Hevea brasiliensis

Rubber tree (Hevea brasiliensis), three-part leaves

The rubber tree or rubber tree (Hevea brasiliensis, Syn. Siphonia A.Juss brasiliensis ) is a native of South America plant from the family of the spurge family ( Euphorbiaceae ).

Even the term rubber tree, which is also used for non- related species Ficus elastica is continuous.

The tree has a great economic importance because its as natural rubber ( rubber) or natural rubber latex ( latex) designated milk juice is the most important natural source of this renewable raw material for rubber production. Much of the demand is met by petrochemical-derived synthetic rubber.

The rubber tree was widespread Through this intensive use and is primarily grown in plantations in Asia and other parts of the so-called rubber belt.

  • 3.1 harvest
  • 3.2 Re-use

Description

Hevea brasiliensis is a tree, the plant height of about 20 to 40 m and reaches into plantations trunk diameter of about 35 cm. The core and the sapwood is yellowish and has an unpleasant odor when fresh. The bark is light gray. In the soft bast of the trunk milk tubes run ( chyle vessels), through which the sap flows. This consists of 55-70 percent water and 30-40 % of rubber. The remaining substances are sugar, proteins, resins and waxes, which account for only 0.5-2 percent. The branching is uniform and the branches are more or less upright. The bark of the branches is smooth. The stalked leaves are in three parts. The leaves are dark to light green, with a prominent venation, usually 7 to 20 cm (up to 25 cm ) long and usually 3-8 cm (up to 10 cm) wide. The petioles are usually 6 to 20 cm (rarely up to 30 cm ) long. The average flake is longer than the lateral. Each year, the rubber tree is its leaves again. The stipules are lanceolate and about 1 mm long.

Directly under the accumulation of foliage leaves at the end of the branches up to a 20 cm long inflorescence with 0.5 mm long bracts is formed. Hevea brasiliensis is monoecious getrenntgeschlechtig ( monoecious ). The male flowers have a 1 mm long calyx and two circles, each with five stamens that are fused to a 1.5 mm-high column. The female flowers have a about twice as large as the male calyx. The ovary is almost spherical and the pen is 0.3 mm long.

The fruit is about 4 × 4.5 cm in size. The egg-shaped to cylindrical seeds are about 2.3 × 1.5 cm in size, light gray with dark gray spots or stripes.

History and distribution

Origin

Originally, the occurrence was restricted to the tropical Amazon basin. The Indians called the plant also "ca -hu -chu ", which means as much as " weeping wood ". In the 15th century, the Portuguese were the first to latex and recognized the positive characteristics, such as the possibility of waterproof clothing by coating it with the thick juice manufacture, similar to the tapa bark cloth from Polynesia. After the discovery of the manufacturing process of rubber ( by vulcanization of the rubber ) in 1839, demand increased tremendously and resulted in the Amazon region near Manaus and Belém to a rubber boom.

Dissemination through the rubber boom

Brazil held the world monopoly for decades, even after natural rubber was obtained in the African tropics. After several failed attempts by other succeeded in 1876 the adventurer Henry Wickham on behalf of the British India Office and the Royal Botanic Gardens at Kew ( Royal Botanic Gardens, Kew ) in London, to bring rubber tree seeds out of the country. In the East Asian territories of the Straits Settlements ( Malay Peninsula) arose after various setbacks in the 1890s, the first plantations that brought their products to the world market from 1905. Soon repressed British rubber from Malaya the Brazilian from the world market, and the United Kingdom exercised a monopoly over the global rubber trade.

Today's distribution

At the present time the tree is planted, especially in the so-called rubber belt (approximately 30 ° north latitude to 30 ° south latitude ). The three largest producing countries are Thailand, Indonesia and Malaysia. The Brazilian stocks, however, are currently under serious threat from the South American leaf fall disease, the cause of the parasitic fungus Microcyclus is ulei. This fungus is also, in addition to mismanagement, blamed for the decline of the built in the early 20th century by Henry Ford, owner of the Ford Group in Brazil rubber plantation Fordlândia. The fungus infects the rubber tree, especially in the approximately two -week phase in which a new leaf develops. In humid equatorial climate to develop new leaves throughout the year, so that the tree is very susceptible to infection. In regions marked by seasons of the fungal though, has less opportunities for infestation. This is, for example, in the embossed by cooler and drier winter state of São Paulo is the case, so that today about 60 % of Brazil's rubber is produced there.

A large part of the global rubber demand (forecast: 23.9 million tonnes in 2009 ) today by synthetic rubber (forecast: 13.5 million tonnes in 2009 ) is covered. Nevertheless, it is expected in the future with an increase in the demand for natural rubber (forecast: 10.4 million tonnes in 2009 ). In 2019, is expected to rubber demand of 30.4 million tons, of which 14.0 million tonnes of natural rubber to make. Therefore, to expect a significant expansion of arable land.

Use

Harvest

After about five to six years the crop is old enough for the extraction of milk juice, called the rubber tree as natural rubber or latex. The milk tubes run counter-clockwise at an angle of 3.5 ° to the vertical direction. Therefore, the PTO cut is made in a spiral with a special knife from top left to bottom right at an angle of 30 ° to the horizontal direction. When cutting the location under the latex tubes cambium may be destroyed in any case, otherwise no regeneration of the cortex and thus the milk tubes is possible. The milky juice comes out and is collected in small buckets. The cut is only about half the circumference of the tree, so that a live strip secures the water and nutrients.

Reuse

At the age of about 25 years, the tree is a production of latex, so he likes ( in plantation economy ) and is replaced by new plants. The waste wood ( " rubberwood ", ~ 50 million cubic meters per year) is with its bright, warm color trend and is due to its high hardness (~ 6.2 according to the Brinell hardness test, and thus much harder than, for example, beech (~ 4.1 ), Maple (~ 4.7 ) or oak (~ 4.3 ) ) and its insensitivity to humidity variations more and more used for furniture making. The cultivated in monoculture plants make in some countries, such as Malaysia, already a large part of the furniture from wood. In Europe, it is increasingly being used for the interior. The wood is also made into a toy and is also used in musical instruments use.

Swell

  • A. Radcliffe -Smith: Euphorbiaceae in Flora Zambesiaca, Volume 9 Part 4, 1996 Online.. (English )
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