=Amos |first1=Jonathan |title=Earth's trees number 'three trillion' |journal=BBC News |url=https://www.bbc.co.uk/news/science-environment-34134366 |access-date=3 September 2015 |date=3 September 2015 |archive-date=19 July 2019 |archive-url=https://web.archive.org/web/20190719204607/https://www.bbc.co.uk/news/science-environment-34134366 |url-status=live }}{{Cite journal |title=Global count reaches 3 trillion trees |journal=Nature |url=http://www.nature.com/news/global-count-reaches-3-trillion-trees-1.18287 |access-date=3 September 2015 |doi=10.1038/nature.2015.18287 |year=2015 |last1=Ehrenberg |first1=Rachel |s2cid=189415504 |archive-date=21 December 2019 |archive-url=https://web.archive.org/web/20191221053821/http://www.nature.com/news/global-count-reaches-3-trillion-trees-1.18287 |url-status=live }} There are approximately 64,100 known tree species in the world. With 43% of all tree species, South America has the highest biodiversity, followed by Eurasia (22%), Africa (16%), North America (15%), and Oceania (11%).{{Cite web |last=Pappas |first=Stephanie |title=Thousands of Tree Species Remain Unknown to Science |url=https://www.scientificamerican.com/article/thousands-of-tree-species-remain-unknown-to-science/ |access-date=18 January 2023 |website=[[Scientific American]] |date=May 2022 |archive-date=17 January 2023 |archive-url=https://web.archive.org/web/20230117172407/https://www.scientificamerican.com/article/thousands-of-tree-species-remain-unknown-to-science/ |url-status=live }} [47] => [48] => In suitable environments, such as the [[Daintree Rainforest]] in [[Queensland]], or the mixed [[Podocarpus|podocarp]] and [[Temperate broadleaf and mixed forest|broadleaf forest]] of [[Ulva Island, New Zealand]], forest is the more-or-less stable [[climax community|climatic climax community]] at the end of a plant succession, where open areas such as grassland are colonised by taller plants, which in turn give way to trees that eventually form a forest canopy.{{cite web |title=Climax Community |url=http://www.eoearth.org/view/article/171226/ |archive-url=https://web.archive.org/web/20140906133528/http://www.eoearth.org/view/article/171226/ |archive-date=6 September 2014 |publisher=Encyclopedia of Earth |access-date=28 June 2014 |url-status=dead }}{{cite web |title=Physical Environments Biosphere Vegetation Succession Moorlands |publisher=Macaulay Institute |url=http://www.macaulay.ac.uk/soilquality/Moorland%20Succession.pdf |access-date=28 June 2014 |archive-date=6 September 2014 |archive-url=https://web.archive.org/web/20140906154403/http://www.macaulay.ac.uk/soilquality/Moorland%20Succession.pdf |url-status=live }} [49] => [50] => [[File:New snow, Swabian Alps (2019).jpg|thumb|Conifers in the [[Swabian Jura|Swabian alps]]]] [51] => [52] => In [[temperateness|cool temperate]] regions, conifers often predominate; a widely distributed climax community in the far north of the northern hemisphere is moist [[taiga]] or northern coniferous forest (also called boreal forest).{{cite web |last=Nelson |first=Rob |title=The Taiga |url=http://www.thewildclassroom.com/biomes/taiga.html |access-date=28 June 2014 |archive-date=6 May 2017 |archive-url=https://web.archive.org/web/20170506045042/http://www.thewildclassroom.com/biomes/taiga.html |url-status=dead }}{{cite web |url=http://dendro.cnre.vt.edu/forsite/ncfbiome.htm |title=Northern Coniferous Forest Biome |access-date=28 June 2014 |work=The Forest Community |publisher=FORSite |quote=The diversity of tree species in the boreal forest is quite low, with black spruce (''Picea mariana''), larch or tamarack (''Larix laricina''), and white spruce (''P. glauca'') the most common species. The former two species generally occupy wet sites with poorly drained mineral or organic soils, while white spruce is the climatic climax species on sites that are drier and higher in nutrient content. Balsam fir (''Abies balsamea'') is a dominant tree species in the eastern half of the biome. |archive-date=30 October 2014 |archive-url=https://web.archive.org/web/20141030070027/http://dendro.cnre.vt.edu/forsite/ncfbiome.htm |url-status=live }} Taiga is the world's largest land [[biome]], forming 29% of the world's forest cover.{{cite web |url=http://www.wilds.mb.ca/taiga/tbsfaq.html |title=Taiga Biological Station: FAQ |publisher=Taiga Biological Station |date=23 March 2010 |access-date=21 February 2011 |archive-date=13 December 2018 |archive-url=https://web.archive.org/web/20181213075347/http://www.wilds.mb.ca/taiga/tbsfaq.html |url-status=live }} The long cold winter of the far north is unsuitable for plant growth and trees must grow rapidly in the short summer season when the temperature rises and the days are long. Light is very limited under their dense cover and there may be little plant life on the forest floor, although fungi may abound.{{cite web |url=http://www.ucmp.berkeley.edu/exhibits/biomes/forests.php/#boreal |title=The forest biome: Boreal forest |publisher=University of California Museum of Paleontology |access-date=28 July 2012 |archive-date=9 August 2012 |archive-url=https://web.archive.org/web/20120809060726/http://www.ucmp.berkeley.edu/exhibits/biomes/forests.php#boreal |url-status=live }} Similar woodland is found on mountains where the altitude causes the average temperature to be lower thus reducing the length of the growing season.{{cite web |url=https://plantecology.unibas.ch/treeline_elevation/index.shtml |title=High elevation treeline research |last=Körner |first=Christian |publisher=University of Basel: Institute of Botany |access-date=28 July 2012 |archive-date=23 October 2016 |archive-url=https://web.archive.org/web/20161023055635/https://plantecology.unibas.ch/treeline_elevation/index.shtml |url-status=live }} [53] => [54] => Where rainfall is relatively evenly spread across the seasons in temperate regions, [[temperate broadleaf and mixed forest]] typified by species like oak, beech, birch and maple is found.{{cite web |url=http://wwf.panda.org/about_our_earth/ecoregions/about/habitat_types/selecting_terrestrial_ecoregions/habitat04.cfm |title=Temperate Broadleaf and Mixed Forest Ecoregions |publisher=WWF |access-date=10 September 2014 |url-status=dead |archive-url=https://web.archive.org/web/20141006121415/http://wwf.panda.org/about_our_earth/ecoregions/about/habitat_types/selecting_terrestrial_ecoregions/habitat04.cfm |archive-date=6 October 2014}} Temperate forest is also found in the southern hemisphere, as for example in the Eastern Australia temperate forest, characterised by ''[[Eucalyptus]]'' forest and open acacia woodland.{{cite web |url=http://wwf.panda.org/about_our_earth/ecoregions/easternaustralia_temperate_forests.cfm |title=Eastern Australia Temperate Forest |publisher=WWF |access-date=10 September 2014 |url-status=dead |archive-url=https://web.archive.org/web/20140910215824/http://wwf.panda.org/about_our_earth/ecoregions/easternaustralia_temperate_forests.cfm |archive-date=10 September 2014}} [55] => [56] => In tropical regions with a [[monsoon climate|monsoon]] or monsoon-like climate, where a drier part of the year alternates with a wet period as in the [[Amazon rainforest]], different species of broad-leaved trees dominate the forest, some of them being deciduous.{{cite web |url=http://www.marietta.edu/~biol/biomes/troprain.htm |title=The tropical rain forest |work=Biomes of the World |publisher=Marietta College |access-date=28 July 2012 |archive-date=23 May 2011 |archive-url=https://web.archive.org/web/20110523222037/http://www.marietta.edu/~biol/biomes/troprain.htm |url-status=live }} In tropical regions with a drier [[savanna climate]] and insufficient rainfall to support dense forests, the canopy is not closed, and plenty of sunshine reaches the ground which is covered with grass and scrub. ''[[Acacia]]'' and [[baobab]] are well adapted to living in such areas.{{cite encyclopedia |url=http://www.britannica.com/EBchecked/topic/242157/grass-savanna |title=Grass savanna |encyclopedia=Encyclopædia Britannica |access-date=28 July 2012 |archive-date=20 November 2012 |archive-url=https://web.archive.org/web/20121120171336/http://www.britannica.com/EBchecked/topic/242157/grass-savanna |url-status=live }} [57] => [58] => ==Parts and function== [59] => [60] => ===Roots=== [61] => [[File:WisconsinScenery.jpg|thumb|A young [[red pine]] (''Pinus resinosa'') with spread of roots visible, as a result of soil erosion]] [62] => {{main|Root}} [63] => [64] => The roots of a tree serve to anchor it to the ground and gather water and nutrients to transfer to all parts of the tree. They are also used for reproduction, defence, survival, energy storage and many other purposes. The [[radicle]] or embryonic root is the first part of a [[seedling]] to emerge from the seed during the process of [[germination]]. This develops into a [[taproot]] which goes straight downwards. Within a few weeks [[lateral root]]s branch out of the side of this and grow horizontally through the upper layers of the soil. In most trees, the taproot eventually withers away and the wide-spreading laterals remain. Near the tip of the finer roots are single cell [[root hair]]s. These are in immediate contact with the soil particles and can absorb water and nutrients such as [[potassium]] in solution. The roots require oxygen to [[Respiration (physiology)|respire]] and only a few species such as [[mangrove]]s and the [[Taxodium ascendens|pond cypress]] (''Taxodium ascendens'') can live in permanently waterlogged soil.{{cite book |title=The World Encyclopedia of Trees |last=Russell |first=Tony |author2=Cutler, Catherine |year=2003 |publisher=Lorenz Books |isbn=978-0-7548-1292-0 |pages=[https://archive.org/details/isbn_9780754812920/page/14 14–15] |url=https://archive.org/details/isbn_9780754812920/page/14}} [65] => [66] => In the soil, the roots encounter the [[hyphae]] of fungi. Many of these are known as [[mycorrhiza]] and form a [[Mutualism (biology)|mutualistic]] relationship with the tree roots. Some are specific to a single tree species, which will not flourish in the absence of its mycorrhizal associate. Others are generalists and associate with many species. The tree acquires minerals such as [[phosphorus]] from the fungus, while the fungus obtains the [[carbohydrate]] products of photosynthesis from the tree.{{cite web |url=http://www.waldwissen.net/wald/baeume_waldpflanzen/oekologie/wsl_mykorrhiza_lebensgemeinschaft/index_EN |title=Mycorrhiza – a fascinating symbiosis in the forest |last1=Egli |first1=S. |author2=Brunner, I. |year=2011 |work=Forestknowledge |publisher=Swiss Federal Research Institute |access-date=15 July 2012 |archive-url=https://web.archive.org/web/20130509045021/https://www.waldwissen.net/wald/baeume_waldpflanzen/oekologie/wsl_mykorrhiza_lebensgemeinschaft/index_EN |archive-date=9 May 2013}} The hyphae of the fungus can link different trees and a network is formed, transferring nutrients and signals from one place to another.{{Cite journal |last=Heijden |first=Marcel G. A. van der |date=15 April 2016 |title=Underground networking |journal=Science |volume=352 |issue=6283 |pages=290–291 |doi=10.1126/science.aaf4694 |pmid=27081054|bibcode=2016Sci...352..290H |s2cid=133399719 }} The fungus promotes growth of the roots and helps protect the trees against predators and pathogens. It can also limit damage done to a tree by pollution as the fungus accumulate [[Heavy metal (chemistry)|heavy metals]] within its tissues.{{cite web |url=https://treesforlife.org.uk/into-the-forest/habitats-and-ecology/ecology/mycorrhizas/ |title=Mycorrhizas |last=Puplett |first=Dan |work=Trees for Life |access-date=15 July 2012 |archive-date=2 November 2019 |archive-url=https://web.archive.org/web/20191102063436/http://treesforlife.org.uk/into-the-forest/habitats-and-ecology/ecology/mycorrhizas/ |url-status=live }} Fossil evidence shows that roots have been associated with mycorrhizal fungi since the early [[Paleozoic]], four hundred million years ago, when the first [[vascular plant]]s colonised dry land.{{cite journal |last=Brundrett |first=Mark C. |year=2002 |title=Coevolution of roots and mycorrhizas of land plants |journal=New Phytologist |volume=154 |issue=2 |pages=275–304 |doi=10.1046/j.1469-8137.2002.00397.x|pmid=33873429 |doi-access=free }} [67] => [68] => [[File:Bombax LalBagh.JPG|thumb|left|Buttress roots of the kapok tree (''[[Ceiba pentandra]]'')]] [69] => Some trees such as [[Alder]] (''Alnus'' species) have a [[Symbiosis|symbiotic]] relationship with ''[[Frankia]]'' species, a filamentous bacterium that can fix nitrogen from the air, converting it into [[ammonia]]. They have [[Actinorhizal plant|actinorhizal]] root nodules on their roots in which the bacteria live. This process enables the tree to live in low nitrogen habitats where they would otherwise be unable to thrive.{{cite web |url=http://web.uconn.edu/mcbstaff/benson/Frankia/FrankiaHome.htm |title=Frankia and Actinorhizal Plants |last=Benson |first=David |publisher=University of Connecticut |access-date=15 July 2012 |archive-date=6 August 2018 |archive-url=https://web.archive.org/web/20180806064343/http://web.uconn.edu/mcbstaff/benson/Frankia/FrankiaHome.htm |url-status=dead }} The plant hormones called [[cytokinin]]s initiate root nodule formation, in a process closely related to mycorrhizal association.{{cite book |title=Signaling in Plants |last=Baluška |first=František |author2=Mancuso, Stefano |year=2009 |publisher=Springer |isbn=978-3-540-89227-4 |pages=83–84 |url=https://books.google.com/books?id=RTFMl0cArgAC&pg=PA83 |access-date=29 May 2020 |archive-date=19 August 2020 |archive-url=https://web.archive.org/web/20200819211216/https://books.google.com/books?id=RTFMl0cArgAC&pg=PA83 |url-status=live }} [70] => [71] => It has been demonstrated that some trees are interconnected through their root system, forming a colony. The interconnections are made by the [[inosculation]] process, a kind of natural [[grafting]] or welding of vegetal tissues. The tests to demonstrate this networking are performed by injecting chemicals, sometimes [[Radioactive decay|radioactive]], into a tree, and then checking for its presence in neighbouring trees.{{cite journal |last=Hough |first=Walter A. |title=Root extension of Individual trees in surface soils of a Natural Longleaf Pine-Turkey Oak Stand |journal=Forest Science |date=1 June 1965 |volume=11 |issue=2 |pages=223–242 |url=http://www.ingentaconnect.com/content/saf/fs/1965/00000011/00000002/art00020 |archive-url=https://web.archive.org/web/20131209062328/http://www.ingentaconnect.com/content/saf/fs/1965/00000011/00000002/art00020 |archive-date=9 December 2013 |url-status=dead }} [72] => [73] => The roots are, generally, an underground part of the tree, but some tree species have evolved roots that are [[aerial roots|aerial]]. The common purposes for aerial roots may be of two kinds, to contribute to the mechanical stability of the tree, and to obtain oxygen from air. An instance of mechanical stability enhancement is the [[Rhizophora mangle|red mangrove]] that develops [[buttress roots|prop roots]] that loop out of the trunk and branches and descend vertically into the mud.{{cite web |url=http://mangrove.nus.edu.sg/guidebooks/text/1043.htm |title=How plants cope in the mangroves |editor=Ng, Peter K. L. |editor2=Sivasothi, N. |year=2001 |work=Mangroves of Singapore |access-date=15 July 2012 |archive-date=22 May 2012 |archive-url=https://web.archive.org/web/20120522185105/http://mangrove.nus.edu.sg/guidebooks/text/1043.htm |url-status=live }} A similar structure is developed by the [[Ficus benghalensis|Indian banyan]].{{cite book |title=Trees: Their Natural History |last=Thomas |first=Peter |year=2000 |publisher=Cambridge University Press |isbn=978-0-521-45963-1 |page=108 |url=https://books.google.com/books?id=w6bUF8bOfKEC&pg=PA108 |access-date=29 May 2020 |archive-date=20 August 2020 |archive-url=https://web.archive.org/web/20200820005841/https://books.google.com/books?id=w6bUF8bOfKEC&pg=PA108 |url-status=live }} Many large trees have [[buttress root]]s which flare out from the lower part of the trunk. These brace the tree rather like angle brackets and provide stability, reducing sway in high winds. They are particularly prevalent in tropical rainforests where the soil is poor and the roots are close to the surface.{{cite journal |last1=Crook |first1=M. J. |author2=Ennos, A. R. |author3=Banks, J. R. |year=1997 |title=The function of buttress roots: a comparative study of the anchorage systems of buttressed (''Aglaia'' and ''Nephelium ramboutan'' species) and non-buttressed (''Mallotus wrayi'') tropical trees |journal=Journal of Experimental Botany |volume=48 |issue=9 |pages=1703–1716 |doi=10.1093/jxb/48.9.1703|doi-access=free }} [74] => [75] => Some tree species have developed root extensions that pop out of soil, in order to get oxygen, when it is not available in the soil because of excess water. These root extensions are called [[pneumatophores]], and are present, among others, in [[Avicennia germinans|black mangrove]] and pond cypress. [76] => [77] => ===Trunk=== [78] => [[File:Buk1.JPG|thumb|upright|Northern beech (''[[Fagus sylvatica]]'') trunk in autumn]] [79] => {{main|Trunk (botany)}} [80] => [81] => The main purpose of the trunk is to raise the leaves above the ground, enabling the tree to overtop other plants and outcompete them for light.{{cite journal |last1=King |first1=David A. |title=The Adaptive Significance of Tree Height |journal=The American Naturalist |volume=135 |issue=6 |year=1990 |pages=809–828 |doi=10.1086/285075 |s2cid=85160969 |quote=competition for light is the primary factor responsible for the evolution and maintenance of the arboreal life form. The resulting evolutionarily stable growth pattern maximizes the competitive ability of the individual }} It also transports water and nutrients from the roots to the aerial parts of the tree, and distributes the food produced by the leaves to all other parts, including the roots.{{cite book |title=The World Encyclopedia of Trees |last1=Russell |first1=Tony |author2=Cutler, Catherine |year=2003 |publisher=Lorenz Books |isbn=978-0-7548-1292-0 |pages=[https://archive.org/details/isbn_9780754812920/page/16 16–17] |url=https://archive.org/details/isbn_9780754812920/page/16 }} [82] => [83] => In the case of angiosperms and gymnosperms, the outermost layer of the trunk is the [[bark (botany)|bark]], mostly composed of dead cells of [[phellem]] (cork).{{cite journal |last1=Junikka |first1=Leo |title=Survey of English Macroscopic Bark Terminology |journal=IAWA Journal |volume=15 |issue=1 |year=1994 |pages=3–45 |doi=10.1163/22941932-90001338 |quote=phellem{{!}}a secondarily formed protective tissue in stems and roots consisting of dead cells with chiefly suberised walls: developed outward from the phellogen and forming a part of periderm|doi-access=free }} It provides a thick, waterproof covering to the living inner tissue. It protects the trunk against the elements, disease, animal attack and fire. It is perforated by a large number of fine breathing pores called [[lenticel]]s, through which oxygen diffuses. Bark is continually replaced by a living layer of cells called the [[cork cambium]] or phellogen. The [[Platanus × acerifolia|London plane]] (''Platanus × acerifolia'') periodically sheds its bark in large flakes. Similarly, the bark of the [[Betula pendula|silver birch]] (''Betula pendula'') peels off in strips. As the tree's girth expands, newer layers of bark are larger in circumference, and the older layers develop fissures in many species. In some trees such as the [[pine]] (''Pinus'' species) the bark exudes sticky [[resin]] which deters attackers whereas in [[Hevea brasiliensis|rubber trees]] (''Hevea brasiliensis'') it is a milky [[latex]] that oozes out. The [[Cinchona officinalis|quinine bark tree]] (''Cinchona officinalis'') contains bitter substances to make the bark unpalatable. Large tree-like plants with lignified trunks in the [[Pteridophyta]], [[Arecales]], [[Cycadophyta]] and [[Poales]] such as the tree ferns, palms, cycads and bamboos have different structures and outer coverings.{{cite book |title=Biology |last=Campbell |first=Neil A. |author2=Reece, Jane B. |year=2002 |publisher=Pearson Education |isbn=978-0-201-75054-6 |page=725|edition=6th }} [84] => [85] => [[File:Taxus wood.jpg|thumb|left|A section of [[Taxus baccata|yew]] (''Taxus baccata'') showing 27 annual growth rings, pale [[Sapwood (wood)|sapwood]] and dark [[heartwood]]]] [86] => [87] => Although the bark functions as a protective barrier, it is itself attacked by boring insects such as beetles. These lay their eggs in crevices and the larvae chew their way through the cellulose tissues leaving a gallery of tunnels. This may allow fungal spores to gain admittance and attack the tree. [[Dutch elm disease]] is caused by a fungus (''[[Ophiostoma]]'' species) carried from one [[elm]] tree to another by various beetles. The tree reacts to the growth of the fungus by blocking off the xylem tissue carrying sap upwards and the branch above, and eventually the whole tree, is deprived of nourishment and dies. In Britain in the 1990s, 25 million elm trees were killed by this disease.{{cite web |url=http://www.forestry.gov.uk/fr/HCOU-4U4JCL |title=Dutch elm disease in Britain |author=Webber, Joan |publisher=Forest Research |access-date=16 July 2012 |archive-date=9 March 2018 |archive-url=https://web.archive.org/web/20180309165010/https://www.forestry.gov.uk/fr/hcou-4u4jcl |url-status=dead }} [88] => [89] => The innermost layer of bark is known as the [[phloem]] and this is involved in the transport of the [[Plant sap|sap]] containing the sugars made by photosynthesis to other parts of the tree. It is a soft spongy layer of living cells, some of which are arranged end to end to form tubes. These are supported by [[parenchyma]] cells which provide padding and include fibres for strengthening the tissue.{{cite journal |author1=Lalonde, S. |author2=Wipf, D. |author3=Frommer, W. B. |year=2004 |title=Transport mechanisms for organic forms of carbon and nitrogen between source and sink |journal=Annual Review of Plant Biology |volume=55 |pages=341–372 |pmid=15377224 |doi=10.1146/annurev.arplant.55.031903.141758}} Inside the phloem is a layer of undifferentiated cells one cell thick called the vascular cambium layer. The cells are continually dividing, creating phloem cells on the outside and wood cells known as [[xylem]] on the inside.{{cite web |url=http://cronodon.com/BioTech/Plant_Bodies_Wood.html |title=Wood, tree trunks and branches |work=BioTech |publisher=Cronodon Museum |access-date=16 July 2012 |archive-date=2 May 2015 |archive-url=https://web.archive.org/web/20150502084356/http://cronodon.com/BioTech/Plant_Bodies_Wood.html |url-status=live }} [90] => [91] => The newly created xylem is the [[sapwood (wood)|sapwood]]. It is composed of water-conducting cells and associated cells which are often living, and is usually pale in colour. It transports water and minerals from the roots to the upper parts of the tree. The oldest, inner part of the sapwood is progressively converted into [[heartwood]] as new sapwood is formed at the cambium. The conductive cells of the heartwood are blocked in some species. Heartwood is usually darker in colour than the sapwood. It is the dense central core of the trunk giving it rigidity. Three quarters of the dry mass of the xylem is [[cellulose]], a [[polysaccharide]], and most of the remainder is lignin, a complex [[polymer]]. A transverse section through a tree trunk or a horizontal core will show concentric circles of lighter or darker wood – tree rings. These rings are the [[Growth rings|annual growth rings]]{{cite book |last=Fritts |first=H. C. |title=Tree Rings and Climate |publisher=Blackburn Press |year= 2001 |isbn=978-1-930665-39-2}}{{cite web |last1=Helama |first1=Samuel |last2=Jalkanen |first2=Risto |title=Annual growth rings of trees |url=https://www.luke.fi/en/natural-resources/forest/forests-and-climate-change/annual-growth-rings-of-trees/ |publisher=Natural Resources Institute Finland (LUKE) |access-date=17 July 2019 |archive-date=6 August 2019 |archive-url=https://web.archive.org/web/20190806043449/https://www.luke.fi/en/natural-resources/forest/forests-and-climate-change/annual-growth-rings-of-trees/ |url-status=live }} There may also be rays running at right angles to growth rings. These are [[Medullary ray (botany)|vascular rays]] which are thin sheets of living tissue permeating the wood.{{cite web |url=http://www.botany.uwc.ac.za/ecotree/trunk/woodanatomy2.htm |title=The anatomy of a tree trunk – the wood 2 |url-status=bot: unknown |archive-url=https://web.archive.org/web/20120314190054/http://www.botany.uwc.ac.za/ecotree/trunk/woodanatomy2.htm |archive-date=14 March 2012}} Many older trees may become hollow but may still stand upright for many years.{{cite web |url=http://cronodon.com/BioTech/Plant_Bodies_Wood.html |title=Xylem and wood |work=BioTech |publisher=Cronodon Museum |access-date=16 July 2012 |archive-date=2 May 2015 |archive-url=https://web.archive.org/web/20150502084356/http://cronodon.com/BioTech/Plant_Bodies_Wood.html |url-status=live }} [92] => [93] => ===Buds and growth=== [94] => {{stack begin}} [95] => [[File:Illustration Quercus robur0.jpg|thumb|upright|Buds, leaves, flowers and fruit of oak (''[[Quercus robur]]'')]] [96] => [[File:Illustration Abies alba0.jpg|thumb|upright|Buds, leaves and reproductive structures of white fir (''[[Abies alba]]'')]] [97] => [[File:Cycas circinalis(draw).jpg|thumb|upright|Form, leaves and reproductive structures of queen sago (''[[Cycas circinalis]]'')]] [98] => {{stack end}} [99] => {{main|Bud}} [100] => [101] => [[File:Magnolia Bud.jpg|thumb|left|Dormant ''[[Magnolia]]'' bud]] [102] => Trees do not usually grow continuously throughout the year but mostly have spurts of active expansion followed by periods of rest. This pattern of growth is related to climatic conditions; growth normally ceases when conditions are either too cold or too dry. In readiness for the inactive period, trees form [[bud]]s to protect the [[meristem]], the zone of active growth. Before the period of dormancy, the last few leaves produced at the tip of a twig form scales. These are thick, small and closely wrapped and enclose the growing point in a waterproof sheath. Inside this bud there is a rudimentary stalk and neatly folded miniature leaves, ready to expand when the next growing season arrives. Buds also form in the [[axil]]s of the leaves ready to produce new side shoots. A few trees, such as the [[eucalyptus]], have "naked buds" with no protective scales and some conifers, such as the [[Chamaecyparis lawsoniana|Lawson's cypress]], have no buds but instead have little pockets of meristem concealed among the scale-like leaves.{{cite book |title=The World Encyclopedia of Trees |last=Russell |first=Tony |author2=Cutler, Catherine |year=2003 |publisher=Lorenz Books |isbn=978-0-7548-1292-0 |pages=[https://archive.org/details/isbn_9780754812920/page/18 18–19] |url=https://archive.org/details/isbn_9780754812920/page/18 }} [103] => [104] => When growing conditions improve, such as the arrival of warmer weather and the longer days associated with spring in temperate regions, growth starts again. The expanding shoot pushes its way out, shedding the scales in the process. These leave behind scars on the surface of the twig. The whole year's growth may take place in just a few weeks. The new stem is unlignified at first and may be green and downy. The Arecaceae (palms) have their leaves spirally arranged on an unbranched trunk. In some tree species in temperate climates, a second spurt of growth, a [[Lammas growth]] may occur which is believed to be a strategy to compensate for loss of early foliage to insect predators.{{cite journal |journal=Journal of Experimental Botany |volume=54 |issue=389 |pages=1797–1799 |date=August 2003 |doi=10.1093/jxb/erg225 |title=August-learning about summer |last1=Battey |first1=N. H. |pmid=12869517|doi-access=free }} [105] => [106] => Primary growth is the elongation of the stems and roots. Secondary growth consists of a progressive thickening and strengthening of the tissues as the outer layer of the epidermis is converted into bark and the cambium layer creates new phloem and xylem cells. The bark is inelastic.{{cite book |title=Biology |last=Campbell |first=Neil A. |author2=Reece, Jane B. |year=2002 |publisher=Pearson Education |isbn=978-0-201-75054-6 |pages=729–730|edition=6th }} Eventually the growth of a tree slows down and stops and it gets no taller. If damage occurs the tree may in time become hollow.{{cite book |title=The World Encyclopedia of Trees |last=Russell |first=Tony |author2=Cutler, Catherine |year=2003 |publisher=Lorenz Books |isbn=978-0-7548-1292-0 |pages=[https://archive.org/details/isbn_9780754812920/page/16 16, 27] |url=https://archive.org/details/isbn_9780754812920/page/16 }} [107] => [108] => ===Leaves=== [109] => {{main|Leaf}} [110] => [111] => Leaves are structures specialised for photosynthesis and are arranged on the tree in such a way as to maximise their exposure to light without shading each other. They are an important investment by the tree and may be thorny or contain [[phytolith]]s, [[lignin]]s, [[tannin]]s or [[poison]]s to discourage herbivory. Trees have evolved leaves in a wide range of shapes and sizes, in response to environmental pressures including climate and predation. They can be broad or needle-like, simple or compound, lobed or entire, smooth or hairy, delicate or tough, deciduous or evergreen. The needles of coniferous trees are compact but are structurally similar to those of broad-leaved trees. They are adapted for life in environments where resources are low or water is scarce. Frozen ground may limit water availability and conifers are often found in colder places at higher altitudes and higher latitudes than broad leaved trees. In conifers such as fir trees, the branches hang down at an angle to the trunk, enabling them to shed snow. In contrast, broad leaved trees in temperate regions deal with winter weather by shedding their leaves. When the days get shorter and the temperature begins to decrease, the leaves no longer make new [[chlorophyll]] and the red and yellow pigments already present in the blades become apparent.{{cite book |author=Pessarakli, Mohammad |title=Handbook of Photosynthesis |url=https://books.google.com/books?id=0_3XqlcKPpwC&pg=PA725 |year=2005 |publisher=CRC Press |isbn=978-0-8247-5839-4 |pages=717–739 |access-date=28 February 2016 |archive-date=21 May 2016 |archive-url=https://web.archive.org/web/20160521021252/https://books.google.com/books?id=0_3XqlcKPpwC&pg=PA725 |url-status=live }} Synthesis in the leaf of a [[plant hormone]] called [[auxin]] also ceases. This causes the cells at the junction of the [[Petiole (botany)|petiole]] and the twig to weaken until the joint breaks and the leaf floats to the ground. In tropical and subtropical regions, many trees keep their leaves all year round. Individual leaves may fall intermittently and be replaced by new growth but most leaves remain intact for some time. Other tropical species and those in arid regions may shed all their leaves annually, such as at the start of the dry season.{{cite book |url=https://books.google.com/books?id=_16xbB2Py_UC&pg=PA734 |title=Biology: Concepts and Applications |author1=Starr, Cecie |author2=Evers, Christine |author3=Starr, Lisa |publisher=Cengage Learning |date=2010 |page=734 |isbn=978-1-4390-4673-9 |access-date=28 February 2016 |archive-date=19 March 2022 |archive-url=https://web.archive.org/web/20220319090500/https://books.google.com/books?id=_16xbB2Py_UC&pg=PA734 |url-status=live }} Many deciduous trees flower before the new leaves emerge.{{cite journal |first=Stephen H. |last=Bullock |author2=Solis-Magallanes, J. Arturo |title=Phenology of canopy trees of a tropical deciduous forest in Mexico |journal=Biotropica |volume=22 |issue=1 |date=March 1990 |pages=22–35 |doi=10.2307/2388716 |jstor=2388716|bibcode=1990Biotr..22...22B }} A few trees do not have true leaves but instead have structures with similar external appearance such as [[Phylloclade]]s – [[Aerial stem modification|modified stem]] structures{{Cite book |last=Beentje |first=Henk |year=2010 |title=The Kew Plant Glossary |location=Richmond, Surrey |publisher=[[Royal Botanic Gardens, Kew]] |isbn=978-1-84246-422-9}} p. 87. – as seen in the genus ''[[Phyllocladus]]''.Page, Christopher N. (1990). "Phyllocladaceae" pp. 317–319. In: Klaus Kubitzki (general editor); Karl U. Kramer and Peter S. Green (volume editors) ''The Families and Genera of Vascular Plants'' volume I. Springer-Verlag: Berlin; Heidelberg, Germany. {{ISBN|978-0-387-51794-0}} [112] => [113] => ===Reproduction=== [114] => {{further|Plant reproduction|Pollination|Seed dispersal}} [115] => [116] => Trees can be [[Pollination|pollinated]] either by wind or by animals, mostly insects. Many angiosperm trees are insect pollinated. Wind pollination may take advantage of increased wind speeds high above the ground.{{cite web |url=http://www.treesforlife.org.uk/forest/ecological/pollination.html |title=Pollination |publisher=Trees for Life |access-date=14 November 2017 |archive-date=6 October 2014 |archive-url=https://web.archive.org/web/20141006130745/http://www.treesforlife.org.uk/forest/ecological/pollination.html |url-status=live }} Trees use a variety of methods of [[seed dispersal]]. Some rely on wind, with winged or plumed seeds. Others rely on animals, for example with edible fruits. Others again eject their seeds (ballistic dispersal), or use gravity so that seeds fall and sometimes roll.{{cite journal |last1=Nathan |first1=Ran |author1-link=Ran Nathan |last2=Seidler |first2=Tristram G. |author-link2=Tristram G. Seidler|last3=Plotkin |first3=Joshua B. |author-link3=Joshua B. Plotkin |title=Seed Dispersal and Spatial Pattern in Tropical Trees |journal=PLOS Biology |volume=4 |issue=11 |year=2006 |pages=e344 |doi=10.1371/journal.pbio.0040344|pmid=17048988 |pmc=1609130 |doi-access=free }} [117] => [118] => ===Seeds=== [119] => {{main|Seed}} [120] => [121] => Seeds are the primary way that trees reproduce and their seeds vary greatly in size and shape. Some of the largest seeds come from trees, but the largest tree, ''[[Sequoiadendron giganteum]]'', produces one of the smallest tree seeds.{{cite book |last=Walker |first=Laurence C. |title=Forests: A Naturalist's Guide to Woodland Trees |url=https://books.google.com/books?id=LNJqY52pdSwC&pg=PA56 |year=1997 |publisher=University of Texas Press |isbn=978-0-292-79112-1 |page=56 |access-date=28 February 2016 |archive-date=4 March 2017 |archive-url=https://web.archive.org/web/20170304153834/https://books.google.com/books?id=LNJqY52pdSwC&pg=PA56 |url-status=live }} The great diversity in tree fruits and seeds reflects the many different ways that tree species have evolved to [[Seed dispersal|disperse]] their offspring. [122] => [123] => [[File:Samara olmo frassino acero.png|thumb|left|Wind dispersed seed of elm (''[[Ulmus]]''), ash (''[[Fraxinus]]'') and maple (''[[Acer (plant)|Acer]]'')]] [124] => [125] => For a tree seedling to grow into an adult tree it needs light. If seeds only fell straight to the ground, competition among the concentrated saplings and the shade of the parent would likely prevent it from flourishing. Many seeds such as [[birch]] are small and have papery wings to aid dispersal by the wind. [[Ash (Fraxinus)|Ash]] trees and [[maple]]s have larger seeds with blade shaped wings which spiral down to the ground when released. The [[Ceiba pentandra|kapok]] tree has cottony threads to catch the breeze.{{cite web |url=http://www.vtaide.com/png/seed-dispersion.htm |title=How seeds are dispersed |last1=Meng |first1=Alan |author2=Meng, Hui |work=Interactive Assessment Worksheets |access-date=23 July 2012 |archive-date=5 August 2012 |archive-url=https://web.archive.org/web/20120805115217/http://www.vtaide.com/png/seed-dispersion.htm |url-status=live }} [126] => [127] => The seeds of conifers, the largest group of gymnosperms, are enclosed in a cone and most species have seeds that are light and papery that can be blown considerable distances once free from the cone.{{cite book |last1=Evert |first1=Ray F. |author2=Eichhorn, Susan E. |title=Biology of Plants |url=https://books.google.com/books?id=8tz2aB1-jb4C&pg=PA422 |year=2004 |publisher=Macmillan |isbn=978-0-7167-1007-3 |page=422 |access-date=28 February 2016 |archive-date=4 March 2017 |archive-url=https://web.archive.org/web/20170304154119/https://books.google.com/books?id=8tz2aB1-jb4C&pg=PA422 |url-status=live }} Sometimes the seed remains in the cone for years waiting for a trigger event to liberate it. Fire stimulates release and germination of seeds of the [[jack pine]], and also enriches the forest floor with wood ash and removes competing vegetation.{{cite web |url=http://www.zephyrus.co.uk/firedispersal.html |title=Fire |last1=Parkin |first1=Dave |author2=Parkin, Marilyn |work=How do the seeds disperse to form new plants? |publisher=Zephyrus |access-date=23 July 2012 |archive-date=22 June 2012 |archive-url=https://web.archive.org/web/20120622181841/http://www.zephyrus.co.uk/firedispersal.html |url-status=live }} Similarly, a number of angiosperms including ''[[Acacia cyclops]]'' and ''[[Acacia mangium]]'' have seeds that germinate better after exposure to high temperatures.{{cite book |author1=Baskin, Carol C. |author2=Baskin, Jerry M. |title=Seeds: Ecology, Biogeography, and Evolution of Dormancy and Germination |url=https://books.google.com/books?id=uGJL_Ys6wlQC&pg=PA121 |year=2001 |publisher=Elsevier |isbn=978-0-12-080263-0 |pages=121, 260 |access-date=28 February 2016 |archive-date=22 December 2016 |archive-url=https://web.archive.org/web/20161222054555/https://books.google.com/books?id=uGJL_Ys6wlQC&pg=PA121 |url-status=live }} [128] => [129] => The [[Delonix regia|flame tree]] ''Delonix regia'' does not rely on fire but shoots its seeds through the air when the two sides of its long pods crack apart explosively on drying. The miniature cone-like catkins of [[alder]] trees produce seeds that contain small droplets of oil that help disperse the seeds on the surface of water. Mangroves often grow in water and some species have [[propagule]]s, which are buoyant fruits with seeds that start germinating before becoming detached from the parent tree.{{cite book |author1=Barbour, Michael G. |author2=Billings, William Dwight |title=North American Terrestrial Vegetation |url=https://books.google.com/books?id=Ra2QzAh9xdIC&pg=PA528 |year=1999 |publisher=Cambridge University Press |isbn=978-0-521-55986-7 |page=528 |access-date=28 February 2016 |archive-date=22 December 2016 |archive-url=https://web.archive.org/web/20161222052706/https://books.google.com/books?id=Ra2QzAh9xdIC&pg=PA528 |url-status=live }}{{cite web |url=http://www.naturefoundationsxm.org/education/mangroves/the_white_mangrove.htm |title=The White Mangrove |publisher=Nature Foundation, St. Maarten |author=van der Neut, Marcus |work=naturefoundationsxm.org |url-status=dead |archive-url=https://web.archive.org/web/20120125214433/http://www.naturefoundationsxm.org/education/mangroves/the_white_mangrove.htm |archive-date=25 January 2012 }} These float on the water and may become lodged on emerging mudbanks and successfully take root. [130] => [131] => [[File:Gebarsten bolster van een paardenkastanje (Aesculus) 20-09-2020 (d.j.b.) 01.jpg|thumb|Cracked [[Thorns, spines, and prickles|thorny]] skin of a [[Aesculus tree]] seed|upright]] [132] => Other seeds, such as apple pips and plum stones, have fleshy receptacles and smaller fruits like [[Crataegus|hawthorns]] have seeds enclosed in edible tissue; animals including mammals and birds eat the fruits and either discard the seeds, or swallow them so they pass through the gut to be deposited in the animal's droppings well away from the parent tree. The germination of some seeds is improved when they are processed in this way.{{cite web |url=http://www.webpages.uidaho.edu/range556/appl_behave/projects/seed_dispersal.html |title=Seed Dispersal by Animals: Behavior Matters |author=Yang, Suann |work=BEHAVE: Behavioral Education for Human, Animal, Vegetation and Ecosystem Management |access-date=23 July 2012 |archive-date=9 December 2013 |archive-url=https://web.archive.org/web/20131209043548/http://www.webpages.uidaho.edu/range556/appl_behave/projects/seed_dispersal.html |url-status=live }} [[Nut (fruit)|Nuts]] may be gathered by animals such as squirrels that [[hoarding (animal behavior)|cache]] any not immediately consumed.{{cite book |author1=Levey, Douglas J. |author2=Silva, Wesley R. |author3=Galetti, Mauro |title=Seed Dispersal and Frugivory: Ecology, Evolution and Conservation |url=https://books.google.com/books?id=sU7213gPmDMC&pg=PA206 |year=2002 |publisher=CABI |isbn=978-0-85199-525-0 |page=206 |access-date=28 February 2016 |archive-date=4 March 2017 |archive-url=https://web.archive.org/web/20170304160055/https://books.google.com/books?id=sU7213gPmDMC&pg=PA206 |url-status=live }} Many of these caches are never revisited, the nut-casing softens with rain and frost, and the seed germinates in the spring.{{cite journal |author1=Ruxton, Graeme D. |author1-link=Graeme Ruxton |author2=Schaefer, H. Martin |year=2012 |title=The conservation physiology of seed dispersal | journal=Philosophical Transactions of the Royal Society | volume=367 | issue=1596 | pages=1708–1718 | doi=10.1098/rstb.2012.0001 |pmid=22566677 |pmc=3350653 |doi-access=free}} Pine cones may similarly be hoarded by [[red squirrel]]s, and [[grizzly bear]]s may help to disperse the seed by raiding squirrel caches.{{cite web |url=http://www.webpages.uidaho.edu/range556/Appl_BEHAVE/projects/whitebark_pine.html |title=Whitebark Pine Seeds, Red Squirrels, and Grizzly Bears: An Interconnected Relationship |author=Sager, Kim |work=BEHAVE: Behavioral Education for Human, Animal, Vegetation and Ecosystem Management |access-date=23 July 2012 |archive-date=9 December 2013 |archive-url=https://web.archive.org/web/20131209043552/http://www.webpages.uidaho.edu/range556/Appl_BEHAVE/projects/whitebark_pine.html |url-status=live }} [133] => [134] => The single extant species of Ginkgophyta (''Ginkgo biloba'') has fleshy seeds produced at the ends of short branches on female trees,{{cite web |url=http://faculty.unlv.edu/landau/gymnosperms.htm |title=Gymnosperms |work=unlv.edu |access-date=27 September 2012 |archive-date=9 October 2012 |archive-url=https://web.archive.org/web/20121009024559/http://faculty.unlv.edu/landau/gymnosperms.htm |url-status=live }} and ''[[Gnetum]]'', a tropical and subtropical group of gymnosperms produce seeds at the tip of a shoot axis.{{cite book |author1=Bhatnagar, S. P. |author2=Moitra, Alok |title=Gymnosperms |url=https://books.google.com/books?id=4dvyNckni8wC&pg=PA371 |year=1996 |publisher=New Age International |isbn=978-81-224-0792-1 |page=371 |access-date=28 February 2016 |archive-date=4 March 2017 |archive-url=https://web.archive.org/web/20170304152805/https://books.google.com/books?id=4dvyNckni8wC&pg=PA371 |url-status=live }} [135] => [136] => ==Evolutionary history== [137] => [[File:PSM V18 D630 Restoration of a lepidodendron.jpg|thumb|upright|''[[Lepidodendron]]'', an extinct [[Lycopodiophyta|lycophyte]] tree]] [138] => [[File:PSM V16 D476 Principal palms and cycadeae of middle tertiary europe.jpg|thumb|upright|Palms and cycads as they might have appeared in the middle [[Tertiary era|Tertiary]]]] [139] => {{further | Evolutionary history of plants}} [140] => [141] => The earliest trees were [[tree fern]]s, [[horsetail]]s and [[lycophytes]], which grew in forests in the [[Carboniferous]] period. The first tree may have been ''[[Wattieza]]'', fossils of which were found in [[New York (state)|New York state]] in 2007 dating back to the [[Middle Devonian]] (about 385 million years ago). Prior to this discovery, ''[[Archaeopteris]]'' was the earliest known tree.{{cite journal |doi=10.2307/2805124 |author=Beck, Charles B. |year=1960 |title=The identity of ''Archaeopteris'' and ''Callixylon'' |journal=Brittonia |volume=12 |issue=4 |pages=351–368 |jstor=2805124|bibcode=1960Britt..12..351B |s2cid=27887887 }} Both of these reproduced by spores rather than seeds and are considered to be links between ferns and the gymnosperms which evolved in the [[Triassic]] period. The gymnosperms include conifers, cycads, gnetales and [[ginkgo]]s and these may have appeared as a result of a [[Gene duplication#As an evolutionary event|whole genome duplication event]] which took place about 319 million years ago.{{cite journal |author=Jiao, Y. |author2=Wickett, N. J. |author3=Ayyampalayam, S. |author4=Chanderbali, A. S. |author5=Landherr, L. |author6=Ralph, P. E. |author7=Tomsho, L. P. |author8=Hu, Y. |author9=Liang, H. |author10-link=Soltis, P. S |author10=Soltis, P. S. |author11=Soltis, D. E. |author12=Clifton, S. W. |author13=Schlarbaum, S. E. |author14=Schuster, S. C. |author15=Ma, H. |author16=Leebens-Mack, J. |author17=dePamphilis, C. W. |display-authors=3 |year=2011 |title=Ancestral polyploidy in seed plants and angiosperms |journal=Nature |volume=473 |issue=7345 |pages=97–100 |doi=10.1038/nature09916 |pmid=21478875|bibcode=2011Natur.473...97J |s2cid=4313258 }} [[Ginkgophyta]] was once a widespread diverse group{{cite journal |author=Gnaedinger, Silvia |year=2012 |title=Ginkgoalean woods from the Jurassic of Argentina: Taxonomic considerations and palaeogeographical distribution |journal=Geobios |volume=45 |issue=2 |pages=187–198 |doi=10.1016/j.geobios.2011.01.007|bibcode=2012Geobi..45..187G |hdl=11336/25674 |hdl-access=free }} of which the only survivor is the maidenhair tree ''[[Ginkgo biloba]]''. This is considered to be a [[living fossil]] because it is virtually unchanged from the fossilised specimens found in Triassic deposits.{{cite web |url=http://www.ucmp.berkeley.edu/IB181/VPL/CorCon/CorCon2.html |title=''Ginkgo'' |author=Arens, Nan C. |year=1998 |work=Lab IX; Ginkgo, Cordaites and the Conifers |publisher=University of California Museum of Paleontology |access-date=25 July 2012 |archive-date=4 July 2017 |archive-url=https://web.archive.org/web/20170704102225/http://www.ucmp.berkeley.edu/IB181/VPL/CorCon/CorCon2.html |url-status=live }} [142] => [143] => During the Mesozoic (245 to 66 million years ago) the conifers flourished and became adapted to live in all the major terrestrial habitats. Subsequently, the tree forms of [[flowering plant]]s evolved during the [[Cretaceous]] period. These began to [[dominance (ecology)|displace]] the conifers during the [[Tertiary]] era (66 to 2 million years ago) when forests covered the globe. When the climate cooled 1.5 million years ago and the first of four [[Glacial period|glacial periods]] occurred, the forests retreated as the ice advanced. In the [[interglacial]]s, trees recolonised the land that had been covered by ice, only to be driven back again in the next glacial period.{{cite web |url=http://www.rfs.org.uk/learning/forestry-knowledge-hub/trees-biology/tree-evolution/ |title=Tree evolution |year=2012 |work=Tree Biology |publisher=Royal Forestry Society |access-date=25 July 2012 |archive-date=23 October 2016 |archive-url=https://web.archive.org/web/20161023054737/http://www.rfs.org.uk/learning/forestry-knowledge-hub/trees-biology/tree-evolution/ |url-status=live }} [144] => [145] => ==Ecology== [146] => {{further|Forest}} [147] => [148] => Trees are an important part of the terrestrial [[ecosystem]],{{cite journal |last=Lowman |first=M D |title=Canopy research in the twenty-first century: a review of arboreal ecology |journal=Tropical Ecology |volume=50 |year=2009 |pages=125–136 |issn=0564-3295}} providing essential habitats including many kinds of forest for communities of organisms. [[Epiphyte|Epiphytic]] plants such as [[fern]]s, some mosses, liverworts, [[orchid]]s and some species of [[parasite|parasitic]] plants (e.g., [[mistletoe]]) hang from branches;{{cite book |last=Zotz |first=Gerhard |title=Plants on Plants – The Biology of Vascular Epiphytes |url=https://books.google.com/books?id=hIP2DAAAQBAJ |year=2016 |publisher=Springer |isbn=978-3-319-39237-0 |access-date=14 November 2017 |archive-date=19 August 2020 |archive-url=https://web.archive.org/web/20200819114740/https://books.google.com/books?id=hIP2DAAAQBAJ |url-status=live }} these along with arboreal lichens, algae, and fungi provide micro-habitats for themselves and for other organisms, including animals. Leaves, flowers and fruits are seasonally available. On the ground underneath trees there is shade, and often there is undergrowth, [[leaf litter]], and decaying wood that provide other habitat.{{cite web|title=The structure of a forest|url=http://enviropol.com/index.php/forest-structure|publisher=Enviropol|access-date=14 November 2017|archive-date=15 November 2017|archive-url=https://web.archive.org/web/20171115083431/http://enviropol.com/index.php/forest-structure|url-status=live}}{{cite web|title=Forest Layers, Stories, And Stratification|url=http://www.worldatlas.com/articles/forest-layers-stories-and-stratification.html|publisher=WorldAtlas|access-date=14 November 2017|archive-date=15 November 2017|archive-url=https://web.archive.org/web/20171115083445/http://www.worldatlas.com/articles/forest-layers-stories-and-stratification.html|url-status=live}} Trees stabilise the soil, prevent rapid run-off of rain water, help prevent desertification, have a role in climate control and help in the maintenance of [[biodiversity]] and ecosystem balance.{{cite web |url=http://www.fao.org/docrep/005/y2328e/y2328e00.htm |title=Trees outside forests |author1=Bellefontaine, R. |author2=Petit, S. |author3=Pain-Orcet, M. |author4=Deleporte, P. |author5=Bertault, J-G |year=2002 |publisher=Food and Agriculture Organization of the United Nations |access-date=25 July 2012 |archive-date=31 January 2019 |archive-url=https://web.archive.org/web/20190131070800/http://www.fao.org/docrep/005/Y2328E/y2328e00.htm |url-status=live }} [149] => [150] => Many species of tree support their own specialised [[invertebrate]]s. In their natural habitats, 284 different species of insect have been found on the English oak (''[[Quercus robur]]''){{cite web |url=http://www.oldknobbley.com/woodland_ecology/trees/trees_oak_english.php |title=English oak |year=2007 |work=Old Knobbley |access-date=25 July 2012 |url-status=dead |archive-url=https://web.archive.org/web/20120908010458/http://www.oldknobbley.com/woodland_ecology/trees/trees_oak_english.php |archive-date=8 September 2012}} and 306 species of invertebrate on the Tasmanian oak (''[[Eucalyptus obliqua]]'').{{cite web |url=http://www.outreachecology.com/go/deliver/YoavDanielBarNessICE2004.pdf |title=Tiny animals, titan trees |author=Bar-Ness, Yoav Daniel |year=2004 |work=ICE: Canopy Invertebrate Fauna of Tasmanian Eucalyptus obliqua |access-date=25 July 2012 |url-status=dead |archive-url=https://web.archive.org/web/20121204021347/http://www.outreachecology.com/go/deliver/YoavDanielBarNessICE2004.pdf |archive-date=4 December 2012 }} Non-native tree species provide a less biodiverse community, for example in the United Kingdom the sycamore (''[[Acer pseudoplatanus]]''), which originates from southern Europe, has few associated invertebrate species, though its bark supports a wide range of lichens, bryophytes and other epiphytes.{{cite web |url=http://members.multimania.co.uk/WoodyPlantEcology/docs/QJF87-143.pdf |archive-url=https://web.archive.org/web/20130221090223/http://members.multimania.co.uk/WoodyPlantEcology/docs/QJF87-143.pdf |archive-date=21 February 2013 |title=The conservation value of sycamore |author=Binggeli, Pierre |access-date=25 July 2012 |url-status=dead}} {{anchor|Tree apparency}}Trees differ ecologically in the ease with which they can be found by herbivores. Tree apparency varies with a tree's size and [[semiochemical]] content, and with the extent to which it is concealed by [[nonhost resistance|nonhost]] neighbours from its [[insect herbivore|insect pests]].{{cite journal | last1=Jactel | first1=Hervé | last2=Moreira | first2=Xoaquín | last3=Castagneyrol | first3=Bastien | title=Tree Diversity and Forest Resistance to Insect Pests: Patterns, Mechanisms, and Prospects | journal=[[Annual Review of Entomology]] | publisher=[[Annual Reviews (publisher)|Annual Reviews]] | volume=66 | issue=1 | date=7 January 2021 |doi=10.1146/annurev-ento-041720-075234 |pages=277–296| pmid=32903046 | s2cid=221621050 | doi-access=free }} [151] => [152] => In ecosystems such as mangrove swamps, trees play a role in developing the habitat, since the roots of the mangrove trees reduce the speed of flow of tidal currents and trap water-borne sediment, reducing the water depth and creating suitable conditions for further mangrove colonisation. Thus mangrove swamps tend to extend seawards in suitable locations.{{cite web |url=http://ocw.unu.edu/international-network-on-water-environment-and-health/unu-inweh-course-1-mangroves/Importance-of-mangroves.pdf |archive-url=https://web.archive.org/web/20140904153735/http://ocw.unu.edu/international-network-on-water-environment-and-health/unu-inweh-course-1-mangroves/Importance-of-mangroves.pdf |archive-date=4 September 2014 |title=Importance of Mangrove Ecosystem |last=Kathiresan |first=K. |publisher=Annamalai University |access-date=6 September 2014 |url-status=dead}} Mangrove swamps also provide an effective buffer against the more damaging effects of cyclones and tsunamis.{{cite web |url=http://www.nepa.gov.jm/policies/draft/Mangroves%20and%20Coastal%20Wetland%20Protection/MANGROVE%20AND%20COASTAL%20WETLANDS%20PROTECTION%20part%201%20to%203.htm |title=Mangroves and coastal wetlands protection |publisher=University of Jamaica |access-date=6 September 2014 |archive-date=23 November 2020 |archive-url=https://web.archive.org/web/20201123124810/https://www.nepa.gov.jm/policies/draft/Mangroves%20and%20Coastal%20Wetland%20Protection/MANGROVE%20AND%20COASTAL%20WETLANDS%20PROTECTION%20part%201%20to%203.htm |url-status=live }} [153] => [154] => ==Uses== [155] => [156] => ===Food=== [157] => {{further|nut (fruit)|fruit}} [158] => [159] => Trees are the source of many of the world's best known fleshy fruits. Apples, pears, plums, cherries and citrus are all grown commercially in temperate climates and a wide range of edible fruits are found in the tropics. Other commercially important fruit include dates, figs and olives. [[Palm oil]] is obtained from the fruits of the oil palm (''[[Elaeis guineensis]]''). The fruits of the cocoa tree (''[[Theobroma cacao]]'') are used to make [[cocoa solids|cocoa]] and chocolate and the berries of coffee trees, ''[[Coffea arabica]]'' and ''[[Coffea canephora]]'', are processed to extract the coffee beans. In many rural areas of the world, fruit is gathered from forest trees for consumption.{{cite web |url=http://www.fao.org/docrep/X5325e/x5325e0c.htm |title=Monetary valuation of tree-based resources in Zimbabwe |author=Campbell, B. |year=1993 |publisher=FAO: Forestry Department |access-date=13 September 2012 |archive-date=1 May 2013 |archive-url=https://web.archive.org/web/20130501225016/http://www.fao.org/docrep/X5325e/x5325e0c.htm |url-status=live }} Many trees bear edible nuts which can loosely be described as being large, oily kernels found inside a hard shell. These include [[coconut]]s (''Cocos nucifera''), [[Brazil nut]]s (''Bertholletia excelsa''), [[pecan]]s (''Carya illinoinensis''), [[Hazel|hazel nuts]] (''Corylus''), [[almond]]s (''Prunus dulcis''), [[walnut]]s (''Juglans regia''), [[pistachio]]s (''Pistacia vera'') and many others. They are high in nutritive value and contain high-quality protein, vitamins and minerals as well as dietary fibre.{{cite news |title=Walnuts are the healthiest nut, say scientists |url=https://www.bbc.co.uk/news/health-12865291 |newspaper=BBC News: Health |date=28 March 2011 |access-date=21 September 2014 |archive-date=24 September 2017 |archive-url=https://web.archive.org/web/20170924113046/http://www.bbc.co.uk/news/health-12865291 |url-status=live }} A variety of [[List of vegetable oils#Nut oils|nut oils]] are extracted by pressing for culinary use; some such as walnut, pistachio and hazelnut oils are prized for their distinctive flavours, but they tend to spoil quickly.{{cite book |url=https://archive.org/details/isbn_9780740769764 |url-access=registration |title=Things Cooks Love |author=Simmons, Marie |publisher=Andrews McMeel |year=2008 |page=[https://archive.org/details/isbn_9780740769764/page/295 295] |isbn=978-0-7407-6976-4}} [160] => [161] => [[File:Maple syrup taps.jpg|thumb|left|Sugar maple (''[[Acer saccharum]]'') tapped to collect sap for [[maple syrup]]]] [162] => [163] => In temperate climates there is a sudden movement of sap at the end of the winter as trees prepare to burst into growth. In North America, the sap of the sugar maple (''[[Acer saccharum]]'') is most often used in the production of a sweet liquid, [[maple syrup]]. About 90% of the sap is water, the remaining 10% being a mixture of various sugars and certain minerals. The sap is harvested by drilling holes in the trunks of the trees and collecting the liquid that flows out of the inserted spigots. It is piped to a sugarhouse where it is heated to concentrate it and improve its flavour. Similarly in northern Europe the spring rise in the [[Birch sap|sap]] of the silver birch (''Betula pendula'') is tapped and collected, either to be drunk fresh or fermented into an alcoholic drink. In Alaska, the sap of the sweet birch (''[[Betula lenta]]'') is made into a syrup with a sugar content of 67%. Sweet birch sap is more dilute than maple sap; a hundred litres are required to make one litre of birch syrup.{{cite web |url=http://www.alaskabirchsyrup.com/abbisy.html |title=About birch syrup |publisher=Alaska Wild Harvest |access-date=27 July 2012 |url-status=dead |archive-url=https://web.archive.org/web/20120815013022/http://www.alaskabirchsyrup.com/abbisy.html |archive-date=15 August 2012 }} [164] => [165] => Various parts of trees are used as spices. These include [[cinnamon]], made from the bark of the cinnamon tree (''[[Cinnamomum zeylanicum]]'') and [[allspice]], the dried small fruits of the pimento tree (''[[Pimenta dioica]]''). [[Nutmeg]] is a seed found in the fleshy fruit of the nutmeg tree (''[[Myristica fragrans]]'') and [[clove]]s are the unopened flower buds of the clove tree (''[[Syzygium aromaticum]]''). [166] => [167] => Many trees have flowers rich in [[nectar]] which are attractive to bees. The production of forest honey is an important industry in rural areas of the developing world where it is undertaken by small-scale beekeepers using traditional methods.{{cite web |url=http://www.tropicalforest.com/Tropical_Forest/Tropical_Forest_home.html |archive-url=https://web.archive.org/web/20111015230522/http://www.tropicalforest.com/Tropical_Forest/Tropical_Forest_home.html |archive-date=15 October 2011 |title=Honey |publisher=Tropical Forest |access-date=28 July 2012 |url-status=dead }} The flowers of the elder (''[[Sambucus]]'') are used to make [[elderflower cordial]] and petals of the plum (''[[Prunus]] spp.'') can be candied.{{cite web |url=http://extension.colostate.edu/topic-areas/yard-garden/edible-flowers-7-237/ |title=Edible flowers |author1=Newman, S. E. |author2=O'Connor, A. Stoven |date=November 2009 |publisher=Colorado State University Extension |access-date=28 July 2012 |archive-date=11 October 2015 |archive-url=https://web.archive.org/web/20151011151626/http://extension.colostate.edu/topic-areas/yard-garden/edible-flowers-7-237/ |url-status=live }} [[Sassafras]] oil is a flavouring obtained from distilling bark from the roots of the sassafras tree (''[[Sassafras albidum]]''). [168] => [169] => The leaves of trees are widely gathered as fodder for livestock and some can be eaten by humans but they tend to be high in tannins which makes them bitter. Leaves of the curry tree (''[[Murraya koenigii]]'') are eaten, those of [[kaffir lime]] (''Citrus × hystrix'') (in [[Thai food]]){{cite web |last=Loha-unchit |first=Kasma |title=Kaffir Lime: Magrood |work=Thai Food and Travel |url=http://www.thaifoodandtravel.com/ingredients/klime.html |access-date=16 May 2012 |archive-date=9 May 2019 |archive-url=https://web.archive.org/web/20190509021529/http://www.thaifoodandtravel.com/ingredients/klime.html |url-status=live }} and ''[[Ailanthus]]'' (in [[Korean food|Korean]] dishes such as [[bugak]]) and those of the European bay tree (''[[Laurus nobilis]]'') and the California bay tree (''[[Umbellularia californica]]'') are used for flavouring food.{{cite web |url=http://waynesword.palomar.edu/ecoph16.htm |title=Allspice, Bay Rum, Bay Leaves, Capers, Cloves, Cinnamon, Camphor, Witch Hazel & Nutmeg |last=Armstrong |first=Wayne P. |date=1 June 2012 |work=Wayne's Word |access-date=28 July 2012 |archive-date=10 August 2012 |archive-url=https://web.archive.org/web/20120810131037/http://waynesword.palomar.edu/ecoph16.htm |url-status=live }} ''[[Camellia sinensis]]'', the source of tea, is a small tree but seldom reaches its full height, being heavily pruned to make picking the leaves easier.{{cite web |url=http://www.upasitearesearch.org/tea-cultivation-practices/ |title=Tea cultivation and practices |publisher=Upasi Tea Research Foundation |access-date=13 September 2012 |archive-date=17 October 2012 |archive-url=https://web.archive.org/web/20121017032147/http://www.upasitearesearch.org/tea-cultivation-practices/ |url-status=live }} [170] => [171] => [[Smoking (cooking)|Wood smoke]] can be used to preserve food. In the hot smoking process the food is exposed to smoke and heat in a controlled environment. The food is ready to eat when the process is complete, having been tenderised and flavoured by the smoke it has absorbed. In the cold process, the temperature is not allowed to rise above {{convert | 100 | °F | °C | abbr=on}}. The flavour of the food is enhanced but raw food requires further cooking. If it is to be preserved, meat should be [[Curing (food preservation)|cured]] before cold smoking.{{cite news |title=The rise and rise of smoking food |last=Mackenzie |first=Sophie |url=https://www.theguardian.com/lifeandstyle/wordofmouth/2012/jan/30/rise-of-smoking-food |newspaper=The Guardian |date=30 January 2012 |access-date=27 July 2012 |location=London |archive-date=4 March 2016 |archive-url=https://web.archive.org/web/20160304052854/http://www.theguardian.com/lifeandstyle/wordofmouth/2012/jan/30/rise-of-smoking-food |url-status=live }} [172] => [173] => ===Fuel=== [174] => {{main | Wood fuel}} [175] => [[File:Selling fuelwood.jpeg|thumb|Selling firewood at a market]] [176] => [177] => Wood has traditionally been used for fuel, especially in rural areas. In less developed nations it may be the only fuel available and collecting firewood is often a time-consuming task as it becomes necessary to travel further and further afield in the search for fuel.{{cite web |url=https://www.un.org/womenwatch/feature/idrw/index-2008.html |title=Women watch: International Day of Rural Women |date=15 October 2008 |publisher=United Nations Inter-agency Network on Women and Gender Equality |access-date=1 August 2012 |archive-date=17 December 2011 |archive-url=https://web.archive.org/web/20111217142532/http://www.un.org/womenwatch/feature/idrw/index-2008.html |url-status=live }} It is often burned inefficiently on an open fire. In more developed countries other fuels are available and burning wood is a choice rather than a necessity. Modern [[wood-burning stove]]s are very fuel efficient and new products such as [[wood pellet]]s are available to burn.{{cite web |url=http://www.epa.gov/burnwise/ |title=Burn Wise |publisher=United States Environmental Protection Agency |access-date=27 July 2012 |date=8 May 2013 |archive-date=19 March 2021 |archive-url=https://web.archive.org/web/20210319140434/https://www.epa.gov/burnwise |url-status=live }} [178] => [179] => [[Charcoal]] can be made by slow [[pyrolysis]] of wood by heating it in the absence of air in a [[kiln]]. The carefully stacked branches, often oak, are burned with a very limited amount of air. The process of converting them into charcoal takes about fifteen hours. Charcoal is used as a fuel in [[barbecue]]s and by [[blacksmith]]s and has many industrial and other uses.{{cite web |url=http://www.woodlands.co.uk/blog/practical-guides/how-do-you-make-charcoal/ |title=How do you make charcoal? |work=Woodlands.co.uk |publisher=Woodland Investment Management |access-date=27 July 2012 |archive-date=4 June 2012 |archive-url=https://web.archive.org/web/20120604175105/http://www.woodlands.co.uk/blog/practical-guides/how-do-you-make-charcoal/ |url-status=live }} [180] => [181] => ===Timber=== [182] => {{main|Wood|Timber}} [183] => [[File:Timberwork2.JPG|thumb|upright=1.2|left|Roof trusses made from softwood]] [184] => [185] => Timber, "trees that are grown in order to produce wood"{{cite web|title = timber {{!}} trees that are grown in order to produce wood|url = http://www.merriam-webster.com/dictionary/timber|website = www.merriam-webster.com|access-date = 3 September 2015|archive-date = 19 September 2015|archive-url = https://web.archive.org/web/20150919081941/http://www.merriam-webster.com/dictionary/timber|url-status = live}} is cut into lumber (sawn wood) for use in construction. Wood has been an important, easily available material for construction since humans started building shelters. [[Engineered wood]] products are available which bind the particles, fibres or [[Wood veneer|veneers]] of wood together with adhesives to form [[composite material]]s. Plastics have taken over from wood for some traditional uses.{{cite web |url=http://www.fao.org/docrep/004/Y3609E/Y3609E00.HTM |title=Environmental and energy balances of wood products and substitutes |last1=Scharai-Rad |first1=Mohammad |author2=Welling, Johannes |year=2002 |publisher=Food and Agriculture Organization of the United Nations |access-date=30 July 2012 |archive-date=9 November 2012 |archive-url=https://web.archive.org/web/20121109163747/http://www.fao.org/docrep/004/y3609e/y3609e00.htm |url-status=live }} [186] => [187] => Wood is used in the construction of buildings, bridges, trackways, piles, poles for power lines, masts for boats, pit props, railway sleepers, fencing, hurdles, shuttering for concrete, pipes, scaffolding and pallets. In housebuilding it is used in joinery, for making joists, roof trusses, roofing shingles, thatching, staircases, doors, window frames, floor boards, parquet flooring, panelling and cladding.{{cite web |url=http://www.appalachianwood.org/utilization.htm |title=Wood utilization |publisher=Appalachian Hardwood Manufacturers |access-date=27 July 2012 |archive-date=28 July 2012 |archive-url=https://web.archive.org/web/20120728010824/http://www.appalachianwood.org/utilization.htm |url-status=live }} [188] => [189] => [[File:Claude Monet, Weeping Willow.JPG|thumb|upright|Trees in art: ''[[Weeping Willow (painting)|Weeping Willow]]'', [[Claude Monet]], 1918]] [190] => [191] => Wood is used to construct carts, farm implements, boats, dugout canoes and in shipbuilding. It is used for making furniture, tool handles, boxes, ladders, musical instruments, bows, weapons, matches, clothes pegs, brooms, shoes, baskets, turnery, carving, toys, pencils, rollers, cogs, wooden screws, barrels, coffins, skittles, veneers, artificial limbs, oars, skis, wooden spoons, sports equipment and wooden balls. [192] => [193] => Wood is pulped for paper and used in the manufacture of cardboard and made into engineered wood products for use in construction such as [[Medium-density fibreboard|fibreboard]], [[hardboard]], [[Particle board|chipboard]] and [[plywood]]. The wood of conifers is known as [[softwood]] while that of broad-leaved trees is [[hardwood]].{{cite web |url=http://www.dnr.state.md.us/forests/gloss.html |archive-url=https://web.archive.org/web/20120712173543/http://www.dnr.state.md.us/forests/gloss.html |archive-date=12 July 2012 |title=Glossary of Forestry Terms |last=Pywell |first=Nancy |date=7 October 2003 |access-date=30 July 2012 |url-status=dead }} [194] => [195] => ===Art=== [196] => [197] => Besides inspiring artists down the centuries, trees have been used to create art. Living trees have been used in [[bonsai]] and in [[tree shaping]], and both living and dead specimens have been sculpted into sometimes fantastic shapes.{{cite magazine |url=http://mentalfloss.com/article/30098/10-artists-who-work-trees |title=10 Artists Who Work in Trees |author=Cellania, Miss |date=28 February 2012 |magazine=Mental Floss |access-date=20 September 2014 |archive-date=3 August 2014 |archive-url=https://web.archive.org/web/20140803191336/http://mentalfloss.com/article/30098/10-artists-who-work-trees |url-status=live }} [198] => [199] => ====Bonsai==== [200] => [[File:Dwarf Japanese Juniper, 1975-2007.jpg|thumb|upright|Informal upright style of [[bonsai]] on a [[juniper]] tree]] [201] => {{main|Bonsai}} [202] => [203] => {{Nihongo |Bonsai | 盆栽 | | lit. "Tray planting"}}{{cite book | last=Gustafson |first=Herbert L. | title=Miniature Bonsai | publisher=Sterling Publishing Company, Inc. | year=1995 | isbn=0-8069-0982-X | page=[https://archive.org/details/miniaturebonsai00gust/page/9 9] | url-access=registration | url=https://archive.org/details/miniaturebonsai00gust/page/9 }} is the practice of [[Hòn Non Bộ|''hòn non bộ'']] originated in China and spread to Japan more than a thousand years ago, there are similar practices in other cultures like the living miniature landscapes of Vietnam ''hòn non bộ''. The word ''bonsai'' is often used in English as an [[umbrella term]] for all miniature trees in containers or pots.{{cite book |first=David |last=Squire |title=The Bonsai Specialist |url=https://books.google.com/books?id=7IrFEu13suIC&pg=PA3 |year=2004 |publisher=New Holland Publishers |isbn=978-1-84330-543-9 |page=3 |access-date=28 February 2016 |archive-date=4 March 2017 |archive-url=https://web.archive.org/web/20170304193243/https://books.google.com/books?id=7IrFEu13suIC&pg=PA3 |url-status=live }} [204] => [205] => The purposes of bonsai are primarily contemplation (for the viewer) and the pleasant exercise of effort and ingenuity (for the grower).{{cite book |last=Chan |first=Peter |title=Bonsai Masterclass |publisher=Sterling Publishing Co., Inc. |year=1987 |isbn=978-0-8069-6763-9 |ref=bonsai_masterclass_peter_chan}} Bonsai practice focuses on long-term cultivation and shaping of one or more small trees growing in a container, beginning with a cutting, seedling, or small tree of a species suitable for bonsai development. Bonsai can be created from nearly any [[perennial]] woody-stemmed tree or shrub species{{cite book |last=Owen |first=Gordon |title=The Bonsai Identifier |publisher=Quintet Publishing Ltd. |year=1990 |isbn=978-0-88665-833-5 |page=[https://archive.org/details/bonsaiidentifier0000owen/page/11 11] |url=https://archive.org/details/bonsaiidentifier0000owen/page/11 }} that produces true branches and can be cultivated to remain small through pot confinement with crown and root pruning. Some [[List of species used in bonsai|species]] are popular as bonsai material because they have characteristics, such as small leaves or needles, that make them appropriate for the compact visual scope of bonsai and a miniature deciduous forest can even be created using such species as [[Japanese maple]], [[Zelkova serrata|Japanese zelkova]] or [[hornbeam]].{{cite book |first=David |last=Squire |title=The Bonsai Specialist |url=https://books.google.com/books?id=7IrFEu13suIC&pg=PA66 |year=2004 |publisher=New Holland Publishers |isbn=978-1-84330-543-9 |page=66 |access-date=28 February 2016 |archive-date=4 March 2017 |archive-url=https://web.archive.org/web/20170304135627/https://books.google.com/books?id=7IrFEu13suIC&pg=PA66 |url-status=live }} [206] => [207] => ====Tree shaping==== [208] => {{main|Tree shaping}} [209] => [[File:Person-tree.jpg|thumb|left|''People trees'', by Pooktre]] [210] => [211] => Tree shaping is the practice of changing living trees and other woody plants into man made shapes for art and useful structures. There are a few different methods{{Cite journal |first=Mörður |last=Gunnarsson |title=Living Furniture |journal=Cottage and Garden |pages=28–29 |year=2012 }} of shaping a tree. There is a gradual method and there is an instant method. The gradual method slowly guides the growing tip along predetermined pathways over time whereas the instant method bends and weaves saplings {{convert|2|to|3|m|ft|abbr=on}} long into a shape that becomes more rigid as they thicken up.{{cite book |author=Dwell, LLC |title=Dwell |url=https://books.google.com/books?id=f8YDAAAAMBAJ&pg=PA96 |date=February 2007 |publisher=Dwell, LLC |page=96 |issn=1530-5309 |access-date=28 February 2016 |archive-date=4 March 2017 |archive-url=https://web.archive.org/web/20170304135950/https://books.google.com/books?id=f8YDAAAAMBAJ&pg=PA96 |url-status=live }} Most artists use grafting of living trunks, branches, and roots, for art or functional structures and there are plans to grow "living houses" with the branches of trees knitting together to give a solid, weatherproof exterior combined with an interior application of straw and clay to provide a [[stucco]]-like inner surface. [212] => [213] => Tree shaping has been practised for at least several hundred years, the oldest known examples being the [[living root bridges]] built and maintained by the [[Khasi people|Khasi]] people of [[Meghalaya]], India using the roots of the [[Ficus elastica|rubber tree]] (''Ficus elastica'').{{cite web |url=http://www.picturesw.com/2012/08/the-natural-root-bridges-of-cherrapunji.html |title=The natural root bridges of Cherrapunji, India |date=7 August 2012 |publisher=Pictures World |access-date=17 September 2014 |archive-date=24 September 2014 |archive-url=https://web.archive.org/web/20140924180958/http://www.picturesw.com/2012/08/the-natural-root-bridges-of-cherrapunji.html |url-status=live }}{{cite web |url=http://www.treehugger.com/sustainable-product-design/living-bridges-in-india-have-grown-for-500-years-pics.html |title=Living Bridges in India Have Grown for 500 Years |last=Merchant |first=Brian |date=28 September 2010 |work=Treehugger |access-date=17 September 2014 |archive-date=23 October 2014 |archive-url=https://web.archive.org/web/20141023050359/http://www.treehugger.com/sustainable-product-design/living-bridges-in-india-have-grown-for-500-years-pics.html |url-status=live }} [214] => [215] => ===Bark=== [216] => [[File:CorkOakStripped.jpg|thumb|upright|Recently stripped cork oak (''[[Quercus suber]]'')]] [217] => {{further|Bark (botany)}} [218] => [219] => [[Cork (material)|Cork]] is produced from the thick bark of the cork oak (''[[Quercus suber]]''). It is harvested from the living trees about once every ten years in an environmentally sustainable industry.{{cite web |url=http://www.azom.com/news.aspx?newsID=4951 |title=Cork Flooring is Environmentally Sustainable |date=27 February 2006 |publisher=AZoM.com |access-date=26 July 2012 |archive-date=7 November 2012 |archive-url=https://web.archive.org/web/20121107104856/http://www.azom.com/news.aspx?newsID=4951 |url-status=live }} More than half the world's cork comes from Portugal and is largely used to make stoppers for wine bottles.{{cite web |url=http://people.uwec.edu/ivogeler/Travel/Portugal/cork-article2.htm |title=The cork industry in Portugal |author1=Calheiros e Meneses |author2=J. L. |publisher=University of Wisconsin |access-date=26 July 2012 |archive-date=14 September 2014 |archive-url=https://web.archive.org/web/20140914040935/http://people.uwec.edu/ivogeler/Travel/Portugal/cork-article2.htm |url-status=live }} Other uses include floor tiles, bulletin boards, balls, footwear, cigarette tips, packaging, insulation and joints in woodwind instruments. [220] => [221] => The bark of other varieties of oak has traditionally been used in Europe for the [[Tanning (leather)|tanning]] of hides though bark from other species of tree has been used elsewhere. The active ingredient, [[tannin]], is extracted and after various preliminary treatments, the skins are immersed in a series of vats containing solutions in increasing concentrations. The tannin causes the hide to become supple, less affected by water and more resistant to bacterial attack.{{cite web |title=3. Tanneries, Description of the Tanning Process |access-date=26 July 2012 |publisher=Food and Agriculture Organization of the United Nations |url=http://www.fao.org/WAIRDOCS/LEAD/X6114E/x6114e05.htm#b1-3.1.%20Description%20of%20the%20tanningprocess |archive-date=22 August 2011 |archive-url=https://web.archive.org/web/20110822080512/http://www.fao.org/WAIRDOCS/LEAD/X6114E/x6114e05.htm#b1-3.1.%20Description%20of%20the%20tanningprocess |url-status=live }} [222] => [223] => At least 120 drugs come from [[medicinal plant|plant sources]], many of them from the bark of trees.{{cite web |url=http://rainforest-database.com/plants/plantdrugs.htm |title=Plant Based Drugs and Medicines |author=Taylor, Leslie |date=13 October 2000 |work=The Healing Power of Rainforest Herbs |access-date=27 July 2012 |archive-date=29 June 2012 |archive-url=https://web.archive.org/web/20120629144821/http://rainforest-database.com/plants/plantdrugs.htm |url-status=live }} [[Quinine]] originates from the cinchona tree (''[[Cinchona]]'') and was for a long time the remedy of choice for the treatment of [[malaria]].{{cite web |title=Guidelines for the treatment of malaria |publisher=World Health Organization |url=http://apps.who.int/iris/bitstream/10665/162441/1/9789241549127_eng.pdf?ua=1&ua=1 |year=2006 |access-date=26 July 2012 |archive-date=13 October 2015 |archive-url=https://web.archive.org/web/20151013193459/http://apps.who.int/iris/bitstream/10665/162441/1/9789241549127_eng.pdf?ua=1&ua=1 |url-status=live }} [[Aspirin]] was synthesised to replace the [[sodium salicylate]] derived from the bark of willow trees (''[[Salix]]'') which had unpleasant side effects.{{Cite journal |last1=Sneader |first1=W. |title=The discovery of aspirin: A reappraisal |journal=BMJ (Clinical Research Ed.) |volume=321 |issue=7276 |pages=1591–1594 |year=2000 |pmid=11124191 |pmc=1119266 |doi=10.1136/bmj.321.7276.1591}} The anti-cancer drug [[Paclitaxel]] is derived from taxol, a substance found in the bark of the Pacific yew (''[[Taxus brevifolia]]'').{{cite book |last1=Goodman |first1=Jordan |last2=Walsh |first2=Vivien |title=The Story of Taxol: Nature and Politics in the Pursuit of an Anti-Cancer Drug |publisher=Cambridge University Press |year=2001 |isbn=978-0-521-56123-5 |page=[https://archive.org/details/storyoftaxolnatu00jord/page/17 17] |url=https://archive.org/details/storyoftaxolnatu00jord/page/17 }} Other tree based drugs come from the paw-paw (''[[Carica papaya]]''), the cassia ([[Cassia (genus)|''Cassia'' spp.]]), the cocoa tree (''Theobroma cacao''), the tree of life (''[[Camptotheca acuminata]]'') and the downy birch (''[[Betula pubescens]]''). [224] => [225] => The papery bark of the white birch tree (''[[Betula papyrifera]]'') was used extensively by [[Indigenous peoples of the Americas|Native Americans]]. [[Wigwam]]s were covered by it and [[canoe]]s were constructed from it. Other uses included food containers, hunting and fishing equipment, musical instruments, toys and sledges.{{cite web |url=http://www.nativetech.org/brchbark/brchbark.htm |title=Uses for birch bark |author=Prindle, Tara |year=1994 |publisher=NativeTech: Native American Technology and Art |access-date=27 July 2012 |archive-date=18 September 2012 |archive-url=https://web.archive.org/web/20120918040348/http://www.nativetech.org/brchbark/brchbark.htm |url-status=live }} Nowadays, bark chips, a by-product of the timber industry, are used as a mulch and as a growing medium for epiphytic plants that need a soil-free compost.{{cite web |url=http://www.orchid-growing-secrets.com/choosing-the-right-potting-media-for-your-orchid/ |archive-url=https://web.archive.org/web/20121115211019/http://www.orchid-growing-secrets.com/choosing-the-right-potting-media-for-your-orchid/ |archive-date=15 November 2012 |title=Choosing the right potting media for your orchid |author=Johnson, Aidan |date=25 January 2011 |work=Orchid growing secrets |access-date=27 July 2012 |url-status=dead }} [226] => [227] => [[File:Fontaine-l'Eveque JPG01c.jpg|thumb|left|[[Avenue (landscape)|Alleé]] of [[Platanus × acerifolia|London plane trees (''Platanus'' × ''acerifolia'')]] in garden]] [228] => [229] => ===Ornamental trees=== [230] => {{main|Ornamental trees}} [231] => Trees create a visual impact in the same way as do other landscape features and give a sense of maturity and permanence to park and garden. They are grown for the beauty of their forms, their foliage, flowers, fruit and bark and their siting is of major importance in creating a landscape. They can be grouped informally, often surrounded by plantings of bulbs, laid out in stately avenues or used as specimen trees. As living things, their appearance changes with the season and from year to year.{{cite book |title=The Royal Horticultural Society Encyclopedia of Gardening |editor-last=Brickell |editor-first=Christopher |year=1992 |publisher=Dorling Kindersley |chapter=Ornamental trees |isbn=978-0-86318-979-1 |pages=32–33}} [232] => [233] => Trees are often planted in town environments where they are known as street trees or amenity trees. They can provide shade and cooling through [[evapotranspiration]], absorb greenhouse gases and pollutants, intercept rainfall, and reduce the risk of flooding. Scientific studies show that street trees help cities be more sustainable, and improve the physical and mental wellbeing of the citizens.{{Cite journal |last1=Turner-Skoff|first1=J. |last2=Cavender|first2=N. |title=The Benefits of Trees for Livable and Sustainable Communities |journal=Plants, People, Planet |volume=1 |issue=4 |pages=323–335 |year=2019 |doi=10.1002/ppp3.39|doi-access=free }} It has been shown that they are beneficial to humans in creating a sense of well-being and reducing stress. Many towns have initiated tree-planting programmes.{{cite web |url=http://www.forestry.gov.uk/fr/urgc-7EKEC8 |title=Street trees |work=Greenspace initiative |publisher=Forestry Commission |access-date=20 September 2014 |archive-date=4 March 2016 |archive-url=https://web.archive.org/web/20160304110933/http://www.forestry.gov.uk/fr/urgc-7EKEC8 |url-status=live }} In London for example, there is an initiative to plant 20,000 new street trees and to have an increase in tree cover of 5% by 2025, equivalent to one tree for every resident.{{cite web |url=https://www.london.gov.uk/WHAT-WE-DO/environment/parks-green-spaces-and-biodiversity/releaf-partnership |title=The RE:LEAF Partnership|work=Greening London |publisher=Mayor of London |access-date=20 September 2014 |date=10 August 2015 |archive-date=24 April 2016 |archive-url=https://web.archive.org/web/20160424163422/https://www.london.gov.uk/what-we-do/environment/parks-green-spaces-and-biodiversity/releaf-partnership |url-status=live }} [234] => [235] => ===Other uses=== [236] => [[File:Sri Lanka-Rubber plantation (5).JPG|thumb|upright|[[Latex]] collecting from a [[Hevea brasiliensis|rubber tree (''Hevea brasiliensis'')]]]] [237] => {{further|Resin|Latex|Camphor}} [238] => [239] => Latex is a sticky defensive secretion that protects plants against [[herbivore]]s. Many trees produce it when injured but the main source of the latex used to make [[natural rubber]] is the Pará rubber tree (''Hevea brasiliensis''). Originally used to create bouncy balls and for the waterproofing of cloth, natural rubber is now mainly used in tyres for which synthetic materials have proved less durable.{{cite web |url=http://www.azom.com/article.aspx?ArticleID=2101 |title=Natural rubber: History and Developments in the Natural Rubber Industry |author=Baker, C |year=1997 |work=Materials World |publisher=AZoM.com |access-date=26 July 2012 |archive-date=28 July 2012 |archive-url=https://web.archive.org/web/20120728170522/http://www.azom.com/article.aspx?ArticleID=2101 |url-status=live }} The latex exuded by the balatá tree (''[[Manilkara bidentata]]'') is used to make [[golf ball]]s and is similar to [[gutta-percha]], made from the latex of the "getah perca" tree ''[[Palaquium]]''. This is also used as an insulator, particularly of undersea cables, and in dentistry, walking sticks and gun butts. It has now largely been replaced by synthetic materials.{{cite web |url=http://www.atlantic-cable.com/Article/GuttaPercha/ |title=The Gutta Percha Company |author=Burns, Bill |date=15 February 2010 |work=History of the Atlantic Cable and Undersea Communications |access-date=26 July 2012 |archive-date=23 April 2018 |archive-url=https://web.archive.org/web/20180423170435/http://atlantic-cable.com/Article/GuttaPercha/ |url-status=live }} [240] => [241] => Resin is another plant exudate that may have a defensive purpose. It is a viscous liquid composed mainly of volatile [[terpene]]s and is produced mostly by coniferous trees. It is used in varnishes, for making small castings and in [[ten-pin bowling]] balls. When heated, the terpenes are driven off and the remaining product is called "rosin" and is used by stringed instrumentalists on their [[Bow (music)|bows]]. Some resins contain [[essential oil]]s and are used in [[incense]] and [[aromatherapy]]. Fossilised resin is known as amber and was mostly formed in the Cretaceous (145 to 66 million years ago) or more recently. The resin that oozed out of trees sometimes trapped insects or spiders and these are still visible in the interior of the amber.{{cite web |url=http://gurukul.ucc.american.edu/ted/amber.htm |title=Amber Trade and the Environment in the Kaliningrad Oblast |author=Jacobson, Douglas |year=1997 |work=The Mandala Projects |access-date=26 July 2012 |url-status=dead |archive-url=https://web.archive.org/web/20120706182814/http://gurukul.ucc.american.edu/ted/amber.htm |archive-date=6 July 2012 }} [242] => [243] => The camphor tree (''[[Cinnamomum camphora]]'') produces an essential oil and the eucalyptus tree (''[[Eucalyptus globulus]]'') is the main source of [[eucalyptus oil]] which is used in medicine, as a fragrance and in industry.{{cite web |url=http://www.fao.org/docrep/v5350e/v5350e07.htm |publisher=Food and Agriculture Organization of the United Nations |title=Chapter 5: Eucalyptus oil |work=Flavours and fragrances of plant origin |access-date=19 March 2015 |archive-date=2 May 2012 |archive-url=https://web.archive.org/web/20120502162220/http://www.fao.org/docrep/V5350E/V5350e07.htm |url-status=live }} [244] => [245] => ==Threats== [246] => [247] => ===Individual trees=== [248] => Dead trees pose a safety risk, especially during high winds and severe storms, and removing dead trees involves a financial burden, whereas the presence of healthy trees can clean the air, increase property values, and reduce the temperature of the built environment and thereby reduce building cooling costs. During times of drought, trees can fall into [[moisture stress|water stress]], which may cause a tree to become more susceptible to disease and insect problems, and ultimately may lead to a tree's death. Irrigating trees during dry periods can reduce the risk of water stress and death.{{cite web |url=http://texasforestservice.tamu.edu/AftertheStorm/Drought/ |title=Texas drought |work=Texas A&M Forest Service |publisher=Texas A&M University System |access-date=10 September 2012 |archive-date=7 September 2015 |archive-url=https://web.archive.org/web/20150907032456/http://texasforestservice.tamu.edu/AftertheStorm/Drought/ |url-status=live }} [249] => [250] => ===Conservation=== [251] => [252] => About a third of all tree species, some twenty thousand, are included in the [[IUCN]] Red List of Threatened Species. Of those, over eight thousand are globally threatened, including at least 1400 which are classed as "critically endangered".{{cite book |title=The State of the World's Forests 2020. Forests, biodiversity and people – In brief |publisher=FAO & UNEP |year=2020 |doi=10.4060/ca8985en |isbn=978-92-5-132707-4 |s2cid=241416114 |url=https://doi.org/10.4060/ca8985en |access-date=2 December 2020 |archive-date=20 May 2021 |archive-url=https://web.archive.org/web/20210520193013/http://www.fao.org/documents/card/en/c/ca8985en |url-status=live }} [253] => [254] => ==Mythology== [255] => {{main|Trees in mythology}} [256] => [[File:yggdrasil.jpg|thumb|upright|left|[[Yggdrasil]], the World Ash of [[Norse mythology]]]] [257] => [258] => Trees have been venerated since time immemorial. To the ancient [[Celtic tree worship|Celts]], certain trees, especially the [[oak]], [[Fraxinus|ash]] and [[Crataegus|thorn]], held special significance{{cite web |url=http://wicca.com/celtic/celtic/sactrees.htm |title=Sacred Celtic Trees and Woods |editor=Collins |work=The Celtic Connection |access-date=29 July 2012 |archive-date=11 August 2012 |archive-url=https://web.archive.org/web/20120811104708/http://wicca.com/celtic/celtic/sactrees.htm |url-status=live }} as providing fuel, building materials, ornamental objects and weaponry. Other cultures have similarly revered trees, often linking the lives and fortunes of individuals to them or using them as oracles. In [[Greek mythology]], [[dryad]]s were believed to be shy nymphs who inhabited trees. [259] => [260] => The Oubangui people of west Africa plant a tree when a child is born. As the tree flourishes, so does the child but if the tree fails to thrive, the health of the child is considered at risk. When it flowers it is time for marriage. Gifts are left at the tree periodically and when the individual dies, their spirit is believed to live on in the tree.{{cite web |url=http://www.fao.org/docrep/t9450e/t9450e06.htm |title=The cultural and symbolic importance of forest resources |publisher=Food and Agriculture Organization of the United Nations |access-date=29 July 2012 |archive-date=1 May 2013 |archive-url=https://web.archive.org/web/20130501233100/http://www.fao.org/docrep/t9450e/t9450e06.htm |url-status=live }} [261] => [262] => Trees have their roots in the ground and their trunk and branches extended towards the sky. This concept is found in many of the world's religions as a tree which links the underworld and the earth and holds up the heavens. In [[Norse mythology]], [[Yggdrasil]] is a central cosmic tree whose roots and branches extend to various worlds. Various creatures live on it.Lindow, John (2001). ''Norse Mythology: A Guide to the Gods, Heroes, Rituals, and Beliefs'', pp. 319–322. Oxford University Press. {{ISBN|0-19-515382-0}} In India, [[Kalpavriksha]] is a wish-fulfilling tree, one of the nine jewels that emerged from the primitive ocean. Icons are placed beneath it to be worshipped, tree nymphs inhabit the branches and it grants favours to the devout who tie threads round the trunk.{{cite news |title=The sacred tree |author=Dehejia, Harsha V. |url=http://timesofindia.indiatimes.com/life-style/The-sacred-tree/articleshow/10903458.cms |newspaper=The Times of India |date=21 December 2011 |access-date=29 July 2012 |archive-date=23 May 2014 |archive-url=https://web.archive.org/web/20140523042536/http://timesofindia.indiatimes.com/life-style/The-sacred-tree/articleshow/10903458.cms |url-status=live }} Democracy started in North America when the [[Great Peacemaker]] formed the [[Iroquois|Iroquois Confederacy]], inspiring the warriors of the original five American nations to bury their weapons under the [[Tree of Peace]], an eastern white pine (''[[Pinus strobus]]'').{{cite web |url=http://cae.ls.wisc.edu/tree-of-peace.htm |archive-url=https://web.archive.org/web/20140922020705/http://cae.ls.wisc.edu/tree-of-peace.htm |archive-date=22 September 2014 |title=The Tree of Peace |work=American Indian Student Academic Services |publisher=University of Wisconsin |access-date=29 July 2012 |url-status=dead }} In the creation story in the Bible, the [[Tree of life (biblical)|tree of life and the knowledge of good and evil]] was planted by God in the [[Garden of Eden]].{{cite web |url=http://www.cs.williams.edu/~lindsey/myths/myths_15.html |title=Hebrew/Christian Creation Myth: Genesis 2, v.8 |work=The Bible |publisher=New International Version |access-date=29 July 2012 |archive-date=18 June 2012 |archive-url=https://web.archive.org/web/20120618220229/http://www.cs.williams.edu/~lindsey/myths/myths_15.html |url-status=live }} [263] => [264] => [[Sacred grove]]s exist in China, India, Africa and elsewhere. They are places where the deities live and where all the living things are either sacred or are companions of the gods. Folklore lays down the supernatural penalties that will result if desecration takes place for example by the felling of trees. Because of their protected status, sacred groves may be the only relicts of ancient forest and have a biodiversity much greater than the surrounding area.{{cite journal |author=Laird, Sarah |year=1999 |title=Trees, forests and sacred groves |journal=The Overstory |volume=93 |url=http://www.agroforestry.net/overstory-back-issues/74-overstory-195-trees-forests-and-sacred-groves |access-date=22 October 2016 |archive-date=23 October 2016 |archive-url=https://web.archive.org/web/20161023052147/http://www.agroforestry.net/overstory-back-issues/74-overstory-195-trees-forests-and-sacred-groves |url-status=live }} Some Ancient Indian [[tree deity|tree deities]], such as Puliyidaivalaiyamman, the [[Tamil People|Tamil]] deity of the [[tamarind|tamarind tree]], or Kadambariyamman, associated with the [[cadamba tree]], were seen as manifestations of a goddess who offers her blessings by giving fruits in abundance.{{cite web |title=Cosmic Tree |url=http://www.khandro.net/nature_trees.htm |publisher=Khandro.net |access-date=5 June 2016 |archive-date=23 January 2016 |archive-url=https://web.archive.org/web/20160123204004/http://www.khandro.net/nature_trees.htm |url-status=live }} [265] => [266] => ==Superlative trees== [267] => [[File:General Sherman tree looking up.jpg|thumb|upright|The [[General Sherman Tree]], thought to be the world's largest by volume]] [268] => [269] => {{main | List of superlative trees}} [270] => [271] => Trees have a theoretical maximum height of {{convert|130|m|ft|abbr=on}},{{Cite journal |last1=Koch |first1=George W. |last2=Sillett |first2=Stephen C. |last3=Jennings |first3=Gregory M. |last4=Davis |first4=Stephen D. |date=22 April 2004 |title=The limits to tree height |journal=Nature |language=en |volume=428 |issue=6985 |pages=851–854 |doi=10.1038/nature02417 |pmid=15103376 |bibcode=2004Natur.428..851K |s2cid=11846291 }} but the tallest known specimen on earth is believed to be a coast redwood (''[[Sequoia sempervirens]]'') at [[Redwood National Park]], California. It has been named [[Hyperion (tree)|Hyperion]] and is {{convert|115.85|m|ft|abbr=on}} tall.{{cite web |url=http://www.conifers.org/cu/Sequoia.php |title=Sequoia sempervirens |work=The Gymnosperm Database |editor=Earle, Christopher J. |date=2017 |access-date=15 September 2017 |archive-date=1 April 2016 |archive-url=https://web.archive.org/web/20160401041103/http://www.conifers.org/cu/Sequoia.php |url-status=live }} In 2006, it was reported to be {{convert|379.1|ft|m|abbr=on}} tall.{{cite news |title=Humboldt County: World's tallest tree, a redwood, confirmed |author=Martin, Glen |url=http://www.sfgate.com/bayarea/article/HUMBOLDT-COUNTY-World-s-tallest-tree-a-2550557.php |newspaper=San Francisco Chronicle |date=26 September 2006 |access-date=1 July 2012 |archive-date=9 July 2012 |archive-url=https://web.archive.org/web/20120709180523/http://www.sfgate.com/bayarea/article/HUMBOLDT-COUNTY-World-s-tallest-tree-a-2550557.php |url-status=live }} The tallest known broad-leaved tree is a mountain ash (''[[Eucalyptus regnans]]'') growing in Tasmania with a height of {{convert|99.8|m|ft|abbr=on}}.{{cite web |url=http://www.gianttrees.com.au/index.php/meet-the-giants/tassies-tallest-trees |archive-url=https://web.archive.org/web/20140210163226/http://www.gianttrees.com.au/index.php/meet-the-giants/tassies-tallest-trees |archive-date=10 February 2014 |title=Tassies Tallest Trees |access-date=19 March 2015 |publisher=Tasmanian Giant Trees Consultative Committee |quote=Height (m): 99.8; Species: ''E. regnans''; Tree identification: TT443; Name: Centurion; Location: south of Hobart |url-status=dead }} [272] => [273] => The largest tree by volume is believed to be a giant sequoia (''[[Sequoiadendron giganteum]]'') known as the [[General Sherman Tree]] in the [[Sequoia National Park]] in [[Tulare County, California]]. Only the trunk is used in the calculation and the volume is estimated to be {{convert|1487|m3|cuft|abbr=on}}.{{cite web |title=Sequoiadendron giganteum |url=http://www.conifers.org/cu/Sequoiadendron.php |editor=Earle, Christopher J. |date=2017 |work=The Gymnosperm Database |access-date=15 September 2017 |archive-date=25 March 2017 |archive-url=https://web.archive.org/web/20170325012913/http://conifers.org/cu/Sequoiadendron.php |url-status=live }} [274] => [275] => The oldest living tree with a verified age is also in California. It is a Great Basin bristlecone pine (''[[Pinus longaeva]]'') growing in the [[White Mountains (California)|White Mountains]]. It has been dated by drilling a core sample and counting the annual rings. It is estimated to currently be {{formatnum:{{Age|-3055|8|31}}}} years old.{{efn|That bristlecone pine is unnamed, its location secret. The previous record holder was named Methuselah, with an age of 4,789 years measured in 1957.}}{{cite web |url=http://www.conifers.org/pi/Pinus_longaeva.php |title=Pinus longaeva |editor=Earle, Christopher J. |date=2017 |work=The Gymnosperm Database |access-date=15 September 2017 |archive-date=17 May 2019 |archive-url=https://web.archive.org/web/20190517015108/https://www.conifers.org/pi/Pinus_longaeva.php |url-status=live }} [276] => [277] => A little farther south, at [[Santa Maria del Tule]], [[Oaxaca]], Mexico, is the tree with the broadest trunk. It is a Montezuma cypress (''[[Taxodium mucronatum]]'') known as [[Árbol del Tule]] and its diameter at breast height is {{convert|11.62|m|ft|abbr=on}} giving it a girth of {{convert|36.2|m|ft|abbr=on}}. The tree's trunk is far from round and the exact dimensions may be misleading as the circumference includes much empty space between the large buttress roots.{{cite web |url=http://www.conifers.org/cu/Taxodium_mucronatum.php |title=Taxodium mucronatum |editor=Earle, Christopher J. |date=2017 |work=The Gymnosperm Database |access-date=15 September 2017 |archive-date=10 October 2017 |archive-url=https://web.archive.org/web/20171010032604/http://conifers.org/cu/Taxodium_mucronatum.php |url-status=live }} [278] => [279] => ==See also== [280] => {{columns-list | colwidth=20em | [281] => * [[Agroforestry]] [282] => * [[Arboretum]] [283] => * [[da Vinci branching rule]] [284] => * [[Dendrology]] [285] => * [[Dendrometry]] [286] => * [[Exploding tree]] [287] => * [[Five Trees]] [288] => * [[Forest restoration]] [289] => * [[Fruit tree]] [290] => * [[Great Green Wall (Africa)]] [291] => * [[i-Tree]] [292] => * [[Lists of trees|List of lists of trees]] [293] => * [[Million Tree Initiative]] [294] => * [[Multipurpose tree]] – a tree grown and managed for more than one output [295] => * [[Reforestation]] [296] => * [[Tree climbing]] [297] => * [[Tree credits]] [298] => * [[Tree house]] [299] => * [[Tree planting bar]] [300] => * [[Tree planting]] [301] => * [[Trillion Tree Campaign]] [302] => * [[Urban forest]] [303] => * [[Urban forestry]] [304] => * [[Urban reforestation]] [305] => }} [306] => [307] => ==Notes== [308] => {{notelist}} [309] => [310] => ==References== [311] => {{reflist}} [312] => [313] => {{commons|Trees}} [314] => {{Portal bar|Trees}} [315] => [316] => {{botany}} [317] => {{forestry}} [318] => [319] => {{Authority control}} [320] => [321] => [[Category:Trees| ]] [322] => [[Category:Forest ecology]] [323] => [[Category:Plant morphology]] [324] => [[Category:Plant life-forms]] [325] => [[Category:Plants by habit]] [] => )
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Tree

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, only plants that are usable as lumber, only plants above a specified height, or only perennial species.

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In some usages, the definition of a tree may be narrower, including only woody plants, only plants that are usable as lumber, only plants above a specified height, or only perennial species. At its broadest, a tree is any plant with the general form of an elongated stem, or trunk, which supports the photosynthetic leaves or branches at some distance above the ground. Trees are also typically defined by height, with smaller plants being called shrubs, and their height limit being different in different parts of the world. Trees are an important component of the natural landscape due to their prevention of erosion and involvement in the water cycle. They also play a crucial role in producing oxygen and reducing carbon dioxide in the atmosphere, as well as providing shelter and food for many species of animals. Additionally, trees hold cultural significance in various societies and have been used for religious, spiritual, and practical purposes throughout history. The Wikipedia page on trees provides comprehensive information about different types of trees, their anatomy, classification, growth, reproduction, ecological interactions, and significance. It also explores the history of trees, including their use in human societies, forestry practices, and conservation efforts. The page covers a wide range of topics related to trees, making it a valuable resource for anyone interested in botany, ecology, environmental science, or general knowledge about the natural world.

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