Intsia bijuga

''Intsia bijuga'', commonly known as Borneo teak, ipil, merbau, Johnstone River teak, and kwila, amongst many other names, is a species of tree in the flowering plant family Fabaceae, native to coastal areas from east Africa, through India and Southeast Asia to Australia and the western Pacific. It has significant importance to indigenous cultures in many parts of its range, but is also threatened by illegal logging due to its high quality timber. It is most commonly found in tropical coastal forests.

Description

''Intsia bijuga'' is an evergreen tree that usually grows to about tall but may reach , a trunk diameter between , and buttresses up to tall and wide. The compound leaves are arranged spirally on the twigs, and usually have four broadly oval-shaped and asymmetrical leaflets, each measuring up to long by wide.

The inflorescences are terminal and carry many bisexual flowers (i.e. flowers that have both male and female parts). Only one petal is fully developed and is up to long; it is initially white and turns pink or red with age. The fruit is a rather flat woody pod measuring between long and broad, with up to 8 disc-shaped seeds about diameter and thick.

Phenology

In Australia, flowering occurs from December to May.

Taxonomy

The species was first described as ''Macrolobium bijugum'' by the English botanist Henry Thomas Colebrooke in 1819, and was transferred to the genus ''Intsia'' by the German botanist Carl Ernst Otto Kuntze in 1891.

Etymology

The derivation of the genus name ''Intsia'' is uncertain, but it has been suggested it may come from the Malayalam name for ''Acacia intsia''. The species epithet ''bijuga'' is from the Latin words ''bi'' (two) and ''jugus'' (paired), and is a reference to the (usually) two pairs of leaflets in the compound leaf.

Vernacular names

Due to the wide distribution of this species, spanning many different language and cultural areas, there are many common names for this tree. Some of these names are Borneo teak, intsia, Johnstone River teak, Moluccan ironwood, Pacific teak, scrub mahogany and teak in English; and bendora, ifit, ipil, kayu besi, kwila, melila, merbau asam, merbau ayer, merbau ipil, tashiro-mame, and vesi in other languages across its range.

Distribution and habitat

The natural range of ''Intsia bijuga'' is, in broad terms, the Indo-Pacific region. It is native to Tanzania in Africa; the Chagos Archipelago, Madagascar, Mauritius and the Seychelles in the western Indian Ocean; Bangladesh, India and Sri Lanka in the Indian subcontinent; Andaman Islands, Cambodia, Myanmar, Nicobar Islands, Thailand and Vietnam in Indo-China; Taiwan in the South China Sea; Borneo, Java, Malaysia, Maluku, the Philippines, Sulawesi and Sumatra in Malesia; the Bismarck Archipelago, New Guinea and the Solomon Islands in Papuasia; the Northern Territory and Queensland in Australia; and the Caroline Islands, Fiji, the Marianas, the Marshall Islands, New Caledonia, Palau, Samoa, Santa Cruz Islands, Tonga and Vanuatu in the western Pacific Ocean.

The species is mostly coastal and inhabits beach forest and the upper reaches of mangrove forest, but it can also be found in rainforest and may even occur up to altitude.

Uses

The timber of this species is a very durable and termite-resistant wood, making it a highly valued and versatile building material with applications in engineering and construction as well as decorative work. It has a density of and an above-ground life expectancy of more than 40 years.

The tree had many uses in the indigenous communities where the tree is found — the timber was used for house building and for construction of canoes and rafts, and for the carving of ornaments and tools. A dye can be extracted from the wood and an insect repellent can be made from the seeds.Decoctions from various parts of the tree have been used to treat a range of ailments such as diarrhoea, rheumatism, pain, colds and influenza.

Conservation

, ''Intsia bijuga'' was classified on a world-wide scale as near threatened by the International Union for Conservation of Nature (IUCN), however, various regional authorities have given it different ratings. For example, in Queensland, Australia, it has been given least concern status, whereas in the neighbouring Northern Territory it is listed as critically endangered. It is also listed as critically endangered in Singapore, but as vulnerable in India.

Illegal logging

It is believed that the species now exists in large numbers only on the island of New Guinea, and that illegal logging is being carried out there as well as Indonesia and Malaysia. In 2007 Greenpeace accused China of importing large amounts of illegally-felled ipil logs from New Guinea, and claimed at the time that at the current rate of logging "the species will be virtually wiped out in the next 35 years".

Greenpeace have targeted users in Western countries in order to halt the trade in ipil. In New Zealand attempts have been made to stop it from being imported. In 2008 retailers were divided as to whether the sale of the timber should be banned. Jim Anderton, who was the Minister in charge of the Ministry of Agriculture and Forestry at that time, did not support a ban and instead he left it up to consumer choice.

, illegal harvesting of the trees was still going on in New Guinea.

Culture

''Intsia bijuga'' is the official tree of the United States territory of Guam and is a culturally important tree throughout the rest of the Marianas. The ''Tivia'' clan of Suburam village on the north coast of Papua New Guinea believe that the timber has spiritual powers, and the tree is sacred to Fijian people.

Gallery

File:Intsia bijuga 402449624.jpg, Trunk with buttresses
File:Even pinnate leaflets of Intsia bijuga.jpg, Foliage
File:Intsia-bijuga-SF24199-14.jpg, Flowers
File:Intsia-bijuga-SF24199-15.jpg, Immature fruit
File:Intsia bijuga 258174434.jpg, Mature fruit
File:Intsia-bijuga-SF22162-04.jpg, Seeds
File:Intsia bijuga seedling growing in coral limestone karst. 1000 Steps trail, Pagat, Guam.jpg, Seedling in karst, Guam

References

Further reading

*
*

External links

See a map
of recorded occurrences of this species at the GBIF website
See observations
of this species on iNaturalist
View images
of this species on Flickriver.com
CIRAD Forestry Department — timber data

{{Taxonbar, from=Q12700996

bijuga
Trees of Africa
Flora of tropical Asia
Trees of the Pacific
Trees of Madagascar
Trees of Seychelles
Trees of Taiwan
Flora of the Zanzibar Archipelago
Fabales of Australia
Trees of Australia
Flora of Queensland
Plants described in 1891
Austronesian agriculture