Researchers scale heights to protect rare tree

The tree is 45m tall, but that did not deter a team of researchers from the National Parks Board from scaling the critically endangered Sindora velutina yesterday to harvest its flowers and fruits for research and conservation.

The species has six known mature specimens in Singapore, scattered across two nature reserves. The tree scaled by the team is the tallest and the only one that produces viable offspring, said Ms Choo Le Min, senior researcher at the Singapore Botanic Gardens, which comes under NParks.

Species are critically endangered when there are fewer than 50 mature individuals known.

Ms Choo, who leads the research team, said: "Fresh flowers will show their colour, scent and shape, which give clues to what its pollinators are.

"If the pollinators can travel longer distances and cross-pollinate, genetic mixing can ensure the survivability of the species."

The harvested flowers have a greenish-yellow exterior and the stamen, the pollen-producing reproductive organ, is pink. There is a light and powdery jasmine fragrance.

The fruits of the tree are long and disc-like, covered with thin and slender spines. Green when immature, the fruits will harden and turn brown when they ripen, said Ms Choo.

The species is more commonly found in peninsular Malaysia and Borneo, where the area of primary forests - dense, undisturbed areas that contain a large and diverse number of trees - is greater.

Leaf specimens of Sindora velutina were last documented in 1954. Other herbarium specimens from neighbouring countries were dried flower specimens, which do not provide insight into the colour, scent and pollination biology of the tree, said Ms Choo. There were also no recorded colour photographs of the flower globally.

The tree, which is under the legume family, forms the canopy layer of rainforests and shades the forest undergrowth. Oil extracted from the trunk used to serve lubricating and waterproofing purposes in the past.

Sindora velutina was presumed to be extinct until it was rediscovered in 2019. Ms Choo, who had been studying the Sindora genus as part of a cataloguing project called Flora of Singapore since 2018, had verified the identity of the tree with a co-researcher from the Nanyang Technological University.

Researching and conserving endangered tree species are crucial for a small country such as Singapore to ensure ecological connectivity, said Ms Choo.

"We have to know (the species') distribution, rarity and population trend and which animals disperse their seeds. Every species is important because they are all interconnected - the loss of one species might have cascading effects on the whole ecosystem."

The species is the rarest one under the Sindora genus - a category of plants that are closely related - that can be found in Singapore.

The Republic is home to around 2,100 plant species.