|Subgenus:||F. subg. Urostigma|
Ficus elastica, the rubber fig, rubber bush, rubber tree, rubber plant, or Indian rubber bush, 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 US State of Florida.
It is a large tree in the banyan group of figs, growing to 30–40 m (100–130 ft) – rarely up to 60 m or 195 ft – tall, with a stout trunk up to 2 m (6 ft 7 in) 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 10–35 cm (4–14 in) long and 5–15 cm (2–6 in) broad; leaf size is largest on young plants (occasionally to 45 cm or 17+1⁄2 in long), much smaller on old trees (typically 10 cm or 4 in 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.
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 colourful or fragrant flowers to attract other pollinators. The fruit is a small yellow-green oval fig 1 cm (1⁄2 in) long, barely edible; these are fake fruits that contain fertile seeds only in areas where the pollinating insect is present.
The natural range of rubber ranges from Nepal in the north to Indonesia, Bhutan, northeastern India, Burma and China (Yunnan) 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 and on the Spanish and Italian coast.
In parts of India, people guide the roots of the tree over chasms to eventually form living bridges.
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 at the end of which new roots have developed 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.
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 (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.
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