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Hope blooms for an ‘extinct’ Sri Lankan tree that reemerged under threat

  • The rediscovery of a Sri Lankan legume tree (Crudia zeylanica) in 2019 was rare good news of a species still surviving despite being declared extinct years earlier.
  • But that tree is now threatened by a road project, prompting an outcry from conservationists, the general public, and even Buddhist monks, who anointed it in a ritual meant to discourage anyone from cutting it down.
  • There’s still hope for the species, however, with botanists finding C. zeylanica specimens in six other locations and managing to germinate its seeds in a lab.
  • The botanist responsible for the tree’s rediscovery, Himesh Dilruwan Jayasinghe, also rediscovered two other plant species declared extinct in Sri Lanka’s 2012 red list; an update to the red list is due in the next few weeks.

COLOMBO — Scientists have been writing obituaries for the Sri Lankan legume tree since 1982, when the last known specimen of this endemic plant died. In 2006 Sri Lanka declared the species, Crudia zeylanica, officially extinct in that year’s edition of the national red list of threatened species, and emphasized it again in the latest edition, in 2012.

Then, in 2019, C. zeylanica rose from the dead: a group of young researchers found a solitary specimen growing in the wild in the Daraluwa area of western Sri Lanka. But the land it sits on is in the path of a planned expressway. In February this year authorities began clearing the area for the project, and it was only thanks to the intervention of Devanee Jayathilaka, a regional officer with the Forest Department, that the C. zeylanica tree was spared from being uprooted.

Standing tall: the Crudia zeylanica tree at Daraluwa in western Sri Lanka. Image courtesy of Bhathiya Gopallawa.

There’s since been a popular outcry from scientists, religious figures, and the general public to save the tree. Among those leading the campaign is Siril Wijesundara, research professor of plant taxonomy and conservation at the National Institute of Fundamental Studies. He’s also a co-author of that very first obituary published in 1982, which described the last known tree of the species that grew at the Royal Botanical Gardens, Peradeniya. And he’s not keen to have to declare the species extinct yet again.

He says the tree should be allowed to remain where it stands, and that the proposed elevated road should either go around it or be built higher — both costly options for the developers. There’s no guarantee, Wijesundara says, that the tree will survive being uprooted and transplanted elsewhere, as the Road Development Authority has suggested.

Crudia zeylanica is a habitat specialist tree,” Wijesundara tells Mongabay. “This individual tree is old and can have a complex root system that would hamper relocation attempts.”

Any attempt at relocation will require significant pruning; once relocated, the tree may never grow back to its original size, Wijesundara says. It currently measures 10 meters (33 feet) high, with a girth of 1.2 meters (4 feet), and has taken 70 to 80 years to grow this way and to take root, experts say.

The cause of saving the tree has been embraced by a wide swath of Sri Lankan society. Citizens have staged protests to demand its protection, and a group of Buddhist monks ordained the tree — a ritual that makes it taboo to cut down.

An experiment by botanists at the Royal Botanical Gardens, Peradeniya, in central Sri Lanka has shown that Crudia zeylanica seeds have a 70-80% of germination success. The plant still needs a specialized habitat closer to streams for optimal growth. Image courtesy of the Royal Botanical Gardens, Peradeniya.

Hope for the species

But even if this tree is lost, the species isn’t. Since the discovery of the Daraluwa specimen, botanists have found other individuals of the species elsewhere.

“So far we have found C. zeylanica trees from six other locations where some trees appear to be much older than the first,” Achala Attanayake, deputy director of the Royal Botanical Gardens, told Mongabay.

Some of these were found as a result of a field survey carried out by the Sri Lankan Department of National Botanical Gardens, while others were discovered through tips offered by amateur botanists, Attanayake says. One C. zeylanica specimen grows on a riverbank in Henarathgoda Botanical Garden (HBG), about 30 kilometers (17 miles) from the Daraluwa tree.

Himesh Dilruwan Jayasinghe rediscovered three out of five plants listed as extinct in the 2006 and 2012 national red lists, including Crudia zeylanica. He started out as a civil engineer with an interest in butterflies, before cultivating an interest in local flora. Image courtesy of Chathura Udayanga.

Scientists from the Royal Botanical Gardens have also collected seeds from the tree in Daraluwa to try and cultivate them as part of a species recovery plan.

“It is encouraging that 70-80% of the seeds have successfully germinated,” Attanayake says.

He says most of the known wild specimens, like the HBG tree, are found close to streams that inundate only occasionally, indicating a specific habitat in order to thrive.

C. zeylanica trees would have existed in these locations for long, but we have not been observant enough,” says Himesh Dilruwan Jayasinghe, one of the scientists who in 2019 discovered the tree found in Daraluwa.

That discovery came as Jayasinghe and his team were carrying out an environmental impact assessment on the areas earmarked for the construction of the central expressway. “Identifying a tree cannot be done overnight. It needs patience,” he says, adding they had to wait for months until the tree began bearing flowers and fruits to be certain about the identification.

The December 1982 edition of Loris, the journal of the Wildlife and Nature Protection Society of Sri Lanka, carried an article on ‘Ex-situ conservation of Woody Plant Species in Sri Lanka,’ authored by Savitri Gunatilleke and Siril Wijesundara that details what was then thought to be the last Crudia zeylanica plant in Sri Lanka.

Bringing species back from the dead

The case of Crudia zeylanica is not the only one of a plant species being declared extinct, only to reemerge years later. Sri Lanka’s 2012 red list names five plants in the “extinct” category, but three of them have been rediscovered since the publication, including C. zeylanica. In each case, Jayasinghe has been responsible for leading the rediscoveries.

The 2012 red list also identifies 177 plant species as being “critically endangered/possibly extinct,” mainly because they hadn’t been observed for a long period of time and there was no targeted research into them. Jayasinghe’s field work since then has yielded observations of dozens of these plants, which should qualify them for an improved conservation status with the next update of the red list in the next few weeks.

A civil engineer by training, Jayasinghe is also an expert on butterflies and founded the Sri Lanka Butterfly Conservation Society. A project surveying butterfly larval plants led to his interest in studying flora.

Wijesundara, who first announced Crudia zeylanica’s demise, is the lead expert on the flora section of the upcoming red list update. He says he’s happy to see rigorous scientific research and fieldwork bring back more species prematurely declared extinct. The outcry over the Daraluwa tree, he says, “raises the need for study and conservation of flora in a big way and has resulted in rediscovering what we thought were extinct.”



Banner image of a Crudia zeylanica tree courtesy of Himesh Dilruwan Jayasinghe. Experts are waiting for the tree to bear flowers to conclusively remove the tree from the country’s list of extinct plants. 

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