By Soham Kacker
At first glance, a pitcher plant looks fairly unremarkable. Broad, strappy leaves form a glossy rosette, which grows out from a central point – they could easily be mistaken for just another houseplant. Yet, on closer inspection your eye is drawn down the bright green vein along a leaf, to its tip from where sprouts a long, vining tendril. After curving upwards and looping a few times, this thin appendage gives rise to one of the most uniquely-adapted leaves of the plant kingdom: a perfect liquid-filled pitcher with a lid, which seems to levitate above its waxy mouth. This wonder of evolutionary refinement has developed to perfect one function – to attract, trap, and digest insect prey. In India, a sole species represents this enigmatic group – the Khasi pitcher plant, or Nepenthes khasiana.
The Khasi plant is endemic to the Khasi hills of Meghalaya, growing in poor soil as a climber. Photo: Nishanth Srinivas.
As its name suggests, the Khasi pitcher plant is endemic to the Khasi hills of Meghalaya, but has also been reported from scattered populations in the Garo and Jaintia ranges. It grows as a rambling climber in soils with poor nutrient content – this unlikely habitat has given rise to a suite of adaptations to enable the plant to obtain nutrients from other living sources. The plant produces two different kinds of pitchers, each specialised for a different kind of prey. Lower pitchers are rounder, wider, and have a broader lip – intended to trap crawling prey. Upper pitchers produced from leaves higher up in the canopy develop slim cavities with a thin lip to trap flying insects. This adaptation ensures the plant maximises its chances of getting a meal.
One may wonder, how do these pitchers actually attract insects? While other species of pitcher plants have evolved tempting fragrances or sugary secretions, N. khasiana relies on a bioluminescent lip, which glows blue under ultraviolet light. Botanically called a peristome, this structure acts as a landing pad for curious insects. Material biologists have studied its surface and determined that its waxy surface with rows of minute inward-curving ridges is highly slippery. Once an insect lands, it quickly loses its foothold and falls into the trap. The pitcher itself is filled with a liquid, which is specialised for nutrient extraction. Carbonic acid and enzymes called chitinases work to break down the tough exoskeleton of the plant’s insect capture, and the walls of the pitcher are specialised to absorb soluble nutrients.
The Khasi pitcher plant’s unique form and local specificity have made it central to the traditions, medical practices, and livelihoods of the local communities, which share its habitat. The liquid from unopened pitchers is prized as a tonic, sometimes used as eyedrops, and together with the leaves and roots is used to treat a variety of ailments from leprosy to diabetes. Today, what threatens the Khasi pitcher plant most is its unsustainable collection from the wild for sale in the ornamental horticulture industry. Local people often collect and sell it as a means of earning a living from the rising demand.
The Khasi pitcher plant has two kinds of pitchers, one specialised to trap crawling prey, and one to trap flying insects, to maximise chances of getting a meal, and thus nutrition. Photo: Nishanth Srinivas.
The case of the Khasi pitcher plant poses a larger conservation dilemma – is it reasonable to expect local communities to give up earning a living from a natural resource, which they have used for generations? And if not, what does that mean for the future of India’s only pitcher plant species? In recent decades universities, government conservation agencies and private laboratories have worked with communities to cultivate the plants at scale in order to ease pressure on wild stocks. Although pitcher plants have seen a 40 per cent decline in population over the past 30 years, the trend is beginning to reverse. However, it is still listed as ‘endangered’ by the IUCN owing to other threats such as habitat loss. Perhaps the key to successful conservation lies in integrating the interests of people and plants – in the case of N. khasiana, the pitcher is definitely half-full!
Devi, Soibam Purnima et al. ‘Nepenthes khasiana Hook f., an endangered tropical pitcher plant of India’. Indian Journal of Traditional Knowledge, Vol. 18, No. 1, January 2019, pp. 68–75, ISSN (online): 0975-1068.
Konwar, Parthapratim, et al. ‘Identifying conservation priority areas and predicting the climate change impact on the future habitats of endangered Nepenthes khasiana Hook f. utilising ecological niche modelling’. Journal for Nature Conservation, Vol. 74, 2023, p. 126436, https://doi.org/10.1016/j.jnc.2023.126436.
Soham Kacker is passionate about plants and has apprenticed at the Auroville Botanical Gardens and the Aravalli Biodiversity Park. Currently based in the UK, he is a Master’s student at the University of Oxford, focusing on plant ecology and conservation.