GANGTOK,: Researchers here have discovered two extremely elusive fungus feeding orchids at the bamboo groves of Rey Khola near Gangtok and have urged authorities concerned for conservation of this particular habitat as these sensitive flowering plants cannot be grown elsewhere.
The two elusive fungus feeding orchids discovered are Gastrodia sikkimensis - named after Sikkim - and Didymoplexiella siamensis.
Madhusudhan Khanal, a PhD scholar from the Department of Botany, Sikkim University and project coordinator- G.B.Pant National Institute, North East regional centre along with the team of researchers, assistant professor and scientists from Sikkim University, G.B.Pant National Institute of Himalayan Environment and Botanical Survey of India had made the stunning discovery.
“This group of orchids are extremely rare and are often called as holomycotrophic or mycoheterotrophic orchids. Holomycotrophic orchids are unique as they are leafless and lack chlorophyll. These orchids parasitize compatible soil fungus and survive stealing carbon from them. They remain underground most of the time with their buried tuberous rhizome and sprouts and blooms only after adequate rainfall. This group of orchids have a very short flowering period of less than 15 days,” said Khanal.
Gastrodia sikkimensis is an orchid species new to science and named after the green State of Sikkim from where it was discovered. The new species Gastrodia sikkimensis have been published in a reputed plant journal ‘Phytotaxa’.
Khanal shared that during June 2022, he had come across the unique fruiting bodies at the bamboo groves of Rey, about 30 minutes’ drive from Gangtok, but could not identify them as there were no flowers. Following continuous monitoring, the orchid was finally observed in flowering during May 2023.
“The plants are so small that it barely grows more than 5 cm tall and as they grow on dense rotten bamboo litter, spotting becomes even more difficult. The flowers are also tiny and almost closed which opens only through a minute pore at its apex. Even after rigorous tracing only 28 individuals were seen growing in its natural habitat. It was also surprising to see the plant height increasing many fold during fruiting”, said Khanal.
The other orchid discovered at the Rey bamboo grove, Didymoplexiella siamensis is another rare holomycotrophic orchid discovered from the region. It has been reported as a new generic record for India and was published in a reputed plant journal ‘Feddes Repertorium’.
The species was observed growing from the dense leaf litter in dark corner of the bamboo forest.
“These orchids were initially observed in buds in which 32 individuals in a single subpopulation were located but due to abrupt rise of temperature of the region during its flowering period during the second week of June 2023, majority of the juvenile individuals dessicated and I could only trace 12 individuals in flowering. The plants grow much taller reaching up to 15 cm tall and have tiny pinkish flowers borne at its apex. The flowers are wide opening with a mild fruity aroma,” said Khanal.
We have also discovered a similar species Gastrodia bambu from the bamboo groves of Kalimpong, West Bengal which was reported as a new record for India, added Khala. He informed that the species was totally deceiving with a brownish colour flowered that looked like a rotten mushroom, and only 7 individuals were found growing on decaying leaf litter.
Threat to rare orchids with habitat loss
According to the researcher, these orchids are extremely sensitive to anthropogenic disturbance and cannot be grown elsewhere as they are fully dependent on soil fungus of a particular habitat like the Rey Khola bamboo groves.
“Bamboo groves of Rey Khola, Gangtok, Sikkim are an ecologically rich landscape. Due to immense diversity of compatible soil fungus the area shows a luxuriant growth of holomycotrophic orchids,” said Khanal.
He pointed out the immense threat to these elusive and sensitive orchids as Ray Khola is a regular picnic spot for people of Gangtok and adjoining areas with the riverside offering a great location for hangouts on holidays.
“This influx of people is causing immense threat to these extremely sensitive orchids. Bamboos around the area are being cut down and plastic waste has considerably increased within the habitat. Also people have started collecting leaf litter from the bamboo forest floor which is detrimental to the growth of holomycotrohic orchids,” said Khanal.
“In our recent visit to check the species we found many individuals trampled by humans. Terrestrial orchids like Didymoplexis pallens, Acanthephippium striatum, Dienia ophrydis, Crepidium acuminatum and Tropidia angulosa also inhabit the area. If the anthropogenic disturbance is not controlled there is a high chance that these rare plant treasures would be completely lost in the upcoming time,” expressed the researcher.