Gossypium

Cotton is the primary natural fibre used by humans today, amounting to about 80% of world natural fibre production. 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.

The origin of the genus Gossypium is dated to around 5–10 million years ago. Gossypium species are distributed in arid to semiarid regions of the tropics and subtropics. Generally shrubs or shrub-like plants, the species of this genus are extraordinarily diverse in morphology and adaptation, ranging from fire-adapted, herbaceous perennials in Australia to trees in Mexico. 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.

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 (97% of world production), G. barbadense (1–2%), G. arboreum and G. herbaceum (together, ~1%). 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.

Species

55 species are accepted.

• Gossypium anapoides J.M.Stewart, Craven, Brubaker & Wendel
• Gossypium anomalum Wawra & Peyr.
• Gossypium arboreum L. – tree cotton (India and Pakistan)
• Gossypium areysianum Deflers
• Gossypium aridum (Rose & Standl.) Skovst.
• Gossypium australe F.Muell (northwestern Australia)
• Gossypium barbadense L. – Creole cotton/Sea Island Cotton (tropical South America)
• Gossypium bickii (F.M.Bailey) Prokh.
• Gossypium bricchettii (Ulbr.) Vollesen
• Gossypium californicum Mauer
• Gossypium contextum O.F.Cook & J.W.Hubb.
• Gossypium costulatum Tod.
• Gossypium cunninghamii Tod.
• Gossypium darwinii G.Watt – Darwin's cotton (Galápagos Islands)
• Gossypium dicladum O.F.Cook & J.W.Hubb.
• Gossypium ekmanianum Wittm.
• Gossypium enthyle Fryxell, Craven & J.M.Stewart
• Gossypium exiguum Fryxell, Craven & J.M.Stewart
• Gossypium gossypioides (Ulbr.) Standl.
• Gossypium harknessii Brandegee
• Gossypium herbaceum L. – Levant cotton (southern Africa and the Arabian Peninsula)
• Gossypium hirsutum L. – upland cotton (Central America, Mexico, the Caribbean and southern Florida)
• Gossypium hypadenum O.F.Cook & J.W.Hubb.
• Gossypium incanum (O.Schwartz) Hillc.
• Gossypium irenaeum Lewton
• Gossypium klotzschianum Andersson
• Gossypium laxum L.Ll.Phillips
• Gossypium lobatum Gentry
• Gossypium londonderriense Fryxell, Craven & J.M.Stewart
• Gossypium longicalyx J.B.Hutch. & B.J.S.Lee
• Gossypium marchantii Fryxell, Craven & J.M.Stewart
• Gossypium morrilli O.F.Cook & J.W.Hubb.
• Gossypium mustelinum Miers ex G.Watt
• Gossypium nelsonii Fryxell
• Gossypium nobile Fryxell, Craven & J.M.Stewart
• Gossypium patens O.F.Cook & J.W.Hubb.
• Gossypium pilosum Fryxell
• Gossypium populifolium (Benth.) F.Muell. ex Tod.
• Gossypium pulchellum (C.A.Gardner) Fryxell
• Gossypium raimondii Ulbr. – one of the putative progenitor species of tetraploid cotton, alongside G. arboreum
• Gossypium robinsonii F.Muell.
• Gossypium rotundifolium Fryxell, Craven & J.M.Stewart
• Gossypium schwendimanii Fryxell & S.D.Koch
• Gossypium somalense (Gürke) J.B.Hutch., Silow & S.G.Stephens
• Gossypium stephensii J.P.Gallagher, C.E.Grover & Wendel
• Gossypium stocksii Mast.
• Gossypium sturtianum J.H. Willis – Sturt's desert rose (Australia)
• Gossypium thurberi Tod. – Arizona wild cotton (Arizona and northern Mexico)
• Gossypium timorense Prokh.
• Gossypium tomentosum Nutt. ex Seem – Maʻo or Hawaiian cotton (Hawaii)
• Gossypium trifurcatum Vollesen
• Gossypium trilobum (DC.) Skovst.
• Gossypium triphyllum (Harv.) Hochr.
• Gossypium turneri Fryxell
• Gossypium vollesenii Fryxell}

Formerly placed in genus Gossypium

• Gossypioides brevilanatum (Hochr.) J.B.Hutch. (as G. brevilanatum Hochr.)
• Gossypioides kirkii (Mast.) J.B.Hutch. (as Gossypium kirkii Mast.)
• Kokia drynarioides (Seem.) Lewton (as G. drynarioides Seem.)