Oct 25, 2006

Seagrasses of Singapore

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Several fascinating species of seagrasses grow on our shores. Here's a quick introduction to all the species that can be found in Singapore.Tape seagrass (Enhalus acoroides) is the longest seagrass found on our shores. The leaf blade is 1-2cm wide and can be 1.5m long! Pulau Semakau has vast tracts of Tape seagrass meadows that stretch for kilometres!

Male flowers of the Tape seagrass are tiny (see the small white bits?). They form in a bract that grows at the base of the plant. During a bloom of Tape seagrass, little 'rafts' of male flowers are often seen floating on the water. They look like little bits of styrofoam!

Female flowers are large and emerge on long coiled stalks. The pale yellowish petals last only for a day or so. Often, all that is seen are the V-shaped bracts. Soon, the large fruit develops. It is a hairy capsule that holds several seeds. The seeds are said to be edible and are eaten by some coastal dwellers. The raw seeds are said to taste like chestnuts.

There are several species of Halophila seagrasses. Some have oval leaves and thus called Spoon seagrasses. The various species of oval-shaped Halophila are difficult to differentiate in the field, so all of them are generally referred to as Halophila ovalis complex. These seagrasses are the most commonly encountered on many of our shores.

The beautiful Fern seagrass (Halophila spinulosa) is made up of many little leaflets. Usually a bright green, sometimes with a bluish tint, this seagrass is widespread on Chek Jawa.

Singapore is home to the delicate Beccarri's seagrass (Halophila beccarrii). The tiny leaves of this seagrass emerges in a rosette of 4-5 leaves. Elsewhere in the world, this seagrass is considered rare. But it is quite commonly seen on Chek Jawa.

There is a large patch of ribbon seagrass (Cymodocea rotundata) on Chek Jawa. This elegant seagrass is narrower and not as long as Tape seagrass.
Needle seagrass (Halodule sp.) is long, narrow and well, needle-like. On Chek Jawa they are lush and long. Elsewhere, they may be much shorter.

Sickle seagrass (Thalassia hemprichii) is indeed sickle-shaped. A lush meadow of this seagrass grows on Labrador, the last on our mainland.

Sickle seagrass has little flowers with curly 'whiskers'.

Syringodium isoetifolium is a strange seagrass. Its leaf blade is cylindrical, like plastic tubing! It is commonly seen (so far) only on Pulau Semakau.

Our job for Seagrass Watch is to look out for all these wonderful plants on our shores. And to monitor their growth.

I can't wait to start!

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