Koyra Upazila, Bangladesh – The Shakbaria river’s low tide has pulled the water back, exposing a wide, slippery mudbank between Suranjan Raptan and the edge of the Sundarbans, the world’s largest tidal mangrove forest.

For most of his life, Suranjan has relied on this forest as his pharmacy. He rises before the sun, crosses into the mangroves in a small boat and walks barefoot through the clay-mud jungle for hours, carrying a knife to cut the leaves, roots and bark he uses to make medicines.

Today, the 40-year-old traditional healer, or kabiraj, has come to borrow his uncle’s boat.

“Uncle, are you home?” he calls from outside the house.

Chapal Raptan, Suranjan’s uncle and a honey collector, is a medium-built man with sharp features.

“Suranjan? Come in and sit,” Chapal Raptan answers, his voice hoarse. “I worked in the rain yesterday; now I have a cold, so I’m resting.”

“Sad news,” Suranjan replies. “Drink hot tea with tulsi leaves and honey. It will help. I won’t sit now; I’m heading to the forest to bring back some plants. I want to take your boat.”

His uncle tells him where to find it.

“Okay, uncle. Rest well. If you feel worse, I’ll send medicine,” Suranjan says as he sets off.

Beyond the courtyard lies the road, then the Shakbaria river, and across it, the Sundarbans.

Suranjan finds the overturned boat and lowers it into the water. Leaves and fruits from the forest have gathered on the muddy bank. His feet sink deep into the sticky mud. He climbs into the boat, dangling his legs over the side to wash them, and the wind pushes him across small waves towards the forest.

Stepping into the Sundarbans, the smell of wet mud and salt fills the air. Mangrove roots twist up from the water like claws. Kingfishers sound sharp notes in the half-light; insects hum and leaves sway in the breeze. Suranjan walks barefoot, saying it allows him to feel the ground and move quietly, and that sandals slip too easily.

“A deer passed here not long ago,” he says, pointing to a small hole in the mud.

“These leaves,” he says at a bush, “boil them when the stomach aches.”

A few steps later, he touches the bark of a tall tree. “Scrape it, mix with water, it helps when the cough won’t go away.”

Then he finds a tall Sundari tree, with dark-green, oval leaves.

“This is the tree that gave the forest its name: Sundarbans. Now it is rare. We are lucky to see it here.”

He remembers a different forest.

“Before Cyclone Aila (in 2009), the forest was so dense that sunlight could not enter. Since then, it has thinned. The forest feels empty.”

The change became particularly noticeable around 2015 or 2016, he says, when sunlight began reaching places that had once been heavily shaded and familiar medicinal plants became harder to find.

Today he is looking for a particular tree. He searched for it the last time he came but could not find it. He worries it has disappeared.

Suranjan has been a kabiraj for 21 years. He learned from his father, who learned from his grandfather. Nothing was written down. He was taught how to identify plants, where to find them, which parts to harvest and how to prepare them – knowledge passed through practice and memory.

Suranjan lives in Koyra, in Khulna district on Bangladesh’s southwestern coast. From his yard, he can see the green canopy of the Sundarbans rising beyond the canal.

Twenty years ago, Suranjan says, scores of patients filled his yard, men and women, children accompanied by mothers or grandparents, people with coughs, fevers, wounds or stomach pain. Some carried bundles of leaves and roots for him to identify. The crowds began to thin about a decade ago. Now he treats a handful within the community.

Part of the change was happening in the forest. Regular cyclones and rising salinity were making some of the medicinal plants he depended on harder to find. But the choices available to villagers were changing, too.

Bangladesh had begun revitalising its community clinic programme in 2009, expanding primary healthcare in rural and hard-to-reach areas. By 2015, about 14,000 community clinics were operating across the country, offering basic health services closer to people’s homes. Alongside them was a vast network of retail drug shops, where medicines were widely available, often without a prescription.

Suranjan watched as younger villagers increasingly turned to clinics, doctors and pharmacies, he says, while many of those who continued to seek help from kabiraj are older or have few affordable alternatives.

Today, Suranjan’s face carries the glow of a new father. Two days ago, his first child, a daughter, was born at her maternal grandparents’ home. Mother and baby are healthy, and the news has spread through the village.

Neighbours stop him as he passes.

“How are the mother and the baby?”

To younger neighbours, he smiles, places a hand over his heart and says, “With your blessings, mother and daughter are healthy.” With elders, he brings his palms together in greeting. Each encounter ends with another blessing for his newborn daughter.

At home, Suranjan lowers himself onto the smooth earthen floor. When someone suggests he sit on a rug, he smiles and refuses.

“One day I will return to this soil,” he says. “It feels special.”

When the conversation turns to payment, he shakes his head.

“I never charged money. People gave me whatever they could, and that was enough. I was never doing it for money.”

A small electric fan stirs the heavy air. Suranjan disappears into the next room and returns with another. Even after a night and morning of relentless rain, the heat clings to the air.

“It wasn’t always like this,” he says. “A few years ago, after rain, the air would turn cool. I’d put on a long-sleeved shirt, sometimes even a thin scarf at night.”

The Sundarbans stretches across 10,000 square kilometres of Bangladesh and India. Its green canopy shelters the Royal Bengal tiger, saltwater crocodiles and more than 300 plant species. Nearly 2.7 million people live in the coastal districts surrounding the forest on the Bangladesh side alone.

For generations, communities here have turned to the forest for food, firewood and medicine. Kabiraj have long provided care in rural areas where formal medical services can be difficult or expensive to access.

Their remedies are made from leaves, roots and bark, and their knowledge has traditionally been passed from one generation to the next. A 2011 study of medicinal plants in Barisal Division found that almost one-third of rural households in the coastal area sought help from kabiraj or similar healers.

Rising seas and repeated cyclones are pushing saltwater further into coastal ecosystems. Between 2017 and 2021, salinity in tidal water rose from 21 to 33 parts per thousand in the pre-monsoon season, while soil salinity increased by 31 percent.

Mangroves are adapted to salt, but tolerance varies by species. The Sundari (Heritiera fomes) is declining. Bain (Avicennia officinalis), an important source of nectar for bees, has stopped flowering in some places. Medicinal plants that kabiraj depend on are also becoming harder to find.

For Suranjan, the evidence is in what is no longer there.

As the tide enters the forest, fiddler crabs move across the mud. He stops beside a tree and carefully cuts a section of bark with his knife.

“Between the wood and the bark there is a layer. If that layer is not hurt, the bark grows back quickly. If it is damaged, the bark takes longer to grow, and sometimes it never grows again, the wound stays.”

When harvesting a vine, he never pulls out the whole plant. He cuts only what he needs so it can grow again.

But careful harvesting cannot protect plants from changes in the water itself.

“Before, during the tide, the forest did not sink completely. The higher ground stayed dry,” he says. “But now the forest goes fully underwater, and because of the saltwater many trees are dying.”

He names species that have become difficult to find: hogla, or Typha, whose fibres are traditionally applied to cuts and burns and whose roots are used in local remedies; and bain, whose bark and leaves are used in traditional medicine and whose flowers provide nectar for bees.

“My father collected more than 100 medicinal plants from different parts of the country and planted them in our garden,” he says. “But because of Cyclone Aila in 2009, saltwater entered and destroyed all our plants; they all died.”

Professor Md Abdur Rahim, chairman of the Department of Genetics and Plant Breeding at Sher-e-Bangla Agricultural University, describes a forest whose botanical balance is shifting.

“Salt is slowly rewriting the forest. The hardy trees may survive, but the plants that heal, the ones kabiraj rely on, are disappearing,” he says. “As salinity rises, the forest changes its face: salt-loving species spread, while the delicate, medicinal ones fade.”

A season without flowers

Nearby, a small tea stall filled with wooden benches stands beside the Shakbaria river. Inside, a television sits silent during the day; villagers gather around it in the evening. The morning rain has left water pooled on the road and clouds hanging low over the river.

Customers drink strong black tea with sugar, sometimes with biscuits.

Suranjan’s uncle, Chapal Raptan, the honey collector, sits on one of the benches.

Asked how much honey he gathered this season, Chapal, having overcome his cold, shakes his head.

“This is the time for bain flowers,” he says. “But this year, not a single bain tree has bloomed. There is no bain honey at all.”

Several men respond at once.

“We have never seen this in our lifetime,” one says as the others agree. “Not a single flower on the bain tree.”

For men who have spent their lives entering the forest, the missing blossom is more than a poor honey harvest. It is an unfamiliar change in a landscape they thought they knew.

Suranjan names other medicinal plants he says are becoming difficult to find around Koyra: neem, ashwagandha and haritaki.

Then he looks down at his hands.

“It is becoming difficult to collect medicinal plants. Since I don’t have all the necessary medicines in my collection, I cannot give patients what they need on time when they come.”

Three houses away from Suranjan lives Deepa Mandol, 32. On the veranda, she sits beside her husband as he takes medicine. Their six-year-old son has just bathed and is waiting to eat.

“Suranjan-da (brother) is the first person I go to when someone is sick in my family – fever, cold, cold-cough or feminine physical problem. If you go to him, he will make medicine,” she says.

Her husband has hepatitis B. Some people use local herbs to ease symptoms such as jaundice or to feel better, but these cannot remove the virus from the body.

The family sits on a wooden khat in the yard. Deepa, barefoot in a pink sari, begins feeding her son rice, fish and potatoes with her hand.

“I do not have money for the doctor in town. The clinic is far. The medicines are expensive. Suranjan-da never charges.”

Clinics and private doctors’ chambers operate in Koyra, but reaching them from settlements near the forest can mean travelling by boat or rickshaw. A private consultation typically costs about 500 to 800 taka ($4-$7), before medicines and transport. Government facilities are cheaper, but residents say waits can be long and medicines are not always available.

A little farther along the road, 80-year-old Suvodra Mondal watches over her goats in the late afternoon. The wind from the Shakbaria river lifts strands of her white hair.

She suffers from joint pain and stomach problems.

“I often have headaches and pain in my knees from arthritis,” she says. “I collect medicine from my nephew, Suranjan Kabiraj. He prepares it with plants, mixes it with honey, and gives it to me. After taking it, I feel some relief.”

She has also sought medical treatment in town.

“I went to see a doctor in the town, but they said treatment would cost a lot of money. My son catches fish in the forest to eat, how could he ever afford that? I take medicine from Suranjan instead. It makes me feel a little better, the pain eases. Sometimes I pay if I have money, sometimes I don’t; he never says anything.”

The scarcity of freshwater adds another burden. Families collect rainwater during the wet season and store it in tanks. During the dry months, Deepa says, people may walk about two kilometres to a freshwater pond, a four-kilometre round trip, to collect drinking water. NGOs have installed desalination systems in some areas, but these too can be distant and require queueing.

“We don’t have freshwater here,” Deepa says. “Everyday life runs on saltwater, for cooking, for bathing, for everything.”

Then she returns to the problem that shapes so many decisions here: money.

“We are poor people. We cannot afford treatment in the city. We have no money for costly medicines. Kabiraj is our hope.”

Several kilometres away, in the Mothbari area of Koyra, rain has turned the paths to sludge.

Shrimp enclosures reflect the grey sky. A narrow path leads towards the home of another kabiraj, with bricks laid through the mud as makeshift stepping stones.

Provat Sarder’s house is small, built from old red brick and wood, with two rooms, a kitchen and a veranda. Inside, the floors are earthen.

Provat is 65, with thinning white hair and a deeply lined face. Wearing a T-shirt and lungi, he speaks slowly in a low voice.

“I have been a kabiraj for 35 years,” he says. “My grandfather was a kabiraj. But I am the last one; nowadays, no one wants to study hard any more.”

His grandfather, Basanta, introduced him to healing when Provat was a teenager. At around 15, he watched him treat a neighbour who had been bitten by a snake. Afterwards, Provat began learning from him.

Snakebite is a medical emergency. Experts interviewed for this story stressed that anyone who may have been bitten by a venomous snake should be taken urgently to an appropriate medical facility rather than relying on traditional treatment.

The kabiraj interviewed for this story said families often seek them out first. Some kabiraj now advise patients to reach a hospital quickly, but such referrals remain uncommon.

Inside his house, Provat brings out a bag of dried medicinal plants.

His hands are rough and darkened by years of work, but his fingers move slowly as he unwraps each packet. White paper crackles beneath them. He pauses from time to time, careful not to tear the wrapping or let a leaf fall.

“This is all I have left,” he says. “Once I had three times as many. But I have to collect them from different districts of Bangladesh, sometimes from a nursery. The plants are rare now. So I keep what little I have, using them sparingly, afraid to waste even a leaf.”

He lifts a dried green leaf from a small box.

“This is Sundari,” he says. “Not the tree, but the leaf. It eases stomach pain. I used to find it everywhere, just a short walk away. Now I must go deep into the forest, and even then I cannot be sure I will find it.”

Once, Provat grew many of the ingredients he needed in his own yard. Now, he says, he has to travel farther or buy plants from nurseries.

He returns the leaf to its wrapping with care, as if returning it to a treasure chest.

About a kilometre away, Mamata Bachar, 59, sits on a roadside bench. She remembers being bitten on the hand by a snake while asleep on the veranda of her house.

“My body began to burn,” she recalls. “My head hurt so badly I wanted to tear my hair out.”

Her eldest son ran to call Provat.

“My hand swelled up,” Mamata says. “Provat kabiraj first rubbed mustard oil on the bite. Then, right in front of me, he prepared medicine, mixing crushed leaves with honey before giving it to me to eat. Slowly, the pain eased. Later he gave me more medicine, and little by little, I recovered.”

Her account reflects her own experience; it is not evidence that traditional remedies can safely treat venomous snakebite.

For Provat, the anxiety now is not only about individual plants but the shrinking collection on which his work depends.

“I am afraid,” he whispers. “Not for myself, but for the people who come to me. They arrive with pain, with fevers, with wounds, hoping I can help. What will happen when I have nothing left to give them? When the forest no longer answers and the medicine is gone, what will they do?”

The environmental changes affecting medicinal plants are also reshaping daily life around the Sundarbans.

Research in coastal Bangladesh has associated high sodium exposure through drinking water with increased blood pressure, while other studies have investigated possible effects of saline water exposure on skin and reproductive health.

Provat remembers when nearby ponds tasted different.

“The water used to be sweet,” he says. “We could drink from the pond, wash ourselves in it, feel refreshed. Now it is salty. It stings our skin. And the plants that grew near the pond, the ones we used for medicine, they are gone.”

He looks towards the ground.

“Everything is connected,” he says.

The losses extend beyond the plants themselves. The United Nations climate body, the UNFCCC, describes cultural heritage, local knowledge, identity and biodiversity among the “non-economic losses” climate change can cause, harms that cannot readily be expressed in financial terms.

A 2025 study of the Sundarbans reported widespread perceptions of wildlife decline and the disappearance of traditional medicinal plants.

Even counting the healers themselves can be difficult.

Asked separately how many kabiraj once worked around Koyra, Provat and Suranjan both begin counting from memory.

Provat names the healers he remembers: his teacher, Basanta Kabiraj; Sukumar Mandal in a nearby neighbourhood; Nalen Biswas in Madhyapara; others in surrounding communities.

“Now, none of them are alive,” he says. “Their disciples are no longer in this work. They have gone to other professions.”

About 10 kilometres away, Suranjan makes his own count.

“In my father’s time, there were maybe eight to 10 here,” he says. “Now? Perhaps three. Old are gone. I do not know a single young kabiraj. One is my nephew, just practising with me.”

There are no local written records charting the decline. Traditionally, the knowledge itself was rarely documented: elders taught children and healers taught apprentices orally.

Now younger people are moving into other occupations, while the plants on which the knowledge depends are becoming less familiar and less available.

“We are the last generation,” Suranjan says.

A 2026 study in Barguna district found that 18.5 percent of kabiraj surveyed were over 60, while 81.5 percent had learned through family inheritance.

Dr Sarder Nasir Uddin, principal scientific officer at the Bangladesh National Herbarium, has seen that rupture in his own family.

“My grandfather was also a kabiraj in the Barguna district. As a child, I used to see many people flocking for treatment; Dada (grandfather) would listen attentively and give the necessary medicine. But my father stopped practising and went into a different profession. My grandfather had several disciples, but now I don’t know where they are.”

Uddin remembers medicinal plants growing around ordinary homes during his childhood.

“In the village of my childhood, we saw medicinal plants like the tulsi tree (Ocimum tenuiflorum) and the basak tree (Justicia adhatoda) in every kitchen yard in front of or beside the house,” he says.

“They used them when someone got a normal fever, cold, or cough. But now they are no longer visible. Due to the easy availability of modern medicines, people have lost interest in these forest remedies.”

Uddin has spent years documenting traditional uses of mangrove plants and investigating their bioactivity.

“The Sundarbans is a treasure chest of medicinal plants,” he says. “But we are losing them before we fully understand their potential.”

Further pharmacological research, he argues, could identify medically useful compounds in species that are disappearing.

“Some researchers are trying. But it is a race against time. The healers are growing old. The plants are disappearing. And there is no systematic effort to preserve what is being lost.”

Professor Rahim sees the decline of plants such as Sundari and golpata as cultural as well as ecological.

“That tree is more than wood and leaves, it is the identity of the forest itself. But Sundari is dying. The disease that eats it is not just an ecological problem, it is a cultural wound.”

“And it is not only Sundari,” he says. “The golpata, the Nipa palm, is woven into the lives of coastal families. Its leaves cover their roofs, its fibres shape their households, its presence is stitched into their culture.”

The danger, Uddin says, is not simply that modern medicine will replace traditional remedies. Knowledge accumulated over generations may disappear before researchers can establish what scientific, historical or cultural value it holds.

“Every time a kabiraj dies, a library burns.”

Rain beats steadily against the tin roof of Provat’s house. Puddles shine in the grey light. Drops cling to the leaves outside his door and fall one after another. Wind blows fine rain onto the veranda, where Provat sits on a mat.

Asked what he imagines for the future, he is silent for a long time.

“I will be dead,” he says finally. “Or too old to walk. And the plants, the ones that are still here now, they may also be dead. Or they may be changed. Changed by the salt. Changed so much that they are no longer useful.”

He looks outside.

“So what will happen? The people will go to the clinic. They will pay for medicine. They will wait in line. They will do what they can. And they will forget that there was ever another way.”

He pauses.

“That is what hurts the most,” he says. “Not that I am losing my work. But that they are losing their memory. One day, no one will remember that there was a plant called ‘thankuni’ or ‘basak’. No one will remember that it could heal a wound. It will be as if it never existed.”

Back at Suranjan’s house, the medicinal garden his father once filled with more than 100 plants has almost gone. Suranjan is trying to grow another.

Beside the house, young plants rise from plastic pots filled with soil brought in from elsewhere. A 2,000-litre (528-gallon) tank stores rainwater for the family to drink and, when there is enough, for the plants. During the dry season, he rations it carefully.

He points to a tulsi plant. Several branches have died. The remaining leaves are small and wrinkled.

Suranjan takes one between his fingers and crushes it.

“Look at the smell, the smell is much weaker than in other areas. Its medicinal effect is also less potent.”

Last summer, several of his plants died. He blames the salinity.

“I found some seeds from a neighbour. I planted them. Now it’s the rainy season, so the salt is a little less in these areas, and these plants may last longer until before summer, or I’ll have to take care of them by collecting freshwater from a long distance.”

He crouches beside one of the pots and presses the damp soil gently around a seedling. For a moment he stands looking at it.

Then the rain begins again.