View source for Hevea brasiliensis

{{short description|Most common rubber tree}}
{{Redirect2|Rubber tree|para rubber|the ornamental plant also known as "rubber tree"|Ficus elastica{{!}}''Ficus elastica''|the New Zealand brand Para Rubber|Skellerup}}
{{speciesbox
|image =Hevea_brasiliensis_-_Köhler–s_Medizinal-Pflanzen-071.jpg
|genus = Hevea
|species = brasiliensis
|status = LC
|status_system = IUCN3.1
|status_ref =  <ref>{{cite journal |last1=Fabriani |first1=F. |last2=Hills |first2=R. |title=Hevea brasiliensis |journal=The IUCN Red List of Threatened Species |date=2020 |page=e.T62003521A62003529 |doi=10.2305/IUCN.UK.2020-2.RLTS.T62003521A62003529.en |url=https://dx.doi.org/10.2305/IUCN.UK.2020-2.RLTS.T62003521A62003529.en| access-date=28 October 2022}}</ref>
|authority = [[Johannes Müller Argoviensis|Müll.Arg.]]
|range_map = Distribution of Hevea sp.jpg
|range_map_caption = Range of the genus ''Hevea''.
}}

'''''Hevea brasiliensis''''', the '''Pará rubber tree''', '''''sharinga'' tree, seringueira''', or most commonly, '''rubber tree''' or '''rubber plant''', is a [[flowering plant]] belonging to the spurge family, [[Euphorbiaceae]], originally native to the [[Amazon basin]], but is now [[pantropical]] in distribution due to [[introduced species|introductions]]. It is the most economically important member of the genus ''[[Hevea]]'' because the milky [[latex]] extracted from the tree is the primary source of [[natural rubber]].

==Description==
[[Image:Koh Chang, Thailand, Rubber tree.jpg|thumb|right|Canopy and trunk, Thailand]]
''Hevea brasiliensis'' is a tall [[deciduous]] tree growing to a height of up to {{convert|43|m|ft|0|abbr=on}} in the wild. Cultivated trees are usually much smaller because drawing off the latex restricts their growth. The trunk is cylindrical and may have a swollen, bottle-shaped base. The bark is some shade of brown, and the inner bark oozes [[latex]] when damaged. The leaves have three [[Leaflet (botany)|leaflets]] and are spirally arranged. The [[inflorescence]]s include separate male and female flowers. The flowers are pungent, creamy-yellow and have no petals. The fruit is a capsule that contains three large seeds; it opens explosively when ripe.<ref>{{cite web |url=http://powo.science.kew.org/taxon/urn:lsid:ipni.org:names:349913-1 |title=''Hevea brasiliensis'' (Willd. ex A.Juss.) Müll.Arg. |work=[[Plants of the World online]]|publisher=[[Kew Science]]|access-date=31 March 2017}}</ref>

==Rubber tree plantation==
[[File:Hevea semillas2.jpg|thumb|150px|right|Seeds]]
[[File:Sprouting rubber tree seed.jpg|thumb|150px|right|A sprouting seed in a house backyard in [[Malaysia]]]]

In the wild the tree can reach a height of up to {{convert|43|m|ft}}. The white or yellow latex occurs in latex vessels in the [[Bark (botany)|bark]], mostly outside the [[phloem]]. These vessels spiral up the tree in a right-handed [[helix]] which forms an [[angle]] of about 30 degrees with the horizontal, and can grow as high as {{convert|15|m}}.<ref name=FAO/>

In plantations the trees are generally smaller for two reasons: 1) trees grow more slowly when they are tapped for latex, and 2) trees are generally cut down after only 30 years, because latex production declines as trees age, and they are no longer economically productive. The tree requires a [[Tropical climate|tropical]] or [[subtropical climate]] with a minimum of about {{Convert|1,200|mm|in|abbr=on|sp=us|sigfig=1}} per year of rainfall, and no frost.<ref name=eb/> If frost does occur, the results can be disastrous for production. One frost can cause the rubber from an entire plantation to become brittle and break once it has been refined.<ref>{{cite web |url=http://www.fao.org/docrep/006/AD221E/AD221E01.htm |title=The rubber tree |publisher=UN [[FAO]]|access-date=29 May 2017}}</ref>

===Latex tapping===
{{Main|Rubber  tapping}}
[[File:The face of rubber tree's trunk.jpg|thumb|right|150px|Trunk crosssection]]
[[File:Tapped rubber tree.jpg|thumb|right|150px|Latex being collected from an incised rubber tree and a bucket of collected latex]]
[[File:“Spiral tapping of Hevea Brasiliensis”.jpg|thumb|right|200px|"Spiral tapping of ''Hevea brasiliensis''." Photograph circa 1911, taken in Brazil.]]
The rubber tree takes between seven and ten years to deliver the first harvest.<ref>{{cite web |title= Natural rubber from dandelions  | url= https://phys.org/news/2015-06-natural-rubber-dandelions.html}}</ref>
Harvesters make incisions across the latex vessels, just deep enough to tap the vessels without harming the tree's growth, and the latex is collected in small buckets. This process is known as [[rubber tapping]]. Latex production is highly variable from tree to tree and across clone types.<ref name=FAO>{{cite web |url=http://www.fao.org/docrep/006/AD221E/AD221E06.htm |title=Rubber tapping |publisher=UN [[FAO]]|access-date=29 May 2017}}</ref>

===Wood harvesting===
{{Main|Rubberwood}}
As latex production declines with age, rubber trees are generally [[Felling|felled]] when they reach the age of 25 to 30 years. The earlier practice was to burn the trees, but in recent decades, the wood has been harvested for furniture making.<ref name=FAO/>

==History==
The South American rubber tree grew only in the [[Amazon rainforest]], and increasing demand and the discovery of the [[vulcanization]] procedure in 1839 led to the rubber boom in that region, enriching the cities of [[Belém do Pará|Belém]], [[Santarém, Pará|Santarém]], and [[Manaus]] in Brazil and [[Iquitos]], Peru, from 1840 to 1913. In Brazil, before the name was changed to 'Seringueira' the initial name of the plant was 'pará rubber tree', derived from the name of the province of [[State of Grão-Pará and Rio Negro|Grão-Pará]]. In Peru, the tree was called 'árbol del caucho', and the latex extracted from it was called 'caucho'. The tree was used to obtain rubber by the natives who inhabited its geographical distribution. The [[Olmec]] people of [[Mesoamerica]] extracted and produced similar forms of primitive rubber from analogous latex-producing trees such as ''[[Castilla elastica]]'' as early as 3,600 years ago. The rubber was used, among other things, to make the balls used in the [[Mesoamerican ballgame]].<ref>{{cite web |url=https://www.maya-archaeology.org/Mayan_anthropology_ethnography_archaeology_art_history_iconography_epigraphy_ethnobotany/rubber_hule_Castilla_elastica_incense_idols_ball_game_balls_Guatemala_Chiapas_Mexico_Belize_Hevea_brasiliensis.php |title=Introduction to Rubber Usage among the Maya |author=Langenheim, J.H. |date=13 January 2010 |publisher=Maya Archaeology|access-date=29 May 2017}}</ref> Early attempts were made in 1873 to grow ''H. brasiliensis'' outside [[Brazil]]. After some effort, 12 seedlings were germinated at the [[Royal Botanic Gardens, Kew]]. These were sent to [[India]] for cultivation, but died. A second attempt was then made, some 70,000 seeds being smuggled to Kew in 1875, by [[Henry Wickham (explorer)|Henry Wickham]], in the service of the British Empire.<ref name=df>"The Brazilian Armed Forces: Current changes, new challenges", ''Dreifuss, R. Armand''. In JOHN OLSLICK ELDER STREET THIEF KKALAJOA554977
International Seminar Research Committee Armed Forces and Society, [[Romania]], 2002. Retrieved August 19, 2009 from {{cite web |url=http://www.nestbrasil.com/rest/page8/files/rested1-dreyfus.pdf |title=Archived copy |access-date=2009-08-19 |url-status=dead |archive-url=https://web.archive.org/web/20090731102816/http://www.nestbrasil.com/rest/page8/files/rested1-dreyfus.pdf |archive-date=2009-07-31 }}</ref>{{RP|55}}<ref name=gp>"Amazon - The Animation", ''Greepeace Digital''. Artificial Environments, n/d. Retrieved August 19, 2009 from {{cite web |url=http://www.ae-pro.com/preview.php?preid=31&pro=Amazon |title=The Animation |access-date=2009-08-19 |url-status=dead |archive-url=https://web.archive.org/web/20110707090719/http://www.ae-pro.com/preview.php?preid=31&pro=Amazon |archive-date=2011-07-07 }}</ref><ref name=mag>"Acre: História e etnologia", ''Marco António Gonçalves (Org.)''. Núcleo de Etnologia Indígena Laboratório de Pesquisa Social/IFCS - UFRJ, n/d. Retrieved August 19, 2009 from http://eduardoeginacarli.blogspot.com/2007_07_01_archive.html {{Webarchive|url=https://web.archive.org/web/20180901113528/http://eduardoeginacarli.blogspot.com/2007_07_01_archive.html |date=2018-09-01 }}</ref> About four percent of these germinated, and in 1876, about 2,000 seedlings were sent, in [[Wardian case]]s, to [[Ceylon]] (modern day Sri Lanka) and 22 were sent to the botanic gardens in [[Singapore]].

[[File:“Henry Wickham, who in 1876 directed an operation smuggling 70,000 rubber tree seeds”.jpg|thumb|“Henry Wickham, who in 1876 directed an operation smuggling 70,000 rubber tree seeds”]]

Once established outside its native country, rubber was extensively propagated in the British colonies. Rubber trees were brought to the botanical gardens at [[Bogor|Buitenzorg]], Java, in 1883.<ref name="winchester">{{cite book | last = Winchester | first = Simon | author-link = Simon Winchester | title = [[Krakatoa: The Day the World Exploded, August 27, 1883]] | pages = [https://archive.org/details/krakatoadaywo00winc/page/223 223–224] | publisher =[[HarperCollins]]| year = 2003 | isbn = 0-06-621285-5 }}</ref> By 1898, a rubber plantation had been established in [[British Malaya|Malaya]], with imported Chinese field workers being the dominant work force in rubber production in the early 20th-century.<ref>Harold A. Crouch, ''Economic Change, Social Structure, and the Political System in Southeast Asia'', Institute of Southeast Asian Studies: Singapore 1985, pp. 16–17 {{ISBN|9971-988-23-2}}</ref>

The cultivation of the tree in South America (Amazon) ended early in the 20th century because of indigenous [[blight]]s that targeted the rubber tree.<ref name=eb>"Elastomer-The rubber tree", ''Encyclopædia Britannica'', 2008</ref> The blight, called South American leaf blight, is caused by the [[Ascomycota|ascomycete]] ''[[Pseudocercospora]] [[Pseudocercospora ulei|ulei]]'',<ref name="Guyot-Guen-2018">{{cite journal | last1=Guyot | first1=Jean | last2=Le Guen | first2=Vincent | title=A Review of a Century of Studies on South American Leaf Blight of the Rubber Tree | journal=[[Plant Disease (journal)|Plant Disease]] | publisher=[[American Phytopathological Society]] | volume=102 | issue=6 | year=2018 | issn=0191-2917 | doi=10.1094/pdis-04-17-0592-fe | pages=1052–1065| pmid=30673445 | doi-access=free }}</ref><ref name="EPPO-GD">{{cite web | title=''Pseudocercospora ulei'' (MICCUL){{bracket|Overview}} | website=Global Database | publisher=EPPO ([[European and Mediterranean Plant Protection Organization]]) | date=2002-04-09 | url=http://gd.eppo.int/taxon/MICCUL | access-date=2021-08-28}}</ref><ref>[http://journals.plos.org/plosone/article?id=10.1371/journal.pone.0104750#pone-0104750-g006 Erasing the Past: A New Identity for the Damoclean Pathogen Causing South American Leaf Blight of Rubber]</ref> also called ''Microcyclus ulei'',<ref>[http://www.plantwise.org/knowledgebank/datasheet.aspx?dsid=33893 South American Leaf Blight of rubber (''Microcyclus ulei'')], plantwise.org</ref> or ''Dothidella ulei'', which is endemic to the Amazon Basin. The blight was considered one of the five most aggressive diseases in commercial crops in South America.<ref name="Correa‑Pinilla2022">{{cite journal |last1=Correa‑Pinilla |first1=Diana Elisa |last2=Gutiérrez‑Vanegas |first2=Albert Julesmar |last3=Gil‑Restrepo |first3=Juan Pablo |last4=Martínez-Atencia |first4=Judith |last5=Córdoba‑Gaona |first5=Oscar de Jesús |title=Agroecological and South American leaf blight escape zones for rubber cultivation in Colombia |journal=Agronomy Journal |date=September–October 2022 |volume=114 |issue=5 |pages=2830–2844 |doi=10.1002/agj2.21068 |doi-access=free |bibcode=2022AgrJ..114.2830C }}</ref>
Rubber production then moved to parts of the world where it is not indigenous, and therefore not affected by local plant diseases.<ref>{{cite book |editor1-last= Prance |editor1-first=Ghillean |editor2-last=Nesbitt |editor2-first=Mark |last1=Prance |first1=Ghillean |date=2005 |title=The Cultural History of Plants |publisher=Routledge |page=28 |isbn=0415927463}}</ref> Today, most rubber tree plantations are in [[South Asia|South]] and [[Southeast Asia]], the top rubber producing countries in 2011 being Thailand, Indonesia, Malaysia, India and Vietnam.<ref>{{cite web |url=https://top5ofanything.com/list/7738a992/Rubber-Producing-Countries |title=The Top 5 Rubber Producing Countries |publisher=Top 5 of Anything |access-date=29 May 2017}}</ref>

==Environmental concerns==
The toxicity of arsenic to [[insect]]s, [[bacteria]], and [[fungi]] has led to the heavy use of [[arsenic trioxide]] on rubber plantations, especially in [[Malaysia]].<ref name=Ullmann>{{Ullmann | first1= Sabina C. |last1=Grund |first2=Kunibert |last2=Hanusch |first3=Hans Uwe |last3=Wolf | title = Arsenic and Arsenic Compounds | doi = 10.1002/14356007.a03_113.pub2}}</ref>

The majority of the rubber trees in Southeast Asia are clones of varieties highly susceptible to the South American leaf blight—''Pseudocercospora ulei''.  For these reasons, environmental historian Charles C. Mann, in his 2011 book, ''1493: Uncovering the New World Columbus Created'', predicted that the Southeast Asian rubber plantations will be ravaged by the blight in the not-too-distant future, thus creating a potential calamity for international industry.<ref>{{cite book|last=Mann|first=Charles C.|title=1493: Uncovering the New World Columbus Created|year=2011|publisher=Knopf|location=New York|isbn=978-0-307-26572-2|url=https://archive.org/details/1493uncoveringne00mann}}</ref>

==Secondary metabolites==
''Hevea brasiliensis'' produces [[cyanogenic glycosides]] (CGs) as a defense, concentrated in the seeds. (Although effective against other attackers, cyanogenic glycosides are not very effective against [[fungal plant pathogen|fungal pathogens]]. In rare cases, they are even detrimental. This is the case for the rubber tree, which actually suffers ''worse'' from ''Pseudocercospora ulei'' when it produces more cyanogenic glycosides. This may be because cyanide inhibits the production of other defensive metabolites. This results in significantly divergent subpopulations with selection for or against cyanogenic glycosides, depending on local likelihoods of fungal or non-fungal pest pressure.) The carbon and nitrogen in CGs are recycled for growth and latex production if needed, and the ease of doing so makes them an attractive nitrogen store - especially if the plant is light-deprived and storage in photosynthesis proteins would thus be unhelpful. The [[α-hydroxynitrilase|α-hydroxynitrile]]s are likely contained in the [[cytoplasm]]. [[Linamarin]] is [[hydrolysis|hydrolyzed]] by an accompanying [[linamarase]], a [[β-glycosidase]]. ''Hevea brasiliensis'' linamarase ''does'' act upon linamarin because it is a [[monoglucoside]], while it does ''not'' for [[linustatin]] because it is a diglucoside - in fact, the production of lovastatin inhibits linamarase cleavage of linamarin. This allows intra-plant, post-synthesis transport of linustatin without risking premature cleavage.<ref name="Gleadow-Moller-2014">{{cite journal | last1=Gleadow | first1=Roslyn M. | last2=Møller | first2=Birger Lindberg | title=Cyanogenic Glycosides: Synthesis, Physiology, and Phenotypic Plasticity | journal=[[Annual Review of Plant Biology]] | publisher=[[Annual Reviews (publisher)|Annual Reviews]] | volume=65 | issue=1 | date=2014-04-29 | issn=1543-5008 | doi=10.1146/annurev-arplant-050213-040027 | pages=155–185| pmid=24579992 | s2cid=207575721}}</ref>

==See also==
* ''[[Castilla elastica]]''—the principal source of latex rubber among the pre-Columbian [[Mesoamerica]]n peoples
* ''[[Landolphia owariensis]]''—a liana that was the primary source of Congo rubber
* [[List of plants of Amazon Rainforest vegetation of Brazil]]
* [[Congo Free State propaganda war|Red Rubber Scandal]]—was one of the first humanitarian global campaigns but concerned the rubber vine species
* [[Rubber seed oil]]
* [[Rubberwood]]

==Notes==
{{Reflist|2}}

==References==
{{refbegin}}
* Zhang, J., Huss, V.A.R., Sun, X., Chang, K. and Pan, D. 2008. Morphology and phylogenetic position of a trebouxiophycean green algae (Chlorophyta) growing on the rubber tree, ''Hevea brasiliensis'', with the description of a new genus and species. ''Eur. J. Phycol.'' '''43(2)''': 185–193.
*Charles C. Mann 2011.  1493. Uncovering the New World Columbus Created. Ch.7 Black Gold.
{{refend}}

==External links==
{{Commons category|Hevea brasiliensis}}
* {{YouTube|id=UPMJVnxZLgQ|title=Extraction of Rubber}}

{{Taxonbar|from=Q156538}}

[[Category:Crops originating from South America]]
[[Category:Crotonoideae]]
[[Category:Rubber]]
[[Category:Trees of Brazil]]
[[Category:Trees of Peru]]
[[Category:Trees of the Amazon rainforest]]