Bombax is a genus of mainly tropical trees in the mallow family. They are native to western Africa, the Indian subcontinent, Southeast Asia, as well as sub-tropical regions of East Asia and northern Australia. Common names for the genus include Silk Cotton Tree, Simal, Red Cotton Tree, Kapok and simply Bombax. In Chinese they are known as Mumian (Chinese: 木棉; pinyin: mùmián), meaning “tree cotton”. Currently three species are recognised, though many plants have been placed in the genus that were later moved.
The genus is best known for the species B. ceiba, which is widely cultivated throughout tropical and sub-tropical regions of the world. It is native to southern and eastern Asia and northern Australia.
Bombax species are used as food plants by the larvae of some Lepidoptera species including the leaf-miner Bucculatrix crateracma which feeds exclusively on Bombax ceiba.
Bombax species are among the largest trees in their regions, reaching 30 to 40 metres in height and up to 3 metres trunk diameter. The leaves are compound with entire margins and deciduous, being shed in the dry-season. They measure 30 to 50 cm across and are palmate in shape with 5 to 9 leaflets. The calyx is deciduous, meaning it does not persist on the fruits. They bear 5 to 10 cm long red flowers between January and March while the tree is still leafless. The stamens are present in bundles in two whorls, while the staminal column lacks lobes. The ovary matures into a husk containing seeds covered by a fibre similar to that of the kapok (Ceiba pentandra) and to cotton, though with shorter fibres than cotton, that does not lend itself to spinning, making it unusable as a textile product.
Bombax ceiba, like other trees of the genus Bombax, is commonly known as cotton tree or tree cotton. This tropical tree has a straight tall trunk and its leaves are deciduous in winter. Red flowers with 5 petals appear in the spring before the new foliage. It produces a capsule which, when ripe, contains white fibres like cotton. Its trunk bears spikes to deter attacks by animals. Although its stout trunk suggests that it is useful for timber, its wood is too soft to be very useful.
The tree is widely planted in Malay, Indonesia, south China, Hong Kong and Taiwan. According to Chinese historical record, the king of Nam Yuet, Chiu To, gave a tree to the Emperor of Han dynasty in 2nd Century BC.
This tree is commonly known as Semal (Hindi:सेमल) in India. It is widely planted in parks and on roadsides there because of its beautiful red flowers which bloom in March/April. This tree is quite common in New Delhi although it doesn’t reach its full size of 60m there because of the semi arid climate. The cotton fibers of this tree can be seen floating in the wind around the time of early may.
This tree shows two marked growth sprints in India- in spring and during the monsoon months.