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.
