So it was a real delight when Chay Hoon spotted this tree today at Pulau Ubin!According to the "Guide to the Mangroves of Singapore" by Prof Peter Ng and N. Sivasothi, in Singapore there are only a few trees at the hot springs (Kampong Unum) of Pulau Tekong. Trees at Kampong Melayu (Pulau Ubin) and Kampong Mandai Kechil have died or been destroyed with development.
The tree is difficult to distinguish from other Sonneratia species without the fruit. So it's fantastic to see the fruits today! In Sonneratia ovata, the sepals clasp the berry. While in the more commonly seen Perepat (Sonneratia alba), the sepals spread out forming a star-like shape behind the berry.
I noticed there were a lot of tiny ants all over the fruits.
Here's a developing berry within the clasping sepals. 
And then, there was this thing. I'm not sure what happened here. Is the fruit supposed to fall off while the sepals remain stuck on the branch? I don't really know.The tree was short and was in the middle of a whole bunch of other plants. So it's not possible to see its trunk or roots.
But here's a look at its leaves.What a great find today! And thanks to Chay Hoon's eagle eyes for spotting it!
References
- Hsuan Keng, S.C. Chin and H. T. W. Tan. 1990, The Concise Flora of Singapore: Gymnosperms and Dicotyledons. Singapore University Press. 222 pp.
- Davison, G.W. H. and P. K. L. Ng and Ho Hua Chew, 2008. The Singapore Red Data Book: Threatened plants and animals of Singapore. Nature Society (Singapore). 285 pp.
- Tomlinson, P. B., 1986. The Botany of Mangroves Cambridge University Press. USA. 419 pp.
- Giesen, Wim and Stephan Wulffraat, Max Zieren and Liesbeth Scholten. 2006. Mangrove Guidebook for Southeast Asia (PDF online downloadable). RAP publication 2006/07 Food and Agriculture Organization of the United Nations Regional Office for Asia and the Pacific Bangkok.