Guwahati: A rare fungus-feeding terrestrial orchid in Sikkim which has been found at a picnic site in Sikkim might get lost if disturbance is not stopped.
Madhusudhan Khanal, a research scholar from the Department of Botany Sikkim University along with the researchers, professors and scientists from Sikkim University, G.B.Pant National Institute of Himalayan Environment and Botanical Survey of India have found a very rare terrestrial orchid Didymoplexiella siamensis from the bamboo forest of Rey Valley, Gangtok. Sikkim marks a new generic addition to the orchid wealth of India.
The new report for India was published in a reputed plant journal – Feddes Repertorium.
“These orchids are terrestrial holomycotrophs i.e., they don’t have chlorophyll hence feeds of a compatible fungus. In fact, it can also be said that these orchids parasitize the fungus devouring carbon from it, hence calling them holomycoparasites would be the correct term. These terrestrial orchids are very rare as they grow only in certain habitats with the compatible fungus present and bloom for a very short time. All the year round they are underground with their buried rhizome and sprouts and flowers rapidly after adequate rainfall. Due to their extremely short phenological timeframe, they are often missed,” Madhusudhan Khanal told EastMojo.
“Holomycotrophs are the mushrooms of the Orchid world,” says Madhusudan.
“During June 2023, while checking the bamboo groves at Rey Valley for orchids, I stumbled upon some slender shoots with apical buds growing from the pile of rotten bamboo leaf litter, initially I thought of as Didymoplexis, another common holomycotrophic orchid present in the area. On the subsequent visit, I saw them elongated much longer than Didymoplexis which made me doubtful about the species. Due to the abrupt rise in temperature during the subsequent visit most of the juvenile flowering individuals had dessicated. I could only notice 12 individuals in flowering from a single subpopulation,” he said.
He said the plants were much taller with smaller pinkish flowers and the flowers had a mild fruity aroma. Detailed observation under a stereomicroscope and consultation with relevant literature resulted in its identification as Didymoplexiella siamensis, an orchid genera new to India. Fruit setting was later observed in only 4 individuals. It is currently known from China (including Taiwan), Thailand, Laos, Cambodia, Vietnam, and Japan.
Didymoplexiella siamensis doesn’t have chlorophyll, it stays underground throughout life except for the flowering period and feeds of a fungus. “Alongside it should be the only holomycotroph from India with a sweet aroma. Other holomycotrophic orchids like Gastrodia, lecanorchis, and galeola have foul aromas,” he said.
“Rey khola is like a picnic site with constant anthropogenic activities and these species grow at the bamboo groves beside the river. Recent visit at Rey was much disheartening as most of the bamboo has been cut down and plastic litter has increased considerably,” he said.
Madhusudan expressed concern that people have also started collecting leaf litter from the area which is detrimental for these elusive orchids. “We have tried to inspire the locals to conserve their rare wealth and we have got a positive response from them,” he said.
“Intervention from the forest department or any national organization would be the only plausible option for their conservation. If the disturbance is overlooked there is a big probability that we will lose these jewels in the near future,” he said.
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