Bombax malabaricum Seeds | Malabar Silk Cotton Tree
LATIN NAME: Bombax malabaricum (syn. Bombax ceiba)
COMMON NAME: Malabar Silk Cotton Tree
Plant Profile
The silk cotton tree is a deciduous tree of thirty to forty metres with a straight buttressed trunk that is covered in conical spines when young, and large red flowers that open in February before any leaf. The fruit is a capsule that splits to release a mass of white silky fibre.
It grows from India through southern China to Indonesia, and in Yunnan and Guangdong it is planted in villages and in temple grounds. The tree is leafless for only a few weeks, and the flowers in that window are one of the sights of the tropical spring. The trunk of an old tree is grey and smooth above the spines, and the buttresses at the base can be a metre wide.
Science & Biotechnology
The flowers are pollinated by birds and by bats, and the red colour and the copious nectar are the advertisement. The stamens are fused into a tube with the style through the middle, so a visitor brushes pollen onto the stigma while reaching for nectar, and the fruit that follows is a five-valved capsule.
The silk in the capsule is not cotton. Cotton fibres are seed hairs of a different plant, while kapok is a mixture of hair and fibre from the inner wall of the capsule, and its cells are hollow and waxed, so it is buoyant and does not absorb water. That is why kapok was used in life jackets before synthetic foam.
Uses & Benefits
The fibre fills pillows, mattresses and life jackets, and it is used for insulation and for soundproofing. It is too short and too slippery to spin into yarn, so it is used as a stuffing rather than as a textile, which is the difference between kapok and cotton.
The seed is pressed for an oil used in soap and in cooking in some districts, and the young leaves and flowers are eaten as a vegetable in India. The trunk is cut for plywood and for canoes, and the bark is used as a fibre and in local medicine. The tree is planted as a street tree and in parks for its spring flower.
Growing from Seed
Sow fresh seed in a warm, moist mix at twenty-five to thirty degrees, and germination takes two to four weeks. The seed loses viability quickly, so sow it in the season it is collected. Soak it for a few hours before sowing to soften the coat.
Plant out in full sun in deep soil, and give the tree room: the trunk buttresses as it ages and the roots are wide. Water through the first two dry seasons, then leave it to the weather. It is frost tender when young, and the wood is brittle, so do not plant it where a limb can fall on a roof.
Our Take
A spectacular tropical flowering tree and the source of kapok, and one that needs heat, space and a safe distance from buildings. Plant it for February.
Related Reading
More species in the same orbit as Malabar Silk Cotton Tree: