Family: Malvaceae
Common name: Silk cotton tree, Kapok, Kapok tree, Java cotton, White Silk Cotton Tree, Kabu-Kabu, Java kapok, Silk-cotton, Samauma
Silk Cotton Tree is an imposing, tall, and majestic tree renowned for its size, impressive foliage, and thick seedpods that produce cotton-like fiber. They are native to Central and South America, but have been introduced to many countries in Asia and Africa.
Tree Characteristics
Mature Silk Cotton Trees can grow over 50-70 meters tall in the wild, stabilized by buttress roots that spread horizontally along the ground. Older the tree, the bigger and more wide spread its roots.
Bark is thick, brown, and relatively smooth, sometimes with thorns all along the trunk, when the tree is small. These trunks can reach a diameter of 3 meters, often more, due to the buttress roots that add to the girth.
Silk Cotton Trees look very beautiful since they have large expansive roots at the base from which a straight trunk goes up, and then opens up into a wide canopy of horizontally spreading branches. In fact, they look like the very definition of a tree that we see in textbooks!
Leaves of the Silk Cotton Tree are palmately compound with 5-8 leaflets extending from the center of the leaf where the petiole is attached. They are dark green and glossy, 15-30 cm in diameter, with smooth margins. These trees are deciduous and can shed leaves during fall and winter.
Though the Silk Cotton Trees do not flower every year, it is quite a spectacle when they do, since the tree is covered with large, showy, pale yellow or green flowers with a slightly darker center. They are 6-8 cm in diameter with soft, waxy petals and prominent yellow-tipped stamens.
These flowers appear in large clusters at the tip of the branches, emitting a light, but not very pleasant fragrance that attracts large pollinators like bats and birds that play a major role in pollination.
Silk Cotton Tree fruits are large, elongated capsules that are borne in clusters, hanging down in bunches pendulous structures. They are 30-40 cm long, initially green, turning brown or gray as they mature.
The fruit is filled with numerous black seeds surrounded by white cotton fibers that are thickly packed inside.
The fruits can mature and open up while they are on the tree, revealing the cotton fibers inside, or they can fall to the ground and then open up. These fibers can stay afloat and also hold up multiple times in weight and hence they are used in padding, insulation, making mattresses, pillows, and so on.
Gardening Tips
Silk Cotton Trees are not for small gardens since these majestic trees need a large area to grow and spread over many, many years.
They need good sunlight and well-drained soil, though they can tolerate poor soil conditions once the tree is established in the soil.
These trees grow well in tropical and subtropical regions where the climate is warm year-round. Silk Cotton Trees should be watered regularly when they are small.
Fertilization can be done once in a few months to ensure that the soil around the tree has the necessary nutrients.
Since Silk Cotton Trees have beautifully rounded canopies, pruning is usually not needed, unless you want to control the size of the tree.
Uses of Silk Cotton Tree
Silk Cotton Tree has many medicinal uses in the treatment of wounds, cough, asthma, skin allergies, diarrhoea, conjunctivitis, fever, headache, heart problems, and many other ailments. Most parts of the plant, like bark, root, stems, leaves, flowers, and fruits, have medicinal uses in the treatment of a variety of ailments in traditional herbal medicine.
Seeds are used for making cottonseed oil, which is used as a lubricant and for soap manufacturing. The wood of the tree is light and used for making cheap furniture, crates, utensils, canoes, matches, farm implements, etc.
Fiber obtained from the fruits is known for its springiness, resilience, and resistance to vermin. Hence, they are used for stuffing pillows, mattresses, sleeping bags, upholstery, and cushions.
Since they are water-repellent and capable of holding up multiple times their weight in water, these fibres from the Silk Cotton Tree are used in making lifeboats, life jackets, and other floating devices.
Since the Silk Cotton Tree fibers are good insulators, they are used in cold-storage plants, ice boxes, refrigerators, airplanes, and even movie theaters since they also provide acoustic insulation.
Since Silk Cotton Trees are very large, they are crucial in maintaining a stable ecosystem around them. Birds can nest in their branches, insects and butterflies get nectar from their flowers, and small animals can eat tender parts of the tree.
They provide shelter, shade, and protection for humans as well as other small animals like frogs and snakes that can nest in the large buttress roots. Since these trees support life, they are considered sacred in some countries.
Propagation
Propagation is through seeds, stem cuttings, and air layering.
Seeds can be collected from mature dry fruits and planted in moist soil to germinate, which might take many weeks. Semi-hardwood cuttings can also grow roots in soil, though this is not the easiest method of propagation.
Air layering involves removing a small piece of the skin from a bark and wrapping it in sphagnum moss. This area is then kept moist to grow roots. Once the roots are produced, that part can be detached from the parent plant, and replanted.
Photographed at: Lalbagh, Bangalore, GKVK Agricultural college, Bangalore
