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Overview

Brief Summary

Hevea brasiliensis, the rubber tree or Pará rubber tree, is a medium to large tropical tree in the Euphorbiaceae (spurge family) native to South America (the Brazilian and Bolivian region covering Amazon and Orinoco river basins), which produces a milky sap (latex) that is the primary source of natural rubber. Although some wild-grown trees are still tapped for their sap, most commercial production now comes from rubber tree plantations in southern and southeastern Asia (including Indonesia, Malaysia, and Sri Lanka), as well as western Africa.

Other species that contain latex that may be used for natural rubber production include gutta-percha (Palaquium gutta), rubber fig (Ficus elastica), and Panama rubber tree (Castilla elastica), although none are used to the same extent as H. brasiliensis.

The rubber tree may grow to 30 m (100 ft) or more where it occurs in the wild, although plantation trees generally reach heights of around 17 m (60 ft). The thick, leathery leaves, up to 60 cm (24 in) long, are compound, with 3 elliptic leaflets, each with entire (unserrated) margins and prominent secondary veins. The inflorescence is a many-flowered panicle (a much-branched cluster), up to 16 cm (6.5 in) long, with a small white petal-less female flower in the center, surrounded by small 5-lobed or dissected male flowers. The fruit is a large ellipsoidal capsule, usually 3-valved and 5 to 6 cm in diameter (2 to 2.5 in), containing gray-brown, flattened ellipsoidal seeds.

The sap, which can be harvested from the inner bark when the tree reaches 6 or 7 years, is obtained by tapping—cutting the bark and letting the sap drip out, then coagulated. Amazonian natives had long used the rubber that naturally forms from the latex, including to make balls used in early games, but the untreated rubber would become soft and sticky in the heat, and brittle in the cold. This problem was remedied by the chemical process known as vulcanization, developed by Charles Goodyear in the 1840s, which allows rubber to remain firm but flexible in all temperatures. Vulcanization allowed natural rubber products to become commercially successful, and promoted commercial plantations in tropical areas in Asia and Africa.

In 2010, 11 countries accounted for 92% of global production of natural rubber from H. brasiliensis: Cambodia; China; India, Indonesia; Malaysia; Papua New Guinea; Philippines; Singapore; Sri Lanka; Thailand; and Vietnam. Natural rubber is not produced in significant amounts in its native South America, because trees there are widely affected by South American leaf blight, caused by the fungus Microcyclus ulei (Ascomycota).

Synthetic rubber, which is processed from petroleum and was developed during the 1920s through 1940s, now makes up roughly 70% of the rubber manufactured worldwide, but natural rubber continues to have important uses in manufacturing and textiles.

(ANRPC 2012, Bailey et al. 1976, Encyclopedia Britannica 1993, Flora of China 2008, Wikipedia 2012.)

  • ANRPC. 2012. Association of Natural Rubber Producing Countries web site: http://www.anrpc.org/.
  • Bailey, L.H., E.Z. Bailey, and the L.H. Bailey Hortatorium. 1976. Hortus Third: A concise dictionary of plants cultivated in the United States and Canada. New York: Macmillan. p. 560.
  • Encyclopedia Britannica. 1993. “Rubber.” Encyclopedia Britannica Micropaedia vol. 10: 223. Chicago: Encyclopedia Britannica, Inc. 15th ed.
  • Flora of China. 2008. Hevea Aublet, Hist. Pl. Guiane 2: 871. 1775. Flora of China 11: 264–265. Accessed online: http://flora.huh.harvard.edu/china/PDF/PDF11/Hevea.pdf.
  • Wikipedia. 2012. Natural rubber [Internet]. Wikipedia, The Free Encyclopedia. 2012 Jul 7, 05:13 UTC [cited 2012 Jul 8]. Available from: http://en.wikipedia.org/w/index.php?title=Natural_rubber&oldid=501056267.
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Comprehensive Description

Miscellaneous Details

"Notes: Cultivated, Occasionally planted in other districts, Native of Tropical America"
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Distribution

"Karnataka: Chikmagalur, Coorg Kerala: All districts Tamil Nadu: Kanniyakumari"
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Physical Description

Morphology

Description

Large trees, up to 30 m tall, with much milky juice. Petiole 5-15 cm, apex usually with 2(-4) glands; leaflets 3, elliptic, 10-25 × 4-10 cm, both surfaces glabrous, base cuneate, margin entire, apex acute to acuminate; lateral veins 10-16, reticulate veins prominent. Panicles axillary, to 16 cm, gray-white pubescent. Male flowers: sepals ovate-lanceolate, ca. 2 mm; stamens 10, in 2 series; anthers 2-locular, longitudinally dehiscent. Female flowers: sepals as in male, but larger; ovary (2 or)3(-6)-locular; stigmas 3, sessile. Capsules ellipsoidal, 5-6 cm in diam., with 3 longitudinal grooves, apex rostrate, base retuse; epicarp thinner, with reticulate stripes; endocarp thicker, woody. Seeds ellipsoidal, gray-brownish, maculate-striate. Fl. May-Jun, fr. Aug-Sep.
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Diagnostic Description

Diagnostic

Habit: Tree
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Synonym

Siphonia brasiliensis Willdenow ex A. Jussieu, Euphorb. Gen. t. 12. 1824.
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Ecology

Habitat

Habitat & Distribution

Cultivated. S Fujian, Guangdong, Guangxi, Hainan, Taiwan, Yunnan [native to Brazil; widely introduced throughout the tropics].
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Evolution and Systematics

Functional Adaptations

Functional adaptation

Trees self-repair: Pará rubber tree
 

Bark of the rubber tree self-repairs due to cross-linking of rubber particles that cause coagulation.

     
  "Self-healing strategies found in nature may thus serve as concept generators for biomimetic self-healing elastomers that stop or even heal micro-cracks. Plant secretions, such as resins and particularly lattices, are suitable as role models. Upon injury of a latex bearing plant, this healing agent is discharged and results in closure of the wound by coagulation as described by d’Auzac et al [1989]. He suggests a pressure-dependent release of the protein Hevein upon injury that cross-links rubber particles, and thus leads to latex coagulation. A comparison of the coagulation mechanisms of several latex bearing plant species may reveal similarities or differences among them allowing one to adjust technical self-healing systems under various conditions." (Brebbia and Carpi 2010:454)
  Learn more about this functional adaptation.
  • Brebbia CA; Carpi A. 2010. Design and nature V. Southhampton, UK: WIT Press. 604 p.
  • d'Auzac J; Jacob J-L; Chrestin H. 1989. Physiology of rubber tree latex: The laticiferous cell and latex : a model of cytoplasm. Boca Raton, Florida: CRC Press. 470 p.
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Molecular Biology and Genetics

Molecular Biology

Statistics of barcoding coverage: Hevea brasiliensis

Barcode of Life Data Systems (BOLDS) Stats
Public Records: 0
Specimens with Barcodes: 1
Species With Barcodes: 1
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Wikipedia

Hevea brasiliensis

For the common ornamental plant, see Ficus elastica.

Hevea brasiliensis, the Pará rubber tree, sharinga tree, or, most commonly, the rubber tree, is a tree belonging to the family Euphorbiaceae. It is the most economically important member of the genus Hevea. It is of major economic importance because the milky latex extracted from the tree is the primary source of natural rubber.

Rubber tree plantation[edit]

Rubber tree seeds

In the wild, the tree can reach a height of up to 100 feet (30 m). The white or yellow latex occurs in latex vessels in the 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 45 ft.

In plantations, the trees are generally smaller for two reasons: 1) Trees grow slower when they are tapped for latex, and 2) trees are generally cut after 30 years because latex production declines as trees age, and they are no longer economically viable.

The tree requires a tropical or subtropical climate with a minimum of about 1200 mm/yr of rainfall, and without frost.[1] 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 (needs reference).

Harvest of latex[edit]

Main article: Rubber tapping
Rubber tree trunk
Latex being collected from an incised rubber tree and a bucket of collected latex

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.

History[edit]

The Pará rubber tree initially grew only in the Amazon Rainforest. Increasing demand and the discovery of the vulcanization procedure in 1839 led to the rubber boom in that region, enriching the cities of Belém and Manaus. The name of the tree derives from Pará, the second-largest Brazilian state, the capital of which is Belém.

These trees were 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 3600 years ago.[citation needed] The rubber was used, among other things, to make the balls used in the Mesoamerican ballgame.[citation needed] Early attempts were made in 1873 to grow H. brasilensis 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, at the service of the British Empire.[2][3][4][5] About 4% of these germinated, and in 1876, about 2000 seedlings were sent, in Wardian cases, to Ceylon (modern day Sri Lanka) and 22 were sent to the Botanic Gardens in Singapore. Once established outside its native country, rubber was extensively propagated in the British colonies. Rubber trees were brought to the botanical gardens at Buitenzorg, Java, in 1883.[6] By 1898, a rubber plantation had been established in Malaya, and today, most rubber tree plantations are in South and Southeast Asia, with some also in tropical West Africa.

Efforts to cultivate the tree in South America (Amazon) were unsatisfactory because of blight.[1] The blight, called South American leaf blight, is caused by the Ascomycota, Microcyclus ulei.[7]

Environmental concerns[edit]

The toxicity of arsenic to insects, bacteria, and fungi has led to the heavy use of arsenic trioxide on rubber plantations, especially in Malaysia.[8]

The majority of the rubber trees in Southeast Asia are clones of varieties highly susceptible to the South American leaf blight--Microcyclus ulei. For these reasons, environmental historian Charles C. Mann, in his 2011 book, 1493: Uncovering the New World Columbus Created, predicts 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 (p275-278).

Synonyms[edit]

The genus Hevea is also known as:

Gallery[edit]

See also[edit]

Notes[edit]

  1. ^ a b "Elastomer-The rubber tree", Encyclopaedia Britannica, 2008
  2. ^ "The Brazilian Armed Forces: Current changes, new challenges", Dreifuss, R. Armand. International Seminar Research Committee Armed Forces and Society, Romania, 2002. Retrieved August 19, 2009 from http://www.nestbrasil.com/rest/page8/files/rested1-dreyfus.pdf (p. 55)
  3. ^ "Amazon - The Animation", Greepeace Digital. Artificial Environments, n/d. Retrieved August 19, 2009 from http://www.ae-pro.com/preview.php?preid=31&pro=Amazon
  4. ^ "Seringueira", Wikipédia, a enciclopédia livre, 2009. Retrieved 11h05min, August 19, 2009 from http://pt.wikipedia.org/w/index.php?title=Seringueira&oldid=15936263
  5. ^ "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
  6. ^ Winchester, Simon (2003). Krakatoa: The Day the World Exploded, August 27, 1883. HarperCollins. pp. 223–224. ISBN 0-06-621285-5. 
  7. ^ South American Leaf Blight, plantwise.org
  8. ^ Sabina C. Grund, Kunibert Hanusch, Hans Uwe Wolf (2005), "Arsenic and Arsenic Compounds", Ullmann's Encyclopedia of Industrial Chemistry, Weinheim: Wiley-VCH, doi:10.1002/14356007.a03_113.pub2 

References[edit]

Further references[edit]

  • 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.
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Notes

Comments

This species is cultivated in great numbers for the production of rubber.
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Economic Significance

This tree is extremely valuable to humans, it is the source of latex and natural rubber and is the most economically important crop of the genus Hevea. It is grown on monoculture crop plantations mostly in South America and some parts of Africa.

  • B.C. Bennett.  2007.  Chapter 3:  Twenty-five Important Plant Families.  B.C. Bennett, editor.  UNESCO Encyclopedia of Life Support Systems.  http://eolss.net.
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