For centuries, indigenous trees have been more than mere witnesses to history; they have been regarded as healers, protectors, and symbols of resilience.
Their barks, leaves, roots, and seeds have long been used as remedies for a wide range of everyday ailments, even before the establishment of pharmacies.
People used to chew bitter roots to treat stomach issues, boil leaves to reduce fevers, and seek protection and spiritual renewal from sacred fig trees.
In today's rapidly changing world, where health challenges are becoming increasingly complex, there is a growing interest in these living pharmacies.
At the forefront of this revival is Njoki Kamau, who owns a tree nursery and has dedicated her life to promoting indigenous trees. When she started six years ago, it was a well-considered decision.
“When I was young, I had always admired the healing properties and cultural significance of these trees. However, growing up, I noticed that indigenous species were disappearing from villages,” she recalls.
During the Covid-19 pandemic, however she saw an opportunity, a demand for herbal medicines which are believed to boost immunity.
“During, and even after the pandemic, people started asking deeper questions,” Njoki recalls. “They wanted to know which trees could help them stay healthy, which ones their grandparents used, and which ones could benefit their children for generations to come.”
At her five-acre tree nursery in Kiambu, Njoki has planted over 50 types of indigenous tree, sourced from the Kenya Forest Service and local sellers.
Among her treasured stock is the neem tree, locally known as mwarubaini. Often called “the tree of forty cures,” it is prized for its bitter bark and potent leaves, traditionally believed to fight malaria, soothe skin infections, and strengthen immunity, making it a cornerstone of herbal medicine.
She also keeps the mugumo tree, the sacred fig deeply revered in Kikuyu culture. Beyond its spiritual significance as a symbol of protection, its leaves ease chest congestion and provide relief during respiratory distress, Njoki explains.
The muthiga, or African olive, stands out for its strong antimicrobial qualities. For generations, its leaves and oil have been used to clean wounds and speed up the healing of cuts and infections.
Another valuable tree in her collection is the muiri (Prunus africana), famed for its medicinal bark. Widely sought in traditional medicine, it is commonly used to manage prostate conditions and promote overall well-being.
Croton species add further diversity to her stock. Their seeds have long been relied on as natural laxatives, while their bark is used in remedies believed to reduce fevers.
Equally important is the African mahogany, whose bark is brewed into decoctions to treat diarrhea and stomach upsets, underscoring its role in supporting digestive health.
Completing her collection are the baobab, acacia, and chestnut—trees with deep roots in healing traditions and cultural heritage, each carrying centuries of wisdom in their branches and bark.
“Covid-19 reminded people that health starts at home. Our indigenous trees are more than just shade or decoration; they are medicine chests,” states Njoki.
She notes that raising indigenous seedlings requires patience and care.
"Some, like mahogany, take many years to mature, while others such as prunus africana and chestnut, adapt quickly.
“It’s not about instant returns. Indigenous trees are slow growers, but they reward patience. You plant for your children and grandchildren.”
Her customers come from a range of backgrounds, including rural and upcountry landowners who are looking for hardy, low-maintenance trees that can thrive with minimal care.
“Schools and public institutions often buy in bulk for afforestation projects. Meanwhile, health-conscious individuals inspired by the rediscovery of traditional remedies during the pandemic also make purchases,” she says.
More people buy trees during the rainy seasons of April and October, when large-scale buyers take hundreds of seedlings at once. In drier months, sales slow to a trickle, but demand never fully disappears.
For anyone wishing to start selling indigenous trees, Njoki emphasises that a large amount of capital is not necessary.
“Assuming one already has land, about Sh20,000 can cover the cost of soil, manure, planting bags and seedlings,” she says.
Not a microwave business
However, she warns: “This is not a microwave business. Indigenous trees do not reward impatience. You must think long-term — decades, even.”
Njoki dreams of creating a dedicated indigenous tree centre where Kenyans can learn about the history, uses and care of each species. She has even started selling “shag bundles” —discounted sets of five indigenous trees — to encourage families to plant them in rural areas.
“We benefit from the trees planted by those who came before us,” she says. “If we don’t plant for future generations, what will they inherit?”
As Kenya modernises, the role of indigenous trees in medicine may change, but their importance remains clear. They remain anchors of heritage, reservoirs of healing and testament to the value of patience.
While Njoki’s nursery thrives on tradition and heritage, science offers a complementary perspective.
The science behind healing trees
Jeremiah Gathirwa, acting deputy director at the Centre for Traditional Medicines and Drug Research at the Kenya Medical Research Institute (Kemri), explains that a tree must contain bioactive compounds — natural chemicals that influence biological processes — to have healing powers.
“These compounds may reduce inflammation, regulate bodily functions, and help the body fight disease. Their healing power isn’t mystical or miraculous; it’s the result of natural chemistry,” says Dr Gathirwa.
Alpha Plants founder Njoki Kamau (left) with her colleague Florence Njeri tends to Warburgia Ugandensis plants at the nursery along Kiambu Road in Kiambu, County on August 16, 2025.
Photo credit: Bonface Bogita | Nation Media Group
To verify whether a tree truly possesses these properties, scientists begin with ethnobotany —the study of how different cultures use and understand plants —to help them identify species that communities believe have healing properties.
"We collect the parts that are traditionally used, such as bark, leaves, or roots, and in the lab, we test plant extracts for biological activity. The extracts are exposed to bacteria, malaria parasites or cultured cells to see if they kill pathogens or improve conditions,” explains Dr Gathirwa.
“For chronic diseases like diabetes, we test whether extracts lower blood sugar. If the results are promising, the research progresses from laboratory tests to animal studies, and eventually some plants reach human clinical trials.”
He further notes that what really matters are the active compounds in plants.
"By isolating and purifying extracts, we can identify the precise molecules responsible for healing. History proves that this approach works: quinine for malaria comes from the bark of the cinchona tree, and artemisinin, which is also used to treat malaria, comes from artemisia annua, a plant that has been used in traditional medicine for centuries.”
Kemri medicinal products
At Kemri, researchers are already making significant progress in turning indigenous knowledge into safe and effective products.
They have developed products including a remedy for hypertension, immune boosters for immunocompromised patients, a treatment for prostate pain, an antimicrobial mouthwash, and an oral, non-hormonal contraceptive almost ready for clinical trials.
Dr Gathirwa says that key ingredients in these remedies include prunus africana, known locally as muiri, and Azadirachta indica, better known as neem. In many cases, multiple plants are combined to enhance their healing effects.
However, he notes that not all plants live up to their traditional uses.
“Some plants that were once believed to cure HIV showed no antiviral activity in controlled studies,' he says. While such remedies may boost immunity or ease symptoms, they do not provide outright cures. This highlights the danger of miracle cure myths —chewing bark or leaves cannot cure cancer or HIV, although such remedies may improve well-being," he says.
Serious risks
While these trees offer potential benefits, Dr Gathirwa warns that using herbs without proper guidance can pose serious risks.
"Some herbs are toxic and can damage organs such as the liver and kidneys. Additionally, certain herbs can interact dangerously with prescribed medications. For example, combining herbal remedies with diabetes drugs can lead to complications.
Dosage is another concern, as taking too much of a plant extract can result in harmful side effects. This is why scientists emphasise the importance of standardisation and careful prescription, he explains.
Many drugs worldwide are derived from plants, and in Kenya, there are efforts to integrate herbal medicine into hospitals.
At Kenyatta National Hospital in Mbagathi, plans are underway to open an alternative medicine pharmacy, offering evidence-based herbal products alongside conventional medications.
However, Dr Gathirwa also highlights the risks of overharvesting.
“The growing demand for medicinal trees threatens to drive some species to extinction," he says. "To address this issue, we are promoting sustainable harvesting practices and establishing botanical gardens in Nairobi, Kirinyaga, and Kisumu."
These gardens, he says will help conserve medicinal plants, provide raw materials for research and serve as living classrooms for future generations.
