Botanical Name: Rhizophora mucronate
*Mangium candelarium Rumphius
*Rhizophora candelaria Wight & Arn.
*Rhizophora longissima Blanco
*Rhizophora macrorrhiza Griff.
Common Names: Garjan/ Bhara, Loop-root mangrove, Red mangrove or Asiatic mangrove
Rhizophora mucronata is found in the Indo-Pacific region on the banks of rivers and on the edge of the sea. It is the only mangrove species to be found in East Africa. R. mucronata is native to Africa (in southeastern Egypt; eastern Ethiopia; eastern Kenya; Madagascar; Mauritius; Mozambique; the Seychelles; Somalia; eastern side of South Africa down to Nahoon the southernmost mangrove forest in Africa; southeastern Sudan; and eastern Tanzania); Asia (in Burma; Cambodia; India; Pakistan; Iran; Indonesia; the Ryukyu Islands of Japan; Malaysia; Papua New Guinea; the Philippines; Sri Lanka; Taiwan; Thailand; and Vietnam) the South Pacific (in the Solomon Islands; and Vanuatu) and Australia (in northern Northern Territory; and northern Queensland).
The natural habitat of Rhizophora mucronata is estuaries, tidal creeks and flat coastal areas subject to daily tidal flooding. It seems to be more tolerant of inundation than other mangrove species and often forms an evergreen fringe to mangrove areas. It sometimes occurs as a pure stand or may grow with Rhizophora apiculata. The red mangrove is a protected tree in South Africa.
Rhizophora mucronata is a small to medium size evergreen tree growing to a height of about 20 to 25 metres (66 to 82 ft) on the banks of rivers. On the fringes of the sea 10 or 15 metres (33 or 49 ft) is a more typical height. The tallest trees are closest to the water and shorter trees are further inland. The tree has a large number of aerial stilt roots buttressing the trunk. The leaves are elliptical and usually about 12 centimetres (4.7 in) long and 6 centimetres (2.4 in) wide. They have elongated tips but these often break off. There are corky warts on the pale undersides of the leaves. The flowers develop in axillary clusters on the twigs. Each has a hard cream-coloured calyx with four sepals and four white, hairy petals. The seeds are viviparous and start to develop whilst still attached to the tree. The root begins to elongate and may reach a length of a metre (yard) or more. The propagule then becomes detached from the branch when sufficiently well developed to root in the mud below.
A plant of coastal areas of the moist to wet lowland tropics and subtropics. It grows best in areas where annual daytime temperatures are within the range 20 – 28°c, but can tolerate 15 – 32°c. It prefers a mean annual rainfall in the range 1,500 – 2,500mm, but tolerates 1,000 – 3,000mm.
Requires a sunny position. A plant of saline and brackish soils that are inundated by salt water at high tides, it is also often found in deep, soft mud. Plants can tolerate a pH in the range 6 – 8.5.Prefers a pH in the range 6.7 – 7.2, tolerating 6.5 – 7.5.
The tree grows slowly. In Peninsular Malaysia it takes 35 – 40 years to reach up to 19 cm in diameter. A 40-years rotation is favourable.
There is a characteristic development of the seed in this genus. One seed is developed per fruit and starts to germinate when the fruit is still attached or hanging on the tree; this phenomenon is known as viviparous germination and is common among mangrove plants. The root (radicle) gradually protrudes from the fruit, at first like a green cigar, then grows into a rod-like structure. In this species such a seedling root (hypocotyl) with a rough and warty surface may attain a considerable length (sometimes over 100 cm), the largest and longest in the genus. Later the seedling falls out of the fruit, drops into the mud and sooner or later begins to grow. The seedlings that have fallen into the water at high tide commonly drift to another place or are washed up on the shore; they retain their vitality for several months, and will survive and grow if the spot is ecologically suitable.
The main root of the seedling is usually abortive and lateral roots take over its function.
Through seeds- young seedlings, gathered from the wild, can be used for planting. Natural regeneration always occurs near mature trees. There is a form of vegetative spread of the trees by horizontal growth of the lower branches supported by stilt roots; these branches can continue to grow if the parent trunk dies.
The fruit is occasionally eaten. It is prepared by first boiling it, then adding wood ashes to neutralize the bitter taste. The fruit is then baked and eaten.
Used occasionally as a medicine in cases of haematuria. This probably refers to the bark.
A part of the mangrove swamps, the tree helps to protect inland areas from the effects of the ocean, including stabilizing the shore line and giving protection from strong winds and storms.
The bark is an important local source of tannin. It is used for tanning leather and to toughen and dye lines, nets, and ropes used by fishermen. According to laboratory investigations, mangrove tannin extracted from the bark could be used to produce adhesive for the manufacture of plywood and particle board.
The quantity of tannin in the bark may vary greatly. In air-dried bark the tannin content varies from 8 – 40%-310]. The tannin is sometimes extracted and concentrated into cutch. The bark, according to some chemical analyses, appears to contain high percentages of pentosans and furfurol.
The tannin of Rhizophora is associated with a substance which darkens gradually; it is used as a deep brown or black dye.
The ash, after the cutch has been extracted, consists mainly of lime (18%) and calcium carbonate (70%), and can be used as a fertilizer.
The wood shows a beautiful silver grain on radial section and the heartwood is dark orange-red. Its use, however, is limited because of its light weight, poor durability and small size of the trunk.
Another, somewhat contradictory report says that the heartwood is of a dark red colour with dark rings of growth; and is demarcated from the bright yellow sapwood. The wood is durable, very hard, and heavy. It is, however, very brittle, and warps and cracks so easily as to unfit it for cabinet use. The wood, in this report, is said to be durable in water and under-ground, and would be suitable for foundations of bridges and wharves.
A third report says thar the wood is used for heavy constructions, poles, piling, frames of houses, fish traps etc.
The trees are important for producing good quality charcoal and for firewood. An excellent fuel, it is valued especially for use in baking. A great advantage of this species, in the eyes of firewood dealers, is that it can easily be split.
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