Rare parasitic plant discovered in Malaysian forest reserve

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Known as fairy lantern, this plant is a parasite that steals all its energy and nutrients from mycorrhizal fungi that live in the soil. Usually hidden underground, it periodically produces a pink flower, with a dome-shaped top – similar to an umbrella – from which three tentacle-like structures extend.

Gim Siew Tan, a naturalist and photographer, discovered the flower in November 2023, while looking through leaves on the forest floor. She posted images of the plant to iNaturalist, a collaborative platform for identifying plants, animals and fungi.

“So beautiful and unique,” ​​he remembers thinking. “Then the question came: ‘What is it?’”

The photos reached Siti Munirah, a botanist at the Malaysian Forestry Research Institute, who said she immediately recognized that it was a species that had not yet been described by science. Ms Tan, Ms Siti Munirah and their colleagues detailed the plant in a study published last month in the journal PhytoKeys, naming it Thismia selangorensis.

Rarity and risk of extinction

After the discovery, made next to a stream in the Sungai Congkak recreational forest, researchers conducted several surveys in nearby areas. So far, they have only found 20 individuals, some of which lived in tree hollows. Given the plant’s rarity and apparently restricted distribution, it should be considered critically endangered, Ms Siti Munirah said.

The plant Thismia selangorensis is a mycoheterotroph, a term used to designate plants that parasitize fungi. There are only about 550 known species of mycoheterotrophs in the world, such as Thismia flavescens, said Vincent Merckx, a biologist at the Naturalis Biodiversity Center in the Netherlands, who was not involved in the study. This number represents a tiny fraction of the estimated 435,000 plant species on Earth.

The fairy lantern’s most striking feature is its umbrella-shaped dome, described as “extraordinarily large,” located at the top of the flower, a structure known as a miter, according to Michal Sochor, a botanist at Palacký University in the Czech Republic.

This shape could help prevent debris or rainwater from getting inside the flower, said Dr. Sochor, who was also not involved in the study. The function of the tentacle-like extensions is still unknown, but they may release chemicals to signal the presence of the flower when it emerges from the leaf litter.

Like many mycoheterotrophs, these newly discovered organisms are difficult to locate. They spend most of their lives underground and only appear on the surface during unpredictable flowering periods.

Sophisticated parasitism

Most plants form a symbiotic relationship with mycorrhizal fungi, a partnership that has existed for approximately 500 million years, since plants began occupying the earth. Plants provide fungi with sugars produced by photosynthesis, while fungi help absorb water and nutrients from the soil.

Mycoheterotrophs bypass this system by appropriating nutrients without offering anything in return. This is only possible because mycorrhizal fungi are connected to other green plants that use solar energy, explains Dr. Merckx. Like many parasites, these plants tend to be highly specialized, typically exploiting only a single species of fungus, whereas most trees associate with dozens of them.

Thismia selangorensis has short, sturdy roots, described by researchers as “coral-like,” in which the fungi likely reside and are manipulated by the plant.

“I like to think she found me.”

When Ms Tan discovered the new species, she was actually looking for mucilaginous fungi, special organisms that can group together, move around and produce stem-like fruiting bodies.

“Spending time looking for mucilaginous fungi taught me to notice the smallest things on the forest floor,” she said, referring to the new plant. “But I like to think she found me.”

There are currently more than 110 known species of the genus Thismia, most of them in tropical regions of Asia and South America, according to Dr. Merckx. New species continue to be described each year, and it is likely that dozens of them are still unknown. The group is not present in Africa or Europe.

A curious case involves Thismia americana, found in 1912 on the edge of a prairie in North America, outside Chicago, thousands of miles from any known close relatives. The delicate, pale plant was harvested for a few years in the same location until a barn was built in the area. Since then, he has never been found again.

How it got there, so far from its other relatives, remains a mystery – as does the exact function and inner workings of the newly discovered flowers, as well as the fungus the plant exploits.