Botanical Name: Bruguiera gymnorrhiza
Species: B. gymnorhiza
*Bruguiera capensis Blume
*Bruguiera conjugata (L.) Merr.
*Bruguiera gymnorhiza (L.)
*Bruguiera rheedei Blume
*Bruguiera rumphii Blume
*Bruguiera wightii Blume
*Bruguiera zippelii Blume
*Rhizophora conjugata L.
*Rhizophora gymnorhiza L.
*Rhizophora palun DC.
*Rhizophora rheedei Steud.
*Rhizophora tinctoria Blanco
Common Names: Black Mangrove
As well as its botanical name, the tree is known by many common, or vernacular names. These include: Tongan: tongo; Marshall Islands jon; Kosrae sraol; Pohnpei sohmw; Chuuk ong; Yap yangach; northern Australia orange mangrove; Wanigela, Northern (Oro) Province, Papua New Guinea kavela, mangrove bean.; Thyanhngayth dialect, Awngthim language nhomb; Sapek people, Supiori, Papua Province, Indonesia arouw Batjamal benmerr; Emi kunyme; Palau denges; Indonesian: putut; Malay: pokok tumu merah; Khmer prâsak’ nhi, prâsak’ toch, prâsak’ tük; Thai: ?????????????????; Bengali: Kankra gach; Telugu (Andhra Pradesh) thuddu ponna, uredi; Maldives bodu ka???, boda vaki.; Kiswahili (Kenya, Tanzania, including Zanzibar, Mozambique) muia, mkoko wimbi; Zulu: isihlobane; Xhosa: isikhangati; Afrikaans: swart-wortelboom; South African English black mangrove; English large-leafed mangrove, oriental mangrove.
The tree is found as a native on the coasts of places bordering the Indian Ocean, the South China Sea, and parts of the western Pacific Ocean. Regions that it is native to include: Caroline Island, Samoa, Tonga, Wallis and Futuna, Fiji, Marshall Islands, Gilbert Islands, Nauru, Vanuatu, Solomon Islands, Queensland, New Guinea, Northern Territory, Lesser Sunda Islands, Sulawesi, Nansei-shoto, Borneo, Jawa, Hainan, Christmas Island, Southeast China, Cambodia, Vietnam, Sumatra, Peninsular Malaysia, Thailand, Myanmar, Bangladesh, Nicobar Islands, Andaman Islands, India (including Andhra Pradesh), Sri Lanka, Maldives, Mauritius, Madagascar, Aldabra, Seychelles, Somalia, Djibouti, Kenya, Mozambique Channel Islands, Tanzania, Mozambique, KwaZulu-Natal, Cape Provinces.
The tree grows on intertidal mud-flats and estuaries, 0-2m (the elevation range between mean sea level and highest tide), on the less exposed parts of the coast, with a rainfall of 1000-8000mm. Common associates on Pacific Island include other mangrove species. The species grows on a wide range of soils, but does best in river estuaries, Salt water habitats on an alluvial sediment allows the tree to spread with its adventitious roots. The black mangrove is a protected tree in South Africa.
A tree that can grow up to 35m, though usually smaller, around 7-20m, it has a glabrous, smoothish, trunk with reddish brown bark (the bark is sometimes fibrous, sometimes lightish brown or grey). The tree develops short prop-roots rather than long stilt-roots. The green elliptic leaves are 5–15 cm long. Flowers are solitary, with white or cream petals, that soon turn brown up to 1.5 cm long, pinkish-green to reddish brown calyx. The fruit are turbinate (spinning-top shaped), 2 cm long, when mature, the spindle-shaped fruits drop and become embedded in the mud in an upright position, where they rapidly develop roots. The seeds, when still on tree, have a hypocotyl up to 11 cm long.
A plant of tropical and subtropical, moist to rainforest life zones, where it always grows near the coast at elevations up to 50 metres. It grows best in areas where annual daytime temperatures are within the range 20 – 26°c, but can tolerate 15 – 30°c. It can be killed by temperatures of °c or lower. It prefers a mean annual rainfall in the range 1,500 – 6,000mm, but tolerates 1,000 – 8,000mm.
Plants grow best on brackish or saline silts of depositing shores and marshes. The tree has proved to be able to grow, flower, fruit and even regenerate in artificial fresh water swamps. It can stand any amount of shade. Prefers a pH in the range 7 – 8, tolerating 6.5 – 8.5. Although it is a mangrove, it is sensitive to high salt concentrations, dying out when concentrations of sodium chloride exceed 3%.
Black mangrove marks the climax vegetation of littoral forests (mangroves), before the transition to land forest. It is a shade tolerant species that is able to establish itself even in pure stands of Rhizophora species.
It takes 40 years for trees to attain 16cm in bole diameter.
Plants do not respond well to lopping or coppicing.
It flowers abundantly in the rainy season.
Seedlings can remain alive, floating in the water, for 5 – 6 months, which possibly explains the large area of natural distribution.
Planting is usually not needed because natural regeneration is so successful. Regeneration after felling, however, is usually scant or even absent. The natural and artificial regeneration has never been extensively investigated.
Seed germinates whilst still attached to the tree. Seedlings can be collected either from the trees or from the ground, they are equally viable. They can be planted in a nursery, and transferred to the field 3 – 4 months later. Seedlings develop best where the tidal range is only about 0.35 metres and the salinity is 1 – 2.5%
The leaves and peeled hypocotyls are eaten in times of scarcity in the Moluccas after having been soaked in water to remove the astringent tannins and then boiled.
The starchy central part of the hypocotyl is treated with sugar and then eaten.
The fruits are sometimes used as an astringent in betel quid when nothing better is available.
The bark is used as a condimen.
The bark is used as an astringent medicine against diarrhoea and sometimes malaria. It is used as an abortifacient.
The bark is applied externally for treating burns.
A decoction of the root, combined with the leaves of Piper pyrifolium, is used as a remedy for bleeding, diabetes and hypertension.
The fruits are suitable as an eye medicine.
This species might be successfully used for reforestation in areas where mangroves have been destroyed. It is planted by the coast to provide protection from sea spray, storm surge, and salt-water incursion.
The tree has been planted in fresh water swamps and also to stabilize dunes.
Different other uses:
The bark is suitable for tanning as it contains up to 35% tanning substance in air-dry bark. It is often mixed with other tannins in the tanning industry. The tannins can be used to preserve fibres in ropes, sails etc. The tannin can be extracted by boiling the bark in large vessels and evaporating down to a solid.
As in other mangrove species, the percentage of tannin in the bark varies largely from 20% to 43% on dry weight basis, depending on age, season and habitat. The bark of the trunk of large, aged trees is richest in tannin.
A phlobaphene colouring matter from the bark is sometimes used as a dye for black or dark-brown colour, but this use is considered as minor.
The bark provides orange to reddish brown dyes without mordanting, and purplish brown, grey and black colours if the fibres or textiles are treated with iron-rich mud or iron salts.
The skin of the seeds is used to prepare a black dye for traditional skirts in the Pacific.
The heartwood is red brown; it is distinctly demarcated from the pale brown sapwood. The grain is usually interlocked, texture fine and even. The wood is heavy (about 980 kg/m cubic), strong, hard, moderately durable when exposed to the weather or in contact with the ground. It is used for piles, house posts, rafters, fishing stakes, and telegraph poles. Poles have a life of about 10 years. The wood can also be used for the paper industry, but the paper is of poor quality.
The timber is used for fuel and for making charcoal. It makes a very good fuel and charcoal. The energy value of the wood is 18,950–20,200 kJ/kg.