10 amazing plants in our MacRitchie Forest

MacRitchie is an awesome place to take a refreshing walk or for runners to enjoy some trail running. This short listicle hopes to highlight some interesting plants that will be easy to spot along the trails. For some plants that don’t flower regularly, it does take a few visits and getting used to the terrain before one can spot a couple of these plants but when you do, it is highly rewarding. Most of these plants can be found only in good primary forests such as those found in parts of MacRitchie.

  1. The leaf litter plant – Agrostistachys borneensis
  2. A wild relative of the mangosteen – Garcinia griffithii
  3. Wild nutmeg – Knema conferta
  4. The petai tree – Parkia speciosa
  5. Wild Ixora – Ixora congesta
  6. The purple Thottea – Thottea grandiflora
  7. Jelutong – Dyera costulata
  8. The keruing belimbing – Dipterocarpus grandiflorus
  9. The common mahang – Macaranga bancana
  10. Kayu Pontianak – Parishia insignis

The leaf litter plant – Agrostistachys borneensis

This plant is a shrub or treelet in the understorey reaching 2 to 3 m tall.

Agrostistachys borneensis

It’s easily recognizable from the long leaves that capture leaf litter in between its leaves. How clever, making its own compost!

Agrostistachys borneensis

As seen in this photo below, the plants send adventitious roots from in between its leaves to the leaf litter. Again, what a clever plant that recycles waste.

Agrostistachys borneensis


A wild relative of the mangosteen – Garcinia griffithii

Wild relatives of agricultural crops are always important to have. Agricultural crops have limited genetic diversity and can be prone to diseases caused by fungi or bacteria. Wild relatives can be used to breed in new traits for disease resistance. Often the source of these wild relatives are found in natural habitats such as primary rainforests. It is interesting that the fruits are ripe at the same time as the Mangosteen season that occurs mainly from July to September.


The tree is quite distinct and you can see the thinner branches sticking out almost perpendicular to the main trunk

Garcinia griffithii

Look closely and you will see the fruits hanging from the branches. The leaves of the genus are opposite and have distinct veins.

Garcinia griffithii

Here’s more info on the Mangosteen we eat which is Garcinia mangostana – referred to as the Queen of Fruits. It is thought that mangosteens we eat originate from a natural hybridisation of two species Garcinia malaccensis and G. hombrioniana.  It is quite surprising that the mangosteen reproduces from seeds which are not fertilised (a phenomenon called apomixis). This means that the mangosteens we eat are genetic clones of the first natural hybrids. But there are variations that occur in the mangosteen so it is plausible that the mangosteen arose from different hybridisations and not from one. One such cultivar is given the cultivar name ‘Mesta’ (so in full it would be Garcinia mangostana ‘Mesta’. You will find it in some mangosteen shops being sold as Japanese mangosteens.  These have a “sharp pointed bottom”  as described in the blog i eat i shoot i post. (Botanical term for such a shape – obovoid). This particular cultivar has very tiny seeds so it feels like it is seedless!

Wild nutmeg – Knema conferta

Sometimes walking along the trails (and not running) allows one to spot things on the forest floor that you would otherwise miss. So stop and observe the leaf litter around and you might just spot something interesting like this wild nutmeg for example. This has a bright red aril (flesh surrounding a seed, mainly to attract dispersers such as birds or bigger animals like monkeys. The flesh of the durian for example is also the aril of the fruit). Unlike the cultivated nutmeg (Myristica fragrans) the aril of Knema conferta covers the entire seed and is not divided into strips.

Horsfieldia sp_2Myristica fragrans

The petai tree – Parkia speciosa

Have you eaten the petai beans? It’s a sort of delicacy usually cooked in sambal with ikan bilis. People who enjoy it have an acquired taste for it – it can be pungent and bitter hence exciting and interesting to eat. Known colloquially as the stink bean, the strong taste and the smell is persistent in the urine a day or two after consumption. It may sound off-putting but take a look at a picture of this dish which uses the beans. The tree is fairly common along the boardwalk along MacRitchie near the water’s edge and the plant flowers and fruits quite frequently. Here is a cluster of legumes (the correct term for the valved fruits of plants that belong to the peanut family Fabaceae).

Parkia speciosa

The knob-like structure on top of the stalk is a cluster of many tiny flowers and each can be pollinated to form the long curvy legumes you see above.  They used to be called “getuk getuk” by children who would use it to knock each others’ heads. Such were the preoccupation before smartphones totally ruined the child’s interaction with nature.

Parkia speciosa

Besides providing children with endless fun, the tree is biologically interesting. As a legume, it would have root nodules that contain bacteria known as rhizobia that help it covert nitrogen gas from the air to a useable form to help plant growth. It’s like the plant has a way of making its own fertilizer. It is also pollinated by bats – see this webpage that has very endearing illustrations and a nice write-up on petais and bats.  If there are no flowers or fruits to indicate the tree, a good way is to look out for the leaves which are twice-pinnate with leaflets which are tiny. Look closer and you will see that at the base of the petioles holding the small leaflets are glands that exude nectar. These attract ants which help defend the plant against herbivores.

Parkia speciosa

Wild Ixora – Ixora congesta

This ixora goes by the common name Jarum Jarum which means bunch of needles, referring to the unopened flowers. See more pictures of this “most conspicuous of our wild ixoras” in the WildSingapore page

Ixora congesta

It certainly brightens the trails along Macritchie with its bright orange flowers. It belongs to the coffee family Rubiaceae and certainly will make a nice ornamental plant or wayside bush.

Ixora congesta


The purple Thottea – Thottea grandiflora

Occasionally, this plant will flower and when it does, these curious looking flowers appear. It is featured also in the Bird Ecology Study Group post on plants in MacRitchie. It’s a close relative of the Dutchman’s pipe vines that have pretty large and similarly coloured flowers – such as Aristolochia grandiflora.

Thottea grandiflora

The plant is larval food for some beautiful butterflies.

Thottea grandiflora_3

And just a couple of years ago a new species of Thottea was discovered right here in Singapore in the Western Catchment forest.

In local webpages, the purple thottea gets featured in articles on MacRitchie, highlighting the fact that you don’t get to see this plant in any other forest type. See these following sites for good write-ups on the flora found in MacRitchie – Nature Watch article rainforest rojak: plants of macritchie nature trail, singapore and Tidechaser’s blogpost Macritchie Reservoir Park.


Jelutong – Dyera costulata

If you see these woody pods on the forest floor, look up an you are certain to see a lofty tree with a crown that shoots above the canopy. To further confirm its identity, the leaves are arranged in whorls of 5 to 8.


It is rather interesting to note that this tree belongs to the periwinkle family and indeed it is the largest plant in that family that includes climbers like the Allamanda, small trees like the Frangipani and bigger ones like the Pulai. The Pulai is a common wayside tree and often flowers synchronously, wafting its perfume along our estates and roads.

The jelutong has been described by E.J.H. Corner as contributing to the fullness of the canopy and commonly rising above the canopy. Along the water’s edge boardwalk in MacRitchie, the one closer to Lornie Road, a few of these magnificent trees can be spotted. Corner (1997), in the Wayside Trees of Malaya, describes the crown being “dense, dome-like and composed of many ascending limbs each of which ends in a conical head of foliage like a minaret.” It’s a handsome tree and not difficult to spot taking into account the fallen pods, whorled leaves and crown.  If you have a binoculars or 200-300mm lens, the pods may still be seen hanging if in season.

Dyera costulata

Dyera costulata


The keruing belimbing – Dipterocarpus grandiflorus

The Malay name keruing is the name given to this genus of timber trees. Belimbing is the qualifying epithet given to this keruing because the calyx tube beneath the wings have 5 prominent ridges making it look like a starfruit (belimbing). The scientific name is also very descriptive with Dipterocarpus literally meaning 2-winged fruit. The specfiic epithet refers to the large flowers of this species. This is an important tree for tropical rainforests. It is a tree of primary rainforests, rarely secondary rainforests and where it is found is an indication of a mature and good quality rainforest in Singapore.

Dipterocarps are very slow growing trees and hence pack their timber densely, making them ideal for making furniture. These trees over may years have been logged for their timber and part of the reason why forests were so economically valuable. Of course primary forests are now cleared to make way for oil palm plantations and other developments.

The 2-winged fruit amongst the leaves of the tree. One can recognise the leaves of the family Dipterocarpaceae generally by the veins that arise from a 45-degree angle from the midrib.

Dipterocarpus grandiflorus

Remember to look up when you see the fruits on the forest floor.  You are likely to see the parent tree and that is a great connection to make.

Dipterocarpus grandiflorus

The flowers are really pretty but the tree only blooms during the mass-flowering and fruiting (also known as masting) of this family of plants (along with other plant species that join in). This occurs usually after a dry spell and for the plant family Dipterocarpaceae happens between a 2-7 year time interval, often correlating to El Niño years.

Dipterocarpus grandiflorus


The common mahang – Macaranga bancana

This plant is quite common throughout our forests and even in disturbed areas.  But along the trails in MacRitchie, one can easily find this ant-plant so looking for it will be easy.  Once you find it, you can marvel at the biology of this plant.  In the photo below starting from the top of the main stem, you will see ants feeding on white food bodies called Beccarian bodies on the lower surface of the leaf like structure called a stipule.  In other plants the stipules function to protect a young bud and fall off after the new leaf forms but here the stipule persists and curves into a dark purplish dome and continue to offer food and shelter to the ants.  In return for the food, it is presumed that the ants offer protection to this plant from herbivores. That’s not all – the ants that live in the hollow of the stem farm scale insects. These scale insects feed on the sap of the plant and exude a honey dew from their behinds and the ants feed on that sugary liquid – this is called cultivation mutualism and a handful of species in the living world carry this out besides humans.

Macaranga bancana


Kayu Pontianak – Parishia insignis

The final one for this list of 10 is a special tree. It is listed as a heritage tree in Singapore and for the one in Bukit Timah Nature Reserve, it has been protected by a lightning conductor cable. This is a relative of the mango trees and is deciduous – meaning it sheds it leaves. In the tropics like Singapore, probably due to a dry spell. The leaflets on its pinnate leaves have been observed to wither red so this tree might just be losing it leaves when the picture was taken.

Parishia insignis