07 December 2008

Some plants of Semakau

The rare Seashore Bat Lily (Tacca leontopetaloides) was one of the key objectives of this trip.This plant was first discovered by Joseph Lai during the Semakau mangrove survey conducted by Zeehan Jaafar and Loh Tse Lynn in 2005. This plant is listed as Critically Endangered in the 2008 Red List of threatened plants of Singapore.

This means there are fewer than 50 mature individuals, or more than 50 mature individuals but less than 250 with some evidence of decline or fragmentation. According to the Singapore Red Data book, in Singapore, it is restricted to a few populations in Pulau Semakau and Pulau Pawai (just opposite Pulau Semakau). It is rare here because of the loss of its preferred habitat, i.e., dappled shaded areas immediately behind sandy beaches. Fortunately, some plants propagated from Singapore stock have been planted at Bukit Batok Park.JC Chua and Yan Wei are very excited by the find. And James spots some flowering. We are very careful not to stomp on any seedlings as we take the photos.

The mangrove experts were also taking photos of common mangrove trees and plants. Most of these are well represented on Pulau Semakau, with quite a lot of trees of Rhizophora stylosa which is not as commonly encountered in our other mangroves and is listed as Vulnerable on the 2008 Red List. Alas, we couldn't find the Avicennia marina which was recorded during the 2005 Semakau survey, or any of the special mangrove trees that JC Chua had been sharing about finding on Pulau Pawai.But we did see several of the 'Pong pong' trees (Cerebera sp.). We're not sure if these are the special C. manghas as the flowers had a light yellow centre, and not a pink one. C. manghas is listed as Critically Endangered in the Red List of threatened plants of Singapore.It was nice to see a large bush of the Portia tree (Thespesia populnea). It resembles the more abundant Sea hibiscus (Hibiscus tiliceaus) with very similarly shaped leaves and flowers.Here is Thespesia populnea on the left and Hibiscus tiliaceaus on the right. Here's more on how to tell these two plants apart on the Mangroves of Singapore online guide.

We spent a lot of time on the the plants on the high shores as the tide was very high! Pulau Semakau has magnificent stands of the Seashore pandan (Pandanus odoratissimus) and lots of Ximenia americana which has oval fruits. Chay Hoon found a funny caterpillar on a leaf of one of these plants.

But we saw lots of plants that we have no idea about. An odd climbing plant.This climber with large leaves, and pretty purple flowers.A delicate plant dotted with little star-shaped flowers and bell shaped fruits.Several large bushes of this plant with a constellation of pretty white flowers.
This strange plant with hairy pods.A tree that looks like Sea almond (of which there were a lot) but with a different kind of fruit.And a tree with bright yellow flowers.

Pulau Semakau used to be inhabited by a kampung. So there might be some surviving ornamental bushes or trees that might have grown wild.

There sure is a lot to find out, especially for botanically-challenged shore explorers more used to looking at intertidal flora and fauna!


  1. Hi, I am able to give you all the names of the plants listed in this blog.

    Very good collection of rare coastal plants on P. Semakau!

    John (now visiting Beijing and Shanghai as an Invited Speaker)

  2. The unidentified flowers shown here are from top to bottom:
    1. Cassythia filiformis
    2. Canavalia maritima
    3. Caesalpinia bonduc
    4. Guettarda speciosa
    5. peltophorum pterocarpum

    for any further clarifications please contact me at:
    Dr. A. Waheed

  3. Thank you Dr A. Waheed for these identifications! It is very much appreciated!

  4. sorry,
    in my earlier comment I ommitted three plants. In order they should be:
    3. Canavalia maritima
    4. Colubrina asiatica
    5. premna serratifolia

    Dr. A. Waheed



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