cotton plants

Gossypium arboreum L., G. herbaceum L.
Malvaceae
Old World Cotton

Gossypium herbaceum and G. arboreum are closely related and are descendant from the ancient african cotton Gossypium herbaceum var. afrikanum. Over 5000 years ago G. arboreum was cultivated in what is now Gujerat in India and such plants are still to be found in fields on the Indian subcontinent. Forms of G. herbaceum were developed in Persia and distributed through to India and China.

Cotton grows wild in parts of Africa and Asia and when left alone takes the form of a large bush or a small tree. In cultivation it is almost exclusively grown as an annual. Traditional short-hair varieties are still grown today in Pakistan and India but their use is dwindling. These varieties are only really competitive with modern hybrid cottons in areas without irrigation. In contrast, local varieties are valued in China among cotton growers especially, for their early ripening and greater resistance to cold.

Gossypium herbaceum

Gossypium arboreum

Gossypium barbadense L., G. hirsutum L.
Malvaceae
New World Cotton

An genetic investigation of traditional Central and SouthAmerican cottons reveals that these varieties are descendant from the cross-breeding of the ancient African cotton G. herbaceum var. africanum with several wild forms indegenous to the Americas. How the african genetic came to the Americas is unclear, but appears to have been introduced much later than contintinental drift. Gossypium barbadense was domesticated more than 4000 years ago in Peru, while G. hirsutum was brought into culture a further 1000 years earlier in Mexico. Due to their excellent fibre qualities and exceptional yields, the American cottons and hybrids thereof comprise the large majority of today's worldwide cotton harvest.

Cotton is very rarely grown as a perrenial crop in the Americas since the advent of international efforts to enforce a first-planting-date regime of integrated pest management. In remote places in Peru traditional practice continues, involving radical pruning of the plants after the first season and harvesting cotton bolls from the same plant over succeeding years.
New world cottons give mich higher yields than those from the Old World, their fibres are finer and generally longer, some measuring over 50mm. However, these crops demand irrigation and are more susceptable to pests and disease. when grown using modern agricultural techniques cotton requires more herbicides and pesticides than any other crop.

Gossypium barbadense "Peruvian Brown"

Gossypium hirsutum var. punctatum