Pterocarpus marsupium, locally known as Gammalu, is one of Sri Lanka's most medicinally significant deciduous trees. Native to the Indian subcontinent and Sri Lanka, it grows across dry and intermediate forests, often reaching considerable heights with a broad, spreading canopy. Its prominence spans centuries of Ayurvedic practice, traditional carpentry, and forest ecology — making it far more than just another native hardwood.
What makes Gammalu significant in Ayurveda?
In the classical Ayurvedic tradition, few trees hold the standing of Pterocarpus marsupium. The heartwood and bark are the most therapeutically prized parts. When the heartwood is soaked overnight in water, it releases bioactive compounds — primarily pterostilbene and epicatechin — that are associated with supporting healthy blood sugar metabolism. This preparation, sometimes sold as a "kino cup" or wooden cup, has been used in South Asian households for generations as a daily wellness ritual for people managing Type 2 diabetes.
The tree's reddish exudate, commonly called kino resin, has documented astringent properties. Traditional practitioners apply it in preparations aimed at wound healing, treating diarrhoea, and managing inflammatory conditions. Gammalu is formally recognised as part of Sri Lanka's catalogue of Ayurvedic medicinal plants, alongside species such as Acacia chundra.
What are the main medicinal uses of Pterocarpus marsupium?
The range of traditional applications attributed to Gammalu is broad and well-documented in Ayurvedic literature:
- Blood glucose regulation: Heartwood preparations are widely used as a supportive measure for managing elevated blood sugar, and modern pharmacological studies have explored the role of epicatechin in beta-cell regeneration in the pancreas.
- Wound healing: Kino resin is used topically to clean wounds and reduce inflammation.
- Digestive health: Bark decoctions are used in managing diarrhoea and dysentery due to their astringent action.
- Anti-inflammatory action: Various parts of the tree are incorporated in classical Ayurvedic formulations addressing joint inflammation and chronic conditions.
- Oral health: Powdered bark has been used in traditional dental preparations for its astringent and antimicrobial qualities.
Anyone using Gammalu-based preparations alongside conventional medication should consult a qualified practitioner, particularly given its effects on blood glucose levels.
Where does Gammalu grow in Sri Lanka?
Pterocarpus marsupium favours the dry zone and intermediate climatic zones of Sri Lanka. It is found naturally in forests across the North Central Province and parts of the Southern and Sabaragamuwa zones. The tree thrives in well-drained, rocky or laterite soils and is well-adapted to seasonal drought conditions.
In protected landscapes, Gammalu trees can be encountered within the boundaries of Wilpattu National Park, one of Sri Lanka's oldest and largest national parks, where the dry mixed evergreen forest supports a wide range of hardwood species. Similarly, isolated specimens appear in and around Udawalawe National Park. These forest ecosystems depend on species like Gammalu for their structural canopy and the wildlife they shelter.
What does the Gammalu tree look like?
Gammalu is a large deciduous tree that can grow to around 30 metres in favourable conditions. The bark is grey to brownish and develops a rough, scaly texture on mature specimens. Leaves are pinnately compound, and the tree produces pale yellow flowers — characteristic of the Fabaceae (legume) family — typically between February and April, before or just after the dry season flush of new leaves.
The seed pods are circular and winged, resembling a small purse — which likely gives the species its Latin name, marsupium, meaning pouch. The reddish kino resin that oozes from wounds in the bark is immediately identifiable and distinguishes Gammalu from superficially similar forest trees.
How is Gammalu timber used?
Beyond its medicinal value, Gammalu is prized as a structural and furniture timber. The heartwood is dark reddish-brown, dense, and highly resistant to moisture and insect damage. Historically, it was used in the construction of temples, traditional furniture, and fine carpentry. Sri Lankan craftsmen have long valued its workability and durability, particularly in heavy-duty applications where longevity under humid tropical conditions is essential.
Today, as natural populations face pressure from habitat loss and selective extraction, Gammalu is increasingly recognised as a species requiring sustainable management. Its ecological role — providing canopy cover, supporting soil health through nitrogen fixation, and offering food for forest fauna — extends well beyond human utility.
Is Gammalu related to other Ayurvedic trees?
Pterocarpus marsupium belongs to the Fabaceae family, which includes many economically and medicinally important trees across South and Southeast Asia. Within Sri Lanka's Ayurvedic pharmacopoeia, it is often discussed alongside Pongamia pinnata (Karanda), another native tree whose bark, seeds, and oil feature prominently in traditional medicine. These species together represent the depth of botanical knowledge embedded in Sri Lankan Ayurvedic practice.
Other resin-producing and hardwood trees in the regional tradition share some applications, but Gammalu's specific association with blood sugar management and its distinctive kino exudate make it botanically and therapeutically unique in this group.
How can I use Gammalu responsibly?
The simplest traditional preparation involves placing a small section of Gammalu heartwood in a glass or cup of water overnight and drinking the infused water in the morning. Commercially, this method is facilitated by purpose-made wooden cups turned from the heartwood — the water absorbs the bioactive compounds through extended contact with the wood grain.
Kino resin is typically available in dried form from Ayurvedic pharmacies and practitioners across Sri Lanka. As with all herbal preparations, consistency and dosage matter. Those managing diabetes or blood sugar conditions should treat Gammalu preparations as a complementary measure rather than a replacement for prescribed medical care, and always discuss use with a healthcare provider.
