The Kusum tree, also known as Schleichera oleosa, is an important deciduous tree species indigenous to parts of India, Bangladesh, Nepal and Sri Lanka. It plays a significant ecological and economic role throughout its native range.
Description of the Kusum Tree (Schleichera oleosa)
The Kusum tree is easily identified by its distinctive bark and leaves. Its bark is greyish-brown and peels in irregular flakes as the tree ages. The leaves are pinnate, growing in alternate clusters up to 30 cm long. Each leaf contains 11–21 narrow oval leaflets.
Bark
The bark of the mature tree is its most distinguishing feature. It develops an uneven, flaky texture that helps distinguish it from other similar tree species. Traditionally, the bark is harvested for use in rope-making due to its strength and durability.
Leaves
The compound leaves provide shade beneath the canopy of a mature tree. Each leaf grows up to 30 cm long, with 11–21 individual leaflets attached along the central vein. The leaves turn yellowish before dropping during the dry season.
Flowers and Fruit
Small, greenish-yellow flowers bloom in drooping panicle clusters. By fall, these develop into round brown fruits approximately 1cm wide. Each fruit contains a single seed and the fully mature seeds are edible by humans and wildlife.
Distribution of the Kusum Tree
The natural range of the kusum tree spans several South Asian countries. It is most commonly found growing in tropical, dry deciduous forests throughout India, Bangladesh, Nepal, Pakistan and Sri Lanka.
Native Regions
Within its native area, the kusum tree favors well-draining soils and thrives in regions with variable rainfall between 700 and 2500 mm annually. Some of the major forest types it is found in include:
- Southern Deccan peninsular dry deciduous forests
- Northeast India has semi-evergreen and moist deciduous forests
- Terai-Duar savanna and grasslands
- Sri Lankan dry zone: dry-mixed evergreen forests
Ideal Growing Conditions
They grow well at low to mid-elevations from sea level up to 1000 m above sea level. It requires hot temperatures year-round and tolerates seasonal drought. Areas with concentrated rainfall between June and September suit it best.
Distribution Map
A distribution map shows the native range of the kusum tree encompasses much of the Indian subcontinent as well as portions of East Nepal, Bhutan and Sri Lanka. It is less common towards the northern extremes of its range.
Uses of the Kusum Tree
The kusum tree has a long history of diverse uses among the native communities where it grows. Several parts of the tree are utilized for different commercial and domestic applications.
Kusum oil
Kusum oil is derived from the seeds of the kusum tree (Schleichera oleosa), known for its various health and cosmetic benefits.
Lac and Wax
Lac and wax are secreted from the bark of the tree. These two natural resins have been used traditionally to waterproof wood, ceramic and fabrics. The wax is also used in wood polishes while lac acts as a natural varnish.
Rope and Baskets
The hardy bark of the kusum tree lends itself well to rope-making and basket weaving. The strong fibers are twisted or woven into ropes, bags and other products that are durable in wet conditions.
Timber
The golden-hued termite-resistant wood of the tree makes it valuable for construction, flooring and furniture. It is a popular material for building homes, boats, carts and agricultural implements.
Medicine
Various plant parts have uses in indigenous Ayurvedic and herbal medicine systems. The bark, young leaves and fruits exhibit anti-microbial and anti-diabetic properties useful for treating skin diseases and fevers.
Fodder and Food
Leaves and young shoots provide fodder for livestock during droughts. Fruits from the kusum tree are eaten by people and wildlife alike, providing vitamins and minerals to the diet.
Ecological Role of the Kusum Tree
Beyond its direct uses, the kusum tree fulfills several important ecological functions within its native forests.
Habitat and Food Source
The tree hosts a variety of native birds, mammals and insects within its branches. Fruit bats, lemurs and langurs all consume kusum tree fruits and disperse their seeds.
Soil Improvement
Nitrogen-fixing nodules form on kusum tree roots, allowing it to draw atmospheric nitrogen into the ground. This naturally fertilizes the soil underneath its canopy.
Erosion Control
A dense network of kusum tree roots binds soil particles together. This helps stabilize slopes and riverbanks, reducing erosion during heavy rainfall events.
Microclimate Regulation
The year-round foliage of kusum trees provides shade and humidity. Their cooling canopy creates a more temperate microclimate beneath, allowing other species to survive harsh summers.
Biodiversity Hub
By maintaining moisture and habitat, stands of kusum trees support a rich diversity of plant and animal life in tropical dry forest ecosystems.
Growing Kusum Trees
While these trees are well-adapted to conditions in tropical dry forests, some care is needed when establishing them outside their natural range or in cultivation.
Propagation
They can be grown from fresh seed. It is best to scarify and soak seeds for 24 hours before sowing indoors. Transplant the seedlings once they reach 30 cm tall.
Planting Conditions
They thrive in full sun but can handle partial shade. Select a site with well-draining soil and ample room for roots to spread. Plant at the start of rainy season.
Watering
During the first two years, water deeply once or twice Kusum Tree weekly, depending on rainfall. Established trees are drought tolerant but may drop leaves during prolonged dry spells.
Fertilization
Apply a 2-3 cm layer of well-rotted compost or manure in a 1 m-diameter ring around the tree trunk in spring and summer. This supplies nutrients for growth.
Pruning
Prune only if necessary to maintain a strong structure, remove dead wood or control the size and shape of the tree. Most pruning wounds will self-seal without treatment.
Pests and Diseases
Crown gall, leaf folders and occasional fungal spots are minor issues. Generally, these trees are robust and resistant to the most common threats in warm tropical zones.
Benefits of Kusum Tree Products
The various products derived from kusum trees have enduring value due to their durability and natural attributes.
Wax and Lac Production
Kusum wax and lac are highly water-resistant and form strong, flexible coatings. Traditionally used to weatherproof ropes, wood and ceramics, they maintain effectiveness for decades without degrading.
Medicinal Properties
Research has shown kusum bark, leaf and fruit extracts exhibit anti-diabetic activity, likely due to their antioxidant phenolic compounds. Local healers also use these parts to treat skin infections, fevers and digestion issues.
Nutritious Fruits
At maturity, the round kusum fruits turn yellow-brown and slightly tart in flavor. Each fruit holds a single seed that provides a tasty snack, rich in vitamin C, niacin, calcium and dietary fiber. Ripe fruits are good for livestock and wildlife diets as well during food shortages.
Versatile Timber
Durable even when exposed to moisture, kusum wood maintains strength and integrity for decades without treatment. It is resistant to termite damage, making it an excellent choice for flooring, doors, furniture, boatbuilding and house construction. The wood grain and finish also enhance its aesthetic appeal indoors.
Rope and Structures
Strong ropes and durable thatch or wood structures last for many years when constructed from kusum bark fiber. These products stand up impressively to wear, weathering action and moisture damage over time in tropical climates.
Sustainability of Kusum Trees
While kusum trees are well-adapted to thrive in harsh environments, populations face threats that require active conservation measures.
Habitat Loss
Widespread clearing of forests for agriculture, grazing and development has reduced natural kusum tree habitat across Asia in recent decades.
Overexploitation
Unsustainable rates of bark stripping from wild trees for rope and thatch overstress populations. Branch-lopping further damages trees’ ability to regenerate.
Limited Cultivation
Despite their versatile uses, these trees remain underutilized outside natural forests and are not cultivated on the scale of other timber species. More rural propagation is needed.
Climate Change Impacts
Rising temperatures and longer droughts predicted under climate change may stress kusum trees in parts of their native range without sufficient moisture.
Conservation Efforts
Some reserves protect remaining kusum forest patches. Agroforestry projects encourage interplanting trees with crops on farms. Community management of non-protected trees also shows promise.
Sustainable Harvesting
Regulating bark collection and branch lopping to allow trees to fully recover between harvests ensures populations remain healthy. Rotational felling maintains timber supplies long-term.
Continued research, cultivation initiatives, education and sustainable use practices can help maintain resilient tree populations for future generations. With wise stewardship, these adaptive trees will keep providing invaluable products and habitat.