Monday, July 23, 2012

Semakau Landfill

Semakau Landfill is Singapore's only landfill in use, and is also the world's first offshore landfill created entirely from the sea.

However, what many people do not know is that this island still has a natural seashore, with a wide variety of marine animals that is accessible if you participate in an intertidal walk during low spring tide.

The current island is reclaimed from two islands - Pulau Semakau and Pulau Sakeng. The two islands were joined together with a 7.1km rock bund, forming an area of 350 hectares. Previously, the two islands were home to small fishing villages with stilt houses, but the islanders were relocated to the mainland from 1987 to 1991.

During the construction of the landfill, a monitoring programme was established to monitor the impact on the surrounding coral reefs, and silt screens were erected to minimise siltation. As such, the intertidal area of the original Pulau Semakau still harbours very rich biodiversity.

400,000 mangrove seedlings were also planted to replace the forests that were destroyed during the construction.

The landfill started operation on 1 April 1999, it is estimated that it can last till 2045. In 2005, the National Environment Agency (NEA) which manages the landfill decided to open up the island for recreational activities. Since then, several nature groups have organised trips to the island, the most popular trip would be the intertidal trips to see the amazing shore life.

Dos & Don'ts
  1. Contact NEA to find out which nature group is organising trips to Semakau Landfill, as only these groups are allowed to enter the island.
  2. Ensure you reach the jetty (usually Marina South Pier, West Coast Pier or Pasir Panjang Ferry Terminal) on time, or the trip may be delayed, or the boat may leave without you. If you are driving, there is a small carpark at the pier. If you are coming by public transport, check the SBS website for the bus timing.
  3. In case of security checks, everyone has to bring their IC along, and if the children are too young, they will need to bring along their student concession card. Foreigners will have to bring their passport and work permit.
  4. Please wear covered shoes, such as diving booties, water shoes, school shoes or old sport shoes for the shore exploration. No slippers or sandals will be allowed on the shore, as there could be sharp rocks, muddy ground and poisonous organisms. Be prepared to get your shoes wet and muddy, as you will need to cross a seagrass meadow with knee height water, and the forest trail may be waterlogged.
  5. Bring an extra pair of shoes/sandals to change into after the shore exploration, as your original footwear will be wet by then.
  6. Preferably you should be wearing long pants. e.g. light track pants etc. There could be mosquitoes and sandflies.
  7. Please bring insect repellent. Mosquito pads are usually not very useful for such outdoor activities as the mosquitoes and sandflies can be quite aggressive.
  8. Please bring a cap/hat in case of sunny weather, and raincoat/poncho in case of wet weather. Do not use umbrellas, as you will be a walking lightning conductor in the open seashore area. I would also recommend bringing a few plastic bags to keep your electronic products in case it rains.
  9. Even if it rains before the meeting time, do still proceed to meet at the pier, as it may not be raining on the island, or the rain may stop and we can do the walk.
  10. Bring water and some light snacks, as there are no vending machines and canteen vendors on the island.
  11. If you are prone to motion-sickness, remember to bring and take the medication before you board the boat.
  12. Bring a working torch just in case it is still dark or will get dark during the trip.
  13. Bring a camera along, but remember to have a plastic bag to keep it dry in case it rains.

What to Expect at a Semakau Intertidal Walk

The trip usually begins with meeting at the ferry teriminal, and some trips may require you to meet at the jetty as early as 5am in the morning! The boat ride from Marina South Pier to Semakau Landfill takes about an hour, while the boat ride from Pasir Panjang or West Coast may take about 30 min.

If you join a morning trip, you will be required to walk for about 30 min along the road on the island to reach the shore entrance. For afternoon trips, NEA will usually provide transport to the shore entrance. Remember to go to the toilet before the walk, as out on the seashore you will have to survive without toilets for 2 hours.

You will need to walk through a mosquito-infested forest to reach the seashore. This forest is a secondary forest with a mixture of kampong trees, secondary forest plants, freshwater swamp species, and coastal forest plants.

For example, this Aquatic Ginger (Alpinia aquatica) is a freshwater swamp species that is critically endangered in Singapore. Scientists have collected the seeds and saplings from Semakau, and propagated them on mainland Singapore. This plant with delicate flowers is planted in freshwater ponds for ornamental purposes.

The Malay Apple (Syzygium malaccense) is an exotic species common planted in kampongs last time for its juicy fruits and pretty flowers.

Sea Derris (Derris scandens)
The Sea Derris (Derris scandens), a coastal climber, is also critically endangered in Singapore. Sap from the stem is used as a fish poison.

It takes about 5 min to reach the seashore. At the edge of the shore, several coastal plants can be seen. These plants do not grow in areas regularly inundated with sea water, but higher areas that get salt sprays. Hence, they are usually adapted with smooth and glossy leaves that allow salt splashed onto them to be swept away quickly by the wind. Most of them have leathery leaves to retain water, as the sandy or rocky substrate of the shore area does not retain moisture well.

Seashore Pandan (Pandanus odorifer)
The Seashore Pandan (Pandanus odorifer) is one coastal commonly seen on Semakau. The leaves have lots of spines along the edges, and are used for weaving hats and mats, and for thatching. The fruits look somewhat like pineapple fruits. The male flowers yield an essential oil used to scent clothes.

Sea Lime (Ximenia americana)
The Sea Lime (Ximenia americana) is a common coastal shrub/tree which is occasionally a root parasite, even on its own species. The pulp of the fruit is sometimes eaten, though it is mildly poisonous (cyanide).

Sea Hibiscus (Talipariti tiliaceum)
The Sea Hibiscus (Talipariti tiliaceum) is a common coastal tree with heart-shaped leaves. The flowers are yellow, turning orange or red towards the end of the day, and will be shed usually by the next day. The fibre from the bark is used to make ropes and caulk boats.

A little away from the coastal forest are a few mangrove trees. These plants are specially adapted to survive in areas inundated with sea water during high tide. They can either block salt at the root level, or excrete salt through glands on their leaves. Most have roots spreading over a wide area for stability on the soft substrate, and have aerial roots to take in oxygen from the atmosphere as the waterlogged soil lacks air.

Bakau Pasir (Rhizophora stylosa)
Bakau trees (Rhizophora spp.), such as the Bakau Pasir (Rhizophora stylosa), can be found here, and they are easily recognised with their prop roots. These plants can block most of the salt at the root level, and accumulate the salt that got into them in old leaves. The thin and long structures hanging from the trees are the seedlings, not fruits. Mature seedlings are dispersed by water, floating 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. The wood is hard and heavy, and is used for making charcoal. Young seedlings are also edible.

Api-api Putih (Avicennia alba)
Some Api-api Putih saplings (Avicennia alba) have also established themselves here. "Api-api" means "fire-fire" or "firefly" in Malay, as some Avicennia species are noted to attract fireflies. Research indicated that roots of Avicennia species also exclude some salt from entering the plant. Salt glands on the leaves excrete part of the remaining quantity of salt which was not excluded at the roots. The wood of this plant is used as firewood and construction timber. The fruits are cooked and eaten.

Several animals can be found here too.

The Porcelain Fiddler Crab (Uca annulipes) is one of them. A male fiddler crab has an enlarged claw, which it waves the claw to attract the females and to ward off other males. Fiddler crabs feed on detritus, which are basically tiny bits of organic particles, and the male can only feed with its small claw (the big one is too cumbersome) and as it is feeding, it looked like it's playing a fiddle, and hence the common name.  The females have two small equal-sized claws, and thus can eat faster - for a good reason as they need to lay eggs.

There are lots of Zoned Horned Shell (Batillaria zonalis) on the shore. They are like the vacuum cleaners of the shore, feeding on algae and detritus. They are one of the many reasons why visitors should follow the guide's trail, so as to minimise trampling on the many animals living on the shore.

Some of the shells are not occupied by living snails, but by hermit crabs instead, such as these Tidal Hermit Crabs (Diogenes spp.). Unlike the crabs we eat which have a hard shell over their entire bodies, hermit crabs have a long soft abdomen. Only the front part of the hermit crab's body is protected by a hard shell. To protect its soft butt, a hermit crab needs to tuck it into an empty snail shell. As they grow older, they will need to find bigger shells. Interestingly, the genus name of these hermit crabs came from the Greek philosopher, Diogenes of Sinope, who lived in a barrel.

There is a small patch of rocky shore, and some animals can be found here, living among the rocks. Most of them are found hiding under the rocks from the hot sun in the day to prevent dehydration.

Rock Crabs (Leptodius spp.) are common here, and are usually under the rocks. These small crabs have spoon-tipped pincers, believed to help them in scraping off algae from rocks to feed on.

Many Nerites (Nerita spp.) can be found here as well. They feed on the algae on the rocks. Under the hot sun, they will usually keep still and not move much, hiding in shaded areas to avoid dehydration. They have a hard shell to deter predators from eating them. The above is a Chameleon Nerite (Nerita chamaeleon), so named for its variable colours.

sand-sifting star (Archaster typicus)
As you walked further out, you may encounter numerous Sand-sifting Stars (Archaster typicus) on the sand. This is possibly the most common sea star in Singapore, and hence many nature guides also call it the common sea star. It has many common names though, but I personally prefer to call it the sand-sifting sea star, as I thought the name itself tells the story of how the sea star behaves - it sifts among the sand to avoid predation and to forage for detritus to feed on. Unlike most other sea stars, the Sand-sifting Stars have a rather interesting reproduction behaviour - males are often found stacked on top of the females, and the pairing may last for up to 2 months before the eggs and sperm are released into the water. The reproductive organs do not meet, and hence this behaviour is termed "pseudocopulation" - in other words, "fake sex". This behaviour apparently increases the chance of fertilisation though.

Occasionally, the Mangrove Horseshoe Crab (Carcinoscorpius rotundicauda). Horseshoe crabs are very ancient animals, and are said to have been around for more than 400 million years! They have an interesting way of dealing of bacterial infection - their blood will the bacteria and become gel like. Scientists these days use a substance extracted from the blood to test for bacteria on surgical instruments and also some drugs. And scientists from NUS have developed a way to clone this substance, so that we do not have to harvest from the wild as much.

There will be lots of sponges (Phylum Porifera) at the sandy area just before you enter the seagrass meadow. Sponges are simple animals which has lots of tiny holes and a few bigger holes on them. To feed, they suck water through their tiny holes and they will pick out the edible particles. The filtered water will then be pushed out of the big holes. Do you know that bathroom sponges used to be made from sea sponges? Nowadays most sponges were made from petroleum though. Take note that most sea sponges are poisonous and contain tiny glass-like bits though, and are not suitable to be made into bathroom sponges.

You will then need to wade in knee-height water across the seagrass meadow. Seagrasses are flowering plants growing in the sea. They are the only plants that can survive fully submerged in sea water. Seagrasses are very important to the marine ecosystem, as they provide lots of food and hiding places for small animals. Hence, it is something like a nursery ground for many marine species.

Many different types of seaweed can also be found here. Unlike seagrasses, they are algae and do not flower. Also, they do not have proper roots to absorb nutrients from the ground, but have simple structures call "holdfast" to hold onto rocks and other structures. Many animals also feed on seaweed, making them an important part of the ecosystem too. They are a few main groups of seaweed here, grouped according to their colour - the brown algae, the red algae, the green  algae and the blue-green algae (which is actually a bacteria). The above photo shows a Fan Seaweed (Padina sp.) among some Tape Seagrass (Enhalus acoroides).

Sometimes, several species of sea cucumbers can be found in the seagrass meadow or at the sandy areas near its edges.

sandfish sea cucumber (Holothuria scabra)
The Sandfish Sea Cucumber (Holothuria scabra) is one of the most commercially valuable species found in local waters. Often eaten as a delicacy in Chinese restaurants, they are sometimes over-harvested in the areas where they can be found. This species burrows into the sand, using their oral tentacles to gather tiny food particles in the sand. Their sand-like coloration allows them to camouflage with the surrounding sand.

synaptid sea cucumber (Opheodesoma sp.)
This Synaptid Sea Cucumber (Opheodesoma sp.) can grow to over 1.5m long, and is usually found in seagrass meadows. They appear worm-like without tube feet. Instead, they have tiny hook-like structures on their skin, which feel somewhat sticky to the touch and allow the animal to hold on to rocks or seaweed and seagrass. When are usually seen with their oral tentacles extending and lashing around, picking up organic matter from their surroundings.

dragonfish sea cucumber (Stichopus horrens)
The Dragonfish Sea Cucumber (Stichopus horrens) is commonly found in seagrass meadows and adjacent reef flats. It has numerous spiny bumps on its body. While the entire animal is seldom collected for food, natives in the pacific are known to cut it open and its intestines can be eaten raw, sometimes with a bit of lemon. The animal is then returned to the sea, where it will regenerate its lost intestines. The body fluid of this sea cucumbers is also harvested to make air gamat, a traditional Malay tonic used to aid healing, especially for women after delivery.

Away from the seagrass meadow is a reeflat with firm and compact sand, lots of coral fragments and numerous tide pools. The tide pools usually host numerous organisms, as they do not dry out during low tide.

Several giant carpet anemones (Stichodactyla gigantea) can be found in this zone. These sea anemones have sticky tentacles which sting small animals that have gotten too close to them. The tentacles will then transport the prey, acting like a conveyor belt system, to bring it to the centre of the animals where the mouth is located.

The Noble Volute (Cymbiola nobilis), a large sea snail, can also be found here, and sometimes, they can be seen laying eggs - a very good sign indicating that these snails were doing well here! This snail is a fierce predator of clams and other smaller snails. It will embrace its prey with its huge foot to attempt to suffocate it. When the prey eventually opens up to breathe, the volute will feed on it.

Nudibranchs (Clade Nudibranchia)
Several nudibranchs (clade Nudibranchia) can be found on Semakau. The term "nudibranch" means "naked gills", refering to the exposed flower-like gills on the back of most species. They are sea slugs - sea slugs are basically snails with very reduced shells, internal shells or no shells at all. Many nudibranchs are toxic, deriving the toxins from their prey, such as sponges. Like other sea slugs, they are hermaphrodites with both male and female reproductive organs. To mate, they usually get into a "69" position side by side and fertilise each other. The reproductive organs are located behind the head on the right side.

Funeral Nudibranch (Jorunna funebris)
The Funeral Nudibranch (Jorunna funebris) is a common nudibranch found on Semakau. It gets its common name from the black and white coloration. It feeds on a blue sponge (Neopetrosia sp.), and its egg ribbons are white in colour.

Several species of flatworms can also be found here. The above is an Acanthozoon Flatworm (Acanthozoon sp.). It is very common in local waters, but somehow has not been scientifically described yet. Being very flat, it can easily slide into small cracks and gaps among rocks to seek for food and hide from predators. It can also swim by flapping the sides of its body.

Sometimes, octopuses (Order Octopoda) can be seen too. The octopus is said to be one of the smartest invertebrates, and are known to be able to solve puzzles and learn by observation! It is also able to spray a black ink to confuse predators. In addition, octopuses have specialised skin cells which allow they to change their color, opacity, and reflectiveness to blend in with the surrounding and also to communicate with other octopuses.

Hairy Crabs (Pilumnus vespertilio) are very common here as well. The tiny hair on its exoskeleton traps sand and mud, allowing it to blend nicely into its surrounding. This is not the edible Shanghainese Hairy Crab though. Studies in the early 1980s revealed that this crab is sometimes poisonous, probably from a red algae it feeds on. There are also suggestions that this crab also feeds on zoanthids sometimes, which makes it poisonous sometimes too.

Occasionally, the Upside-down Jellyfish (Cassiopea sp.) can be seen. The main photo shows it sideways, while the smaller photo shows how it usually looks like with the tentacles facing upwards. This jellyfish has symbiotic algae which can make food from the sun and pass on some of the nutrition to the former. The algae apparently photosynthesize better with the jellyfish being upside-down.

Moving on towards the reef edge, more hard corals can be seen. Hard Corals (Order Scleractinia), which have a hard calcium carbonate skeleton, mostly live in a colony (though there are solitary ones as well). It's like they live in HDB flats or condominium, and basically each little holes you see on the coral has a little coral polyp living inside. Most of our corals get their colour from symbiotic algae called zooxanthallae, which like the ones in the upside-down jellyfish, provides food for the corals. Most corals also feed on plankton and smaller organic particles. The coral polyps are able to capture food with their tentacles, which contain stingers to paralyse the tiny animals. Coral reefs are basically the huge structures formed by these coral colonies. They are very important to the marine ecosystems, as they provide food and hiding places for animals, and also structure for plants, algae and sessile animals to settle on.

Unlike the hard corals, the various species of Soft Corals (Alcyonacea) do not have the hard calcium carbonate skeleton. There are still colonial animals though, comprising lots of coral animals (aka polyps) connected by a shared tissue. Many of these colonies are known to be able to secrete chemicals to prevent other encrusting organisms from growing over them.

knobbly sea star (Protoreaster nodosus)
The Knobbly Sea Star (Protoreaster nodosus) is one of the bigger sea stars found on Semakau, and some can be more than 35 cm wide! This is perhaps also one of the prettier sea stars, as they occur in various colours, ranging from bright red, orange and pink to dull colours such as brown and beige. They have a hard, calcified body with large nodules on the top surface, which protects them from most predators except fish with sharp and powerful teeth, such as pufferfish and triggerfish. Indeed, every now and then I will see individuals with broken nodules or arms. Despite the big size, this sea star feeds mainly on microorganisms, although it has also been observed to feed on snails, clams, soft corals and sponges. Like most other sea stars, they feed by everting their stomach over their food and digestion takes place externally.

At the reef edge, there is a resident Fluted Giant Clam (Tridacna squamosa). This clam feeds on plankton and tiny organic particles in the water. At the same time, it harbours symbiotic algae in its body. The algae photosynthesize and pass on some of the food to the clam, and in return gain shelter and protection.

On luckier days, you may see Tigertail Seahorses (Hippocampus comes). Interestingly for seahorses, the males are the ones getting pregnant. Female seahorses lay their eggs into the males' brood pouches, and the little seahorses will eventually hatch in the pouches. Seahorses can be really well-camouflaged, especially when they are hiding among the brown seaweeds.

The intertidal walk usually lasts for about 1.5 to 2 hours. After which you will get to wash your feet with the water provided by NEA at the forest entrance. Then, you will be brought on a tour around the landfill on NEA buses, followed by a video presentation on how the landfill operates.

Other Available Nature Trips to Semakau

You can also so bird-watching, sports-fishing and stargazing at Semakau Landfill.

Some of the birds that can be seen there include:

The Great-billed Heron (Ardea sumatrana), which is the tallest bird in Singapore, reaching heights of more than 1m.

Two species of nightjars can be seen here, and the above is the Large-tailed Nightjar (Caprimulgus macrurus). This nocturnal bird feeds on insects.

The Little Tern (Sternula albifrons) can also be found here. It feeds by plunge-diving for fish.

Conserving Pulau Semakau

The landfill on Semakau can only last till about the year 2045, and hence it is important that Singaporeans try to reduce the amount of rubbish generated so as to lengthen its usage. The basic principles of "Reduce, Reuse, Recycle" hence plays an important part - Do reduce the amount of things you use, so as to reduce waste; as far as possible, reuse what you have, so that you do not generate rubbish; and if you cannot reuse any more, recycle them. If everyone practices these, we can be sure that Semakau Landfill can last for a longer period, and perhaps we will not have to create another landfill so soon.

At the same time, it is important that Singaporeans learn more about our marine ecosystems, either through nature walks, books or the Internet, as only when we understand something then we can better protect them. for those who have visited Pulau Semakau, do share your experience with your friends through blogs and photos, so that more people will know about the island. If you have the time, you can volunteer as a guide or in coastal cleanups too. And remember to also feedback about your positive experience on the island through the proper channels, such as news forums etc, so that the authorities will be aware of it.

Sunday, July 15, 2012

Coastal Epiphytes, Ferns & Ground-dwelling Herbs of Singapore

The seashore environment is a very harsh environment for the trees and shrubs growing there. It is usually very dry, due to the land and sea breeze which increases the rate of evaporation. This is more so on rocky and sand shores since the substrates are rather porous. Salt sprays from the sea also have a drying effect on the plants living there. These coastal shrubs and trees, unlike true mangrove plants, are usually found in areas seldom or not inundated such as the back mangroves. Hence, these plants are also called mangrove associates. Many of them can also be found growing in other types of seashore ecosystems, such as sandy or rocky.

In this article, I will share about some of the parasitic plants, epiphytes, ferns and ground-dwelling herbs that I have seen around the coastal areas of Singapore. Note that this guide can only be used in Singapore, as the same species may exhibit a different growth form in other countries.

An epiphyte is a plant that grows upon another plant. Growing on another plant gives the epiphyte better access to sunlight and moisture. A true epiphyte does not derive nutrients from the host plant, unlike parasitic epiphyte which do so. Ferns refer to vascular plants which do not produce seeds but reproduce via spores. In botanical terms, a herb refers to a flowering plant without any persistent woody stem, and the leaves and stem will die down to the soil level at the end of its growing season. Some herbs may have roots or underground stems that grow new shoots for the next growing season, while others die completely and new plants grow from seeds.

This article is divided into the follow sections:

A) True epiphytes (exclude ferns and climbers)
B) Parasitic epiphytes
C) Ferns
D) Ground-dwelling herbs (exclude creepers and grass-like plants)

The species I have included here are definitely not all we have in Singapore - these are just the ones that I have seen. I certainly hope that I can add more species to this page in future.

A) True epiphytes (exclude ferns and climbers)

1. It has a swollen, tuber-like base and opposite leaves.

Baboon's Head (Hydnophytum formicarum)
Baboon's Head (Hydnophytum formicarum) - This epiphyte is critically endangered in Singapore, and got its common name from the swollen stem which resembles a monkey's head. It occurs in mangrove, freshwater swamp and dryland forests. The leaves are leathery and elliptic to broadly lanceolate, oppositely arranged. The small white flowers occur in shallow cup-shaped cavities in thickened nodes on the stem, and the small round or ovoid fruits turn from greenish to orange with maturity. Inside the swollen stem is a labyrinth of tunnels, usually inhabited by ants. It is sometimes planted as an ornamental plant. The stem is used by locals to treat swellings and headache.

2. It is a monocot with green, slightly swollen stems near the base, and fleshy, narrowly oblong-lanceolate leaves.

Pigeon Orchid (Ceraia crumenatum)
Pigeon Orchid (Ceraia crumenatum) - There are several species of epiphytic orchids in the region, but personally I have only seen this species occuring naturally in our mangroves. It bears fragrant white flowers with yellow markings in the middle, and the blooming occurs about 9 days after a sudden drop in temperature, usually due to rain. This common orchid can be found in various forest types, and even on wayside trees in urban areas.

3. It has palmately compound leaves with 4-6 elliptic or somewhat ellilptic leaflets that are not more than 1.5 times as long as broad.

Climbing Umbrella Plant (Schefflera elliptica)
Climbing Umbrella Plant (Schefflera elliptica) - This epiphytic plant occurs either as a straggling shrub or woody climber. I have only seen it growing on mangrove associates in the back mangrove so far, but not on true mangrove trees in Singapore. The flowers occur in clusters with some branches as long as or shorter than the elongated main axis. Each flower is very small. The small fruits usually splitting into 5-6 parts, turning from yellow or orange to black.

B) Parasitic epiphytes

4. It is a mistletoe with elliptic or oblong alternate leaves with glossy upper sides.

Malayan Mistletoe (Dendrophthoe pentandra)
Malayan Mistletoe (Dendrophthoe pentandra) - This common mistletoe grows on various mangrove and coastal shrubs and trees. It also occurs in inland forests. It has small and hairy flowers with very variable colours, ranging from greenish to orange to dark red. The fruits are ovoid and turn red with maturity. They are usually dispersed by birds. The ingested seeds passed through the bird's gut system, and being sticky, they have the tendency to stick to the bird's feathers when it defecates. As the bird rubs against the branches remove the sticky seeds, these seeds will start growing on the branches. This dispersal method is reflected in its name - "mistletoe" is derived from the word "misteltan", and "mistel" is the Anglo-Saxon word for dung, while "tan" means "twig". Hence, "mistletoe" actually means "dung-on-a-twig". Like other mistletoes, the Malayan Mistletoe has special roots (haustoria) which penetrate its host's tissue and draw nutrients from it. A wide variety of animals feed on the leaves, shoots, nectar, flowers and fruits of mistletoes, making them a very important group of plants which can influence the abundance and diversity of animals in the area.

5. It is a mistletoe with ovate opposite leaves with matte upper sides.

Common Chinese Mistletoe (Macrosolen cochinchinensis)
Common Chinese Mistletoe (Macrosolen cochinchinensis) - This common mistletoe grows on various mangrove and coastal shrubs and trees. It also occurs in inland forests. It has small and usually smooth flowers, usually yellow or green but sometimes with reddish markings. The fruits are small, smooth and round, turning from green to yellow and eventually purple with maturity. The glue extracted from the fruit is used to trap birds.

6. It is a mistletoe with obovate or inversely heart-shaped opposite leaves due to a notch at the end. The leaves have matte upper sides.

Pink-flowered Mistletoe (Macrosolen retusus) - Along our shores, this rare mistletoe with pink flowers is only found infesting the Penaga Laut (Calophyllum inophyllum) and Podocarpus (Podocarpus spp.), though further inland it can be found on Salam (Syzygium polyanthum) as well.

7. It is a mistletoe with leathery lanceolate-obovate leaves with more than 3 main veins arranged in a fan-shaped pattern. The stem is green.

Oval-leaved Mistletoe (Viscum ovalifolium) - This uncommon mistletoe grows on various mangrove and coastal shrubs and trees. It also occurs in inland forests. The small flowers are greenish or yellow in colour, while the small round fruits range from yellowish-green to brownish to red.

C) Ferns

8. It is a fern with its fronds divided into 2 main dichotomous lobes which are further divided into numerous unequal lobes.

Bua Cek (Dipteris conjugata)
Bua Cek (Dipteris conjugata) - In Singapore, this critically endangered fern is usually found growing on cliff faces in coastal areas. Younger plants have fewer but more rounded lobes. In the region, they can be found growing in mountain clearings at much higher altitudes. It is sometimes planted as an ornamental plant. The roots are believed to have some traditional medicinal uses in the region.

9. It is a fern with a rosette of long and leathery leaf blades at the top.

Bird's-nest Fern (Asplenium nidus)
Bird's-nest Fern (Asplenium nidus) - This common epiphytic fern got its common name from its resemblance to bird's nest (with some imagination). It can be seen growing on trees in our forests and in urban areas. The spores are held in narrow strips (sori) on the undersides of the fronds. The rosette of leaves traps dead leaves, resulting in a spongy humus that traps rain water. This rain water is also used by other epiphytes growing nearby. It is commonly planted as an ornamental plant.

10. It is a fern with 2 distinct types of fronds - erect fan-like fronds and drooping antler-like fronds.

Staghorn Fern (Platycerium coronarium)
Staghorn Fern (Platycerium coronarium) - This epiphytic fern is common grown as an ornamental plant on wayside trees. It can also be found occuring naturally in our forests. The dangling fertile leaves are divided dichotomously, growing up to 2m long or more, with the spores on shortly stalked, semi-circular to deeply heart-shaped lobes. The erect fan-like fronds trap dead leaves and moisture, providing nutrients for the plant itself and other epiphtyes that may be growing on it.

11. It is a fern with 2 distinct types of fronds - the smaller oak leaf-like nest fronds, and long fertile fronds with numerous blade-like lobes on both sides (feather-like shape).

Oak Leaf Ferns (Drynaria spp.)
Oak Leaf Ferns (Drynaria spp.) - Two species of very similar Oak Leaf Ferns are recorded from Singapore - Drynaria quercifolia and Drynaria sparsisora. I am unable to differentiate them as yet. Oak Leaf Ferns are commonly seen growing on trees in our forests and roadsides. The long foliage leaves are usually stiff and leathery. The sori are small and numerous, occuring in irregular rows at the junction of the veins. The roots are used to treat eye infection. It is also planted for ornamental purposes.

12. It is a fern with many of its fronds deeply lobed on both sides of the midrib, resulting in several pointed tips.

Paku Wanggi (Phymatosorus scolopendria)
Paku Wanggi (Phymatosorus scolopendria) - This epiphytic fern is fairly common in Singapore, occuring in the forests and roadsides as well. It has a greenish, creeping rhizome with dark brown scales. The sori occur in one to three irregular rows on either side of the midrib, extending onto the lobes. The leaves contain a fragrance, coumarin, that can be used to scent clothes and coconut oil. The rhizome is used by locals to treat gecko bites and to accelerate childbirth.

13. It is a fern with narrow and long, glossy fronds, with a midrib that is grooved above and strongly raised below.

Pyrrosia longifolia
Pyrrosia longifolia - This common epiphytic fern also occurs in various forest types and on roadside trees. It has long, creeping rhizomes and leathery leaves with a smooth surface, while the lower surface is covered with greyish, star-shaped hairs. The small and round sori cover the lower surface of the leaves in the upper part in irregular rows between the midrib and the leaf edge. This plant is used by locals to ease labour pain during childbirth.

14. It is a fern with elongated lanceolate fronds that are gradually tapered towards both the base and tip. The midrib is distinct on the upper surface, but usually less distinct on the lower surface.

Tape Fern (Vittaria elongata)
Tape Fern (Vittaria elongata) - This common epiphytic fern occurs in lowland forests, including mangrove, and may even grow on rocks, especially those in shaded areas. The sori are found in a deep groove near he margin, which somewhat curl towards the lower surface at maturity. It is sometimes planted for ornamental purposes.

15. It is a fern with round and fleshy scale-like leaves sterile leaves and longer, ribbon-like fertile leaves.

Dragon's Scale Fern (Pyrrosia piloselloides)
Dragon's Scale Fern (Pyrrosia piloselloides) - This fern is commonly found growing on trees in parks, roadsides and forests. The sori are arranged in a broad band along the edge of the leaf. This plant is used by locals to treat rashes and headaches.

16. It is a fern with somewhat triangular compound leaves and hairy rhizomes.

Rabbit's Foot Fern (Davallia divaricata)
Rabbit's Foot Fern (Davallia divaricata) - This epiphytic fern is very common in Singapore, and is found growing on trees in various habitats. It got its common name from the hairy rhizome, which resembles a rabbit's foot with some imagination. The lobes of sterile leaflets are elliptic and entire, at most slightly serrated, while the lobes of fertile leaflets are elliptic-oblong, deeply lobed with jagged edges. The sori occur on the tip of each vein.

17. It is a fern with reddish new fronds. Sterile compound leaves have green, smooth and glossy elliptic leaflets, while fertile fronds have narrowly linear leaflets covered with sporangia on the undersides.

Paku midung (Stenochlaena palustris)
Paku Midung (Stenochlaena palustris) - This ground fern can form extensive cover over the ground or climb up trees. It is commonly found in open areas where there is enough moisture. It also commonly occurs as a climber in the forest. The stem can be made into a durable rope, and young leaves are eaten as a vegetable.

D) Ground-dwelling herbs (exclude creepers and grass-like plants)

18. It has spirally arranged leaves.

Crinum Lily (Crinum asiaticum)
Crinum Lily (Crinum asiaticum) - This nationally critically endangered coastal plant in Singapore has its lanceolate leaves spirally arranged. It has an fleshy underground bulb, and bear white flowers (sometimes with a purplish edge) with purple stamens. The fruits are round and white. Naturally-occuring ones are sometimes found in shaded areas on our shores, though NParks has also replanted many of them in various coastal areas. It is also sometimes planted as an ornamental plant. Traditionally, this poisonous plant is used as a purgative and for treating foot sores.

19. It has palmately or pinnately lobed leaves.

Seashore Bat Lily (Tacca leontopetaloides)
Seashore Bat Lily (Tacca leontopetaloides) - This nationally critically endangered plant is sometimes seen growing in sandy areas at the back mangrove or supralittoral zone of beaches of some of our southern islands. The flowers are greenish, borne on tall stalks with greenish bracts at the top, while the fruits are green and round. Seeds are small and oblong, with several ridges running along the length. This plant is usually dormant for part of the year, and the leaves will dry up. After a few months, new leaves will grow from the round underground tuber. The tubers can be used to make flour, which in turn can be made into a variety of puddings for consumption.

20. It is a shrubby herb and the edges of its alternate leaves are serrated.

Indian Camphorweed (Pluchea indica)
Indian Camphorweed (Pluchea indica) - This shrubby herb occurs at open areas along the coast or back mangroves. It has light purple or whitish composite flowers. The dried fruits are light with tufts of white hair, and are dispersed by wind. The plant contains compounds found to be anti-diabetics, and neutralises the venom of some snakes.

21. It appears shrubby with opposite leaves. Some have spines on the leaves, while others may not.

Sea Holly (Acanthus spp.)
Sea Holly (Acanthus spp.) - Singapore has 3 species of Sea Hollies (Acanthus spp.) in our mangrove forests - Acanthus volubilis, Acanthus ebracteatus and Acanthus ilicifolius. Acanthus volubilis occurs as a bush-like, sprawling herb, or when there are other taller structures around, as a climber. There are no spines on its leaves. The other two species occur as low, sprawling herbs and seldom climb. The leaves in areas exposed to the sun tend to have more spines than the shaded ones, which may even be spineless. More information here.

  • Chong, K. Y., H. T. W. Tan and 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 and 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.
  • Lok, A. F. S. L., W. F. Ang and H. T. W. Tan, 2009. The status and distribution in Singapore of Dipteris conjugata Reinw. (Dipteridaceae). Nature in Singapore, 2: 339-345.
  • Ng, P. K. L. and N. Sivasothi. 1999. A guide to the mangroves of Singapore 1 : the ecosystem and plant diversity. Singapore Science Centre. Singapore. 168 pp.