Tengar (Ceriops tagal)

The Tengar (Ceriops tagal) is a nationally vulnerable species of mangrove tree from the family Rhizophoraceae. I do not quite agree with the current conservation status though, as I have noticed that it is a lot less common than the endangered C. zippeliana.


This species is usually found on the landward edge of mangrove forests, especially in areas inundated by spring tides with well-drained soils. Personally, I have seen it at various mangrove forests, such as Pulau Semakau, Pulau Ubin, Lim Chu Kang and Sungei Buloh Wetland Reserve.


Interestingly, on Semakau it can also be found towards the seaward side.


The trunk is grey or brown in colour, and mature plants may have small stilt roots at the base of the trunk. The roots radiating from the tree somewhat loop above and below ground, forming knee roots. These roots help the plant breathe air, which is scarce in the waterlogged soil. The roots spread over a wide area to help stabilise the tree on the unstable ground. Like other mangrove species from the family Rhizophoraceae, C. zippeliana relies on its roots to exclude salt from entering the plant through a process called ultrafiltration.


It has simple, opposite leaves with rounded tips. The new leaf buds are laterally compressed, appearing like a blade, and are protected by prominent stipules which fall off as the leaves mature.


The small flowers are white and turn brown quickly, and have 5 thick and claw-like sepals.


Vivipary is observed in this plant, as with the other mangrove species from the family Rhizophoraceae. This is a condition whereby the embryo grows and break through the seed coat and the fruit wall while still attached to the parent plant. Hence, the long and green structures seen hanging from the trees are seedlings, and only the brown structures at the top of the green structures are the fruits. C. tagal fruit is smooth and plain, unlike C. zippeliana fruit which has a textured pattern. The seedling has a white/yellow collar, unlike the latter which has a red collar. The seedlings usually occur hanging downwards, unlike the latter extending is various directions, possibly due to the longer fruit stalk. The hypocotyl is warty and angular.

The seedling is dispersed by water. It floats horizontally for a few weeks, during which the root (lower part) will absorb water and become heavier, eventually causing the seedling to tip and float vertically. As the tide goes down, the vertically-oriented seedling will sink into the mud or other suitable substrates. Most of the seedlings, however, end up being washed ashore or eaten by animals.

The wood is very hard, strong, durable, and salt-resistant, and is good for house construction and other heavy usage. When I visited one of the Malaysian mangrove forests, I was also told that it makes good firewood, and is also used to make charcoal. A dye from the wood and bark is used to dye batik.

References

• Chong, K. Y., H. T. W. Tan & R. T. Corlett, 2009. A Checklist of the Total Vascular Plant Flora of Singapore: Native, Naturalised and Cultivated Species. Raffles Museum of Biodiversity Research, National University of Singapore. Singapore. 273 pp.
• Giesen, W., S. Wulffraat, M. Zieren & L. Scholten. 2006. Mangrove guidebook for Southeast Asia. RAP Publication 2006/07. FAO Regional Office for Asia and the Pacific & Wetlands International. Bangkok. 769 pp.
• Ng, P. K. L., and N. Sivasothi. 1999. A guide to the mangroves of Singapore 1 : the ecosystem & plant diversity. Singapore Science Centre. Singapore. 168 pp.