Bombax is a genus of mainly tropical trees in the mallow family. They are native to western Africa, the Indian subcontinent, Southeast Asia, and the subtropical regions of East Asia and northern Australia. It is distinguished from the genus Ceiba, which has whiter flowers.
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 four species are recognised, although 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.
The tree appears on the flag of Equatorial Guinea.