This is a photo of a rubber plant given to me by a friend. I found it a sunny spot in my sunroom/breakfast room and threw a cup of water on it infrequently. It seemed to thrive on my neglect. Then my friend decided she wanted to take the plant back for awhile because some of her plants were doing so well, and she wanted something nice to look at. Recently, she told me to take the plant back because it didn’t seem to like her care. When I picked it up, the saucer was full of water, so I suspect she was watering it too much. Sometimes, neglect really does work with plants, depending on the species. The only other rubber plant I have seen was in Malaysia when I took a tour of a rubber plantation. It was across the border from Singapore where I was staying. The rubber trees were very sturdy and tall. Most of the workers were women who tapped the trees just like you do for maple syrup, only this was liquid rubber or latex. It was a very labor-intensive process. At any rate rubber plants can be very pretty as ornamental plants, and rubber trees are very functional. Let’s learn more about them.
According to Wikipedia, Ficus elastica, the rubber fig, rubber bush, rubber tree, rubber plant, Indian rubber bush or Indian rubber tree is a species of plant in the fig genus, native to eastern parts of South Asia and southeast Asia. It has become naturalized in Sri Lanka, the West Indies and the state of Florida.
Description
It is a large tree in the banyan group of figs, growing to 100–130 feet — rarely up to 195 feet — tall, with a stout trunk up to 6 feet 7 inches in diameter. The trunk develops aerial and buttressing roots to anchor it in the soil and help support heavy branches.
It has broad shiny oval leaves 4–14 inches long and 2–6 inches broad. Leaf size is largest on young plants occasionally to 171⁄2 inches long and much smaller on old trees, typically 4 inches long. The leaves develop inside a sheath at the apical meristem, which grows larger as the new leaf develops. When it is mature, it unfurls, and the sheath drops off the plant. Inside the new leaf, another immature leaf is waiting to develop.
Pollination and fruiting
As with other members of the genus Ficus, the flowers require a particular species of fig wasp to pollinate it in a co-evolved relationship. Because of this relationship, the rubber plant does not produce highly colorful or fragrant flowers to attract other pollinators. The fruit is a small yellow-green oval fig 1⁄2 inch long, barely edible; these are fake fruits that contain fertile seeds only in areas where the pollinating insect is present.
Range
The natural range of rubber ranges from Nepal in the north to Indonesia, Bhutan, northeastern India, Burma, China’s Yunnan province and Malaysia. It has been widely introduced in most tropical regions of the world, including Hawaii and the West Indies. Finally, in Europe, it can be found in the sheltered gardens of the Côte d'Azur or French Riviera and on the Spanish and Italian coast.
(a) Ummonoi Bridge in northeast India, with a span of 7 meters, is a typical example of a mature living root bridge. Other bridges have spans up to 53 meters. (b) is taken from the center of the bridge, looking towards the right-hand end of (a).
Cultivation and uses
In parts of India, people guide the roots of the tree over chasms to eventually form living bridges.
Ornamental
Ficus elastica is grown around the world as an ornamental plant, outside in frost-free climates from the tropical to the Mediterranean and inside in colder climates as a houseplant. Although it is grown in Hawaii, the species of fig wasp required to allow it to spread naturally is not present there.
Most cultivated plants are produced by vegetative propagation. This can be done by cuttings or by layering. This last method consists in notching the stem of the plant. The wound, which leaves the latex of the plant oozing, is coated with rooting hormones and tightly wrapped with moist foam. The hole is covered with a plastic film and left a few months when new roots develop from the axillary buds. The stem is then weaned, and the new plant can be repotted.
All parts of the plant contain an abundant milky white latex, which has been tested for use in the manufacture of rubber, but without economic and technical results; commercial rubber is actually produced from the sap of the Hevea brasiliensis.
In cultivation, it prefers bright sunlight but not hot temperatures. It has a high tolerance for drought, but prefers humidity and thrives in wet, tropical conditions. Ornamental hybrids such as Robusta have been derived from Ficus elastica with broader, stiffer and more upright leaves than the wild form. Many such hybrids exist, often with variegated leaves.
Latex
Ficus elastica yields a milky white latex, a chemical compound separate from its sap and carried and stored in different cells. This latex was formerly used to make rubber, but it should not be confused with the Pará rubber tree or Hevea brasiliensis, the main commercial source of latex for rubber making. Just as with Hevea brasiliensis, the latex of Ficus elastica is an irritant to the eyes and skin and is toxic if taken internally.
Hevea brasiliensis or Pará rubber tree
Hevea brasiliensis, Pará rubber tree, sharinga tree, seringueira or — most commonly — rubber tree or rubber plant is a flowering plant belonging to the spurge family Euphorbiaceae. 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
H. brasiliensis is a tall deciduous tree growing to a height of up to 141 feet in the wild, but cultivated trees are usually much smaller because drawing off the latex restricts the growth of the tree. 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 leaflets and are spirally arranged. The inflorescence 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.
Rubber tree plantation
In the wild, the tree can reach a height of up to 140 feet. The white or yellow latex occurs in latex vessels in the bark, mostly outside the phloem, the living tissue in vascular plants that transports the soluble organic compounds made during photosynthesis. 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 feet.
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 or subtropical climate with a minimum of about 1,200 mm per year of rainfall, and no frost. 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.
Latex tapping
The natural rubber tree takes between seven and ten years to deliver the first harvest. 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.
Rubber tapping is the process by which latex is collected from a rubber tree. The latex is harvested by slicing a groove into the bark of the tree at a depth of one-quarter inch with a hooked knife and peeling back the bark. Trees must be approximately six years old and six inches in diameter in order to be tapped for latex.
Rubber tapping is not damaging to the forest, as it does not require the tree to be cut down for the latex to be extracted. Jungle rubber is essentially old secondary forest, strongly resembling the primary forest. Its species' richness is about half that of the primary forest. Michon and de Foresta in1994) found that sample jungle rubber sites contained 92 tree species, 97 lianas and 28 epiphytes compared with 171, 89, and 63, respectively, in the primary forest, and compared with 1, 1, and 2 in monoculture estates. Thiollay in 1995 estimated that jungle rubber supports about 137 bird species, against 241 in the primary forest itself. Jungle rubber is expected to resemble primary forest in its hydrological functions. Mono culture rubber tree plantations have far less of an environmental impact than other crops, such as coffee or especially oil palm.
Each night a rubber tapper must remove a thin layer of bark along a downward half spiral on the tree trunk. If done carefully and with skill, this tapping panel will yield latex for up to five hours. Then the opposite side will be tapped, allowing this side to heal over. The spiral allows the latex to run down to a collecting cup. The work is done at night or in the early morning before the day's temperature rises, so the latex will drip longer before coagulating and sealing the cut.
Depending on the final product, additional chemicals can be added to the latex cup to preserve the latex longer. Ammonia solution helps prevent natural coagulation and allows the latex to remain in its liquid state. Plastic bags containing a coagulant have replaced cups in many plantations in Malaysia. This form of latex is used as the raw material for latex concentrate, which is used for dipped rubber products or for the manufacture of ribbed smoke sheet grades.
Naturally coagulated latex, sometimes referred to as cup lump, is collected for processing into block rubbers, which are referred to as technically specified rubbers. The serum left after latex coagulation is rich in quebrachitol, a cyclitol or cyclic polyol.
Intensive tapping is done to older trees during its last years just before it is cut. It involves collecting maximum amount of latex by tapping frequently, making double cuts, using yield simulants, etc. Slaughter tapping refers to the destructive tapping that was done in late 19th century to extract large quantities of natural latex.
Wood harvesting
As latex production declines with age, rubber trees are generally 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.
Rubberwood is a light-colored medium-density tropical hardwood obtained from the Pará rubber tree, usually from trees grown in rubber plantations. Rubberwood is commonly advertised as an "environmentally friendly" wood, as it makes use of plantation trees that have already served a useful function.
Rubberwood is also known as plantation hardwood, parawood or "Hevea" for the genus that the tree belongs to. In 2002, the Malaysian Ministry of Primary Industries marketed it under the name "Malaysian Oak."
Although it had been used on a small scale before, its use for furniture-making has become much more common in the late 20th and early 21st century with the development of chemical treatments to protect the wood against fungal and insect attacks. There are extensive rubber plantations with mature trees, especially in southeast Asia; the earlier practice was to burn the tree at the end of its latex-producing cycle.
Currently, rubber plantation trees are generally harvested for wood after they complete the latex producing cycle, when they are 25 to 30 years old. When the latex yields become extremely low, the trees are then felled, and new trees are usually planted. This makes rubberwood “eco-friendly” in that the wood is harvested from a renewable source. The wood from the trees is light in color and straight-grained making it easy to stain and match in woodworking. Part of the industry adoption of rubberwood was an international campaign to avoid use of a previously used light straight-grained wood which was harvested from southeast Asia's endangered wetland ramin or Gonystylus, a southeast Asian genus of about 30 species of hardwood trees also known as ramin, melawis (Malay) and ramin telur (Sarawak).
Rubberwood is susceptible to fungal and insect attack that limited its use in the past. However, in the 1980s, the development of chemical treatment processes allowed the wood to be more widely used for furniture making and frames. Today, rubberwood is generally treated soon after sawing by pressurized immersion in boron preservatives, followed by kiln-drying to diffuse the chemicals and to control moisture content.
Rubberwood has a dense grain that is easily controlled in the kiln drying process. Rubberwood has very little shrinkage making it one of the more stable construction materials available for furniture, toys and kitchen accessories. It is easily worked, and takes on stains uniformly. As with all hardwoods, rubberwood comes in varying degrees of quality.
It is not suitable for outdoor use, as rain can leach the protective chemicals from the wood, exposing it to fungus and insect attacks. Excessive moisture will also cause the wood to warp and rot.
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, 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 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. Early attempts were made in 1873 to grow H. brasilensis outside Brazil. After some effort, 12 seedlings were germinated at the Royal Botanic Gardens in 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 in the service of the British Empire. About four percent of these germinated, and in 1876, about 2,000 seedlings were sent in Wardian cases — an early type of terrarium — to Ceylon or 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. By 1898, a rubber plantation had been established in Malaya, with imported Chinese field workers being the dominant work force in rubber production in the early 20th-century.
The cultivation of the tree in South America in the Amazon rainforest ended early in the 20th century because of indigenous blights that targeted the rubber tree. The blight, called South American leaf blight, is caused by the ascomycetes Microcyclus ulei, also called Pseudocercospora ulei or Dothidella ulei. Rubber production then moved to parts of the world where it is not indigenous, and therefore not affected by local plant diseases. Today, most rubber tree plantations are in South and Southeast Asia, the top rubber producing countries in 2011 being Thailand, Indonesia, Malaysia, India and Vietnam.
Environmental concerns
The toxicity of arsenic to insects, bacteria and fungi has led to the heavy use of arsenic trioxide on rubber plantations, especially in Malaysia.
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,” 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.
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