Gossypium is a genus of flowering plants in the tribe Gossypieae of the mallow family, Malvaceae from which cotton is harvested. It is native to tropical and subtropical regions of the Old and New Worlds. There are about 50 Gossypium species, making it the largest genus in the tribe Gossypieae and new species continue to be discovered. The name of the genus is derived from the Arabic word goz, which refers to a soft substance.
Cotton is the primary natural fibre used by modern humans. Where cotton is cultivated it is a major oilseed crop and a main protein source for animal feed. Cotton is thus of great importance for agriculture, industry and trade, especially for tropical and subtropical countries in Africa, South America and Asia. Consequently, the genus Gossypium has long attracted the attention of scientists.
Cultivated cottons are perennial shrubs most often grown as annuals. Plants are 1–2 m high in modern cropping systems, sometimes higher in traditional, multiannual cropping systems, now largely disappearing. The leaves are broad and lobed, with three to five (or rarely seven) lobes. The seeds are contained in a capsule called a "boll", each seed surrounded by fibres of two types. These fibres are the more commercially interesting part of the plant and they are separated from the seed by a process called ginning. At the first ginning, the longer fibres, called staples, are removed and these are twisted together to form yarn for making thread and weaving into high quality textiles. At the second ginning, the shorter fibres, called "linters", are removed, and these are woven into lower quality textiles (which include the eponymous Lint). Commercial species of cotton plant are G. hirsutum (>90% of world production), G. barbadense (3–4%), G. arboreum and G. herbaceum (together, 2%). Many varieties of cotton have been developed by selective breeding and hybridization of these species. Experiments are ongoing to cross-breed various desirable traits of wild cotton species into the principal commercial species, such as resistance to insects and diseases, and drought tolerance. Cotton fibres occur naturally in colours of white, brown, green, and some mixing of these.
Most wild cottons are diploid, but a group of five species from America and Pacific islands are tetraploid, apparently due to a single hybridization event around 1.5 to 2 million years ago. The tetraploid species are G. hirsutum, G. tomentosum, G. mustelinum, G. barbadense, and G. darwinii.