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Gossypium L. is a genus of 52 described and accepted species of herbaceous perennials and small trees belonging to tribe Gossypieae and subfamily Malvoideae of the angiosperm family Malvaceae sensu APG, with a pantropical distribution in arid habitats. Four species - the Old World Gossypium arboreum and Gossypium herbaceum, and the New World Gossypium barbadense and Gossypium hirsutum - are the source of cotton, the world's preeminent fibre crop. Consequently Gossypium has been the subject of more research than any other genus of Malvaceae, including the specialist journals Cotton Research Journal (formerly Journal of the Indian Society for Cotton Improvement), Cotton Science (formerly Acta Gossypii Sinica), Journal of Cotton Science, Journal of Cotton Research, Journal of Cotton Research and Development, and historically Cotton Growing Review (formerly Empire Cotton Growing Review), Indian Cotton Journal (formerly Indian Cotton Growing Review) and Indian Cotton Development Journal.
Gossypium is thought to be a paleopolyploid. Most species are diploid with chromosome counts of 2n=26, but there are several tetraploid species with 2n=52, and hexaploid lines have been produced as part of plant breeding efforts. It is divided taxonomically into 4 subgenera and 8 sections, and karyologically into 8 diploid and 1 tetraploid genome groups, with a total of 52 species. Subgenus Gossypium is composed of the Afro-Asian diploid species, subgenus Sturtia of the Australian diploid species, subgenus Houzingenia of the American diploid species, and subgenus Karpas of the American and Pacific tetraploid species. Several artificial tetraploid, hexaploid and octaploid lines have been produced.
As a genus Gossypium has a broad distribution in the semi-arid and arid area of the tropics and subtropics. Subgenus Gossypium is native to Africa, South West and South Asia, and is naturalised in Central Asia, Indo-China and southern China, and Brazil. Subgenus Houzingenia is primarily Mexican, extending into Arizona, with single species in each of Peru and the Galapagos Islands. Subgenus Karpas is native from northern Brasil and Peru to northern Mexico, and in the Lesser Antilles, also also in the Galapagos Islands, Santo Domingo, Hawaii and Wake Atoll, and is cultivated and naturalised in much of tropical Africa, South and South East Asia, and south China. Subgenus Sturtia is native to Australia. 
The primary economic use of Gossypium stems from the seed fibres, which are spun to form cotton threads, and thence used in textile production.
Cottonseed oil and cottonseed meal are a bycrop. Cottonseed oil is refined from the seeds, with the toxin gossypol and other unwanted components removed, and formulated into vegetable oils and fats for culinary use. Untreated cottonseed oil is used as an insecticide. Cottonseed meal is the residue of the seed after extraction of the oil. It is used as feed for ruminants. (Ruminant digestive systems can detoxify the gossypol; this is not the case for other livestock.)
There is a modern consensus on the division of the genus into 4 subgenera, the division of 3 of those subgenera into 7 sections, and 3 of those sections into 10 subsections, as shown in the table below. These infraspecific taxa correspond to genome groups (denoted A-G and K for diploids, and AD for tetraploids) identified by cytological studies.
As a group containing major crop species Gossypium has historically been oversplit, with nearly 300 species described (a great number being variants of the cultivated species), and several of the subordinate taxa being recognised as segregate genera (e.g. Thurberia, Selera).
Subgenus Gossypium section Gossypium contains Gossypium arboreum L. and Gossypium herbaceum L. Subsection Anomala contains Gossypium anomalum Wawra, Gossypium capitis-viridis Mauer and Gossypium triphyllum (Haw.) Hochr. Subsection Longiloba is monotypic, consisting of Gossypium longicalyx J.B. Hutch. & B.J.S.Lee. Subsection Pseudopambak contains Gossypium stocksii Mast., Gossypium somalense (Gurke) J.B. Hutch., Gossypium areysianum Deflers and Gossypium incanum (O.Schwartz) Hillc., and provisionally the poorly known species Gossypium benadirense (Ulbr.) Vollesen, Gossypium bricchettii (Ulbr.) Vollesen and Gossypium vollesenii Fryxell. Gossypium trifurcatum Vollesen, distinguished from the other species by the presence of dentate leaves, and placed in section Serrata, may be correctly placed in subsection Anomala or in subsection Pseudopambak.
Subgenus Sturtia section Sturtia is composed of Gossypium stuartianum (R.Br.) J.H.Willis, Gossypium robinsonii F.Muell. and Gossypium nandewarense Derera. Section Hibiscoidea is composed of Gossypium australe F. Muell., Gossypium bickii (F.M.Bailey) Prokh. and Gossypium nelsonii Fryxell. Section Grandicalyx is composed of 12 species from northern and northwestern Australia: Gossypium anapoides J.M.Stewart, Craven, Brubaker & Wendel, Gossypium costulatum Tod., Gossypium cunninghamii Tod., Gossypium enthyle Fryxell, Craven & J.M.Stewart, Gossypium exiguum Fryxell, Craven & J.M.Stewart, Gossypium londonderriense Fryxell, Craven & J.M.Stewart, Gossypium marchantii Fryxell, Craven & J.M.Stewart, Gossypium nobile Fryxell, Craven & J.M.Stewart, Gossypium pilosum Fryxell, Gossypium populifolium (Benth.) F.Muell. ex Tod., Gossypium pulchellum (C.A.Gardner) Fryxell and Gossypium rotundifolium Fryxell, Craven & J.M.Stewart.
Subgenus Houzingenia is composed of 13 species, 11 from Mexico, 1 from Peru, and 1 from the Galapagos Islands. Gossypium raimondii Ulbr. (Peru) is the sole species of subsection Austroamericana. Gossypium aridum (Rose & Standl.) Skovst., Gossypium laxum L.Ll.Phillips, Gossypium lobatum Gentry and Gossypium schwendimanii Fryxell & S.D.Koch make up subsection Erioxylum. Gossypium gossypioides (Ulbr.) Standl. is the sole species of subsection Selera. Gossypium armourianum Kearney, Gossypium harknessii Brandegee and Gossypium turneri Fryxell form subsection Caudicibracteola. Gossypium thurberi Tod. and Gossypium trilobum (Moc. & Sessé ex DC.) Skovst. form subsection Houzingenia. Gossypium davidsonii Kellogg and Gossypium klotzschianum Andersson form subsection Integrifolia.
Subgenus Karpas is composed of the cultivated Gossypium barbadense L. and Gossypium hirsutum L., and the wild Gossypium darwinii G.Watt (Galapagos Islands), Gossypium ekmanianum Wittm. (Dominican Republic), Gossypium mustelinum Miers ex G.Watt (Bahia, Brazil), Gossypium stephensii J.P.Gallagher, C.E.Grover & Wendel (Wake Atoll) and Gossypium tomentosum Nutt. ex Seem. (Hawaii). The native ranges of Gossypium barbadense and Gossypium hirsutum are obscured by establishment of naturalised populations, but are in the general region of northern South America, Central America, Mexico and the Caribbean. POWO gives the native range of Gossypium barbadense as Columbia, Ecuador and Peru, and that of Gossypium hirsutum as Mexico to Ecuador and northeastern Brasil.
Gossypium hirsutum has 7 identifiable regional land races - latifolium, marie-galante, morrilli, palmeri, punctatum, richmondii and yucatanense.
A number of artificial polyploid lines have been created..
The cytology of Gossypium has been extensively studied. As an outgrowth of this conventional designations for each of the genomes have been defined, as shown in the table below. At and Dt refer to the individual diploid genomes making up the tetraploid genome.
|(AD)1||Gossypium hirsutum L.|
|(AD)2||Gossypium barbadense L.|
|(AD)3||Gossypium tomentosum Nutt. ex Seem.|
|(AD)4||Gossypium mustelinum Miers ex Watt|
|(AD)5||Gossypium darwinii Watt|
|(AD)6||Gossypium ekmanianum Wittm.|
|(AD)7||Gossypium stephensii J.Gallagher, C.E.Grover & Wendel|
|A1||Gossypium herbaceum L.|
|A1-a||Gossypium herbaceum subsp. africanum (G. Watt) Vollesen|
|A2||Gossypium arboreum L.|
|B1||Gossypium anomalum Wawra ex Wawra & Peyr.|
|B2||Gossypium triphyllum (Harv.) Hochr.|
|B3||Gossypium capitis-viridis Mauer|
|C1||Gossypium sturtianum Willis|
|C1-n||Gossypium sturtianum var. nandewarense Derera|
|C2||Gossypium robinsonii F.Muell.|
|D1||Gossypium thurberi Tod.|
|D2-1||Gossypium armourianum Kearney|
|D2-2||Gossypium harknessii Brandegee|
|D3-d||Gossypium davidsonii Kellogg|
|D3-k||Gossypium klotzschianum Andersson|
|D4||Gossypium aridum (Rose & Standl.) Skovst.|
|D5||Gossypium raimondii Ulbr.|
|D6||Gossypium gossypioides (Ulbr.) Standl.|
|D7||Gossypium lobatum Gentry|
|D8||Gossypium trilobum (Sessé & Moc. ex DC.) Skovst.|
|D9||Gossypium laxum Phillips|
|D10||Gossypium turneri Fryxell|
|D11||Gossypium schwendimanii Fryxell & S.D.Koch|
|E1||Gossypium stocksii Mast. in Hook.|
|E2||Gossypium somalense (Gürke) J.B.Hutch., Silow & S.G.Stephens|
|E3||Gossypium areysianum (Deflers) J.B.Hutch., Silow & S.G.Stephens|
|E4||Gossypium incanum (O.Schwartz) Hillc.|
|F1||Gossypium longicalyx J.B.Hutch. & B.J.S.Lee|
|G1||Gossypium bickii (F.M.Bailey) Prokh.|
|G2||Gossypium australe Muell.|
|G3||Gossypium nelsonii Fryxell|
|K1||Gossypium exiguum Fryxell, Craven & J.M.Stewart|
|K2||Gossypium rotundifolium Fryxell, Craven & J.M.Stewart|
|K3||Gossypium populifolium (Benth.) F.Muell.|
|K4||Gossypium pilosum Fryxell|
|K5||Gossypium marchantii Fryxell, Craven & J.M.Stewart|
|K6||Gossypium londonderriense Fryxell, Craven & J.M.Stewart|
|K7||Gossypium enthyle Fryxell, Craven & J.M.Stewart|
|K8||Gossypium costulatum Tod.|
|K9||Gossypium cunninghamii Tod.|
|K10||Gossypium pulchellum (C.A.Gardner) Fryxell|
|K11||Gossypium nobile Fryxell, Craven & J.M.Stewart|
|K12||Gossypium anapoides J.M.Stewart, Craven, Brubaker & Wendel|
The genome of Gosspium australe was previously denoted C3, and that of Gossypium longicalyx E5.
The phylogeny of Gossypium has been extensively studied using cytological, biochemical, phenetic, and more recently DNA sequence data.
© 2020, 2022 Stewart Robert Hinsley