Gossypium barbadense
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Gossypium barbadense , illustration |
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Gossypium barbadense is a plant from the genus cotton ( Gossypium ). It comes from tropical America and is now widely grown for the production of cotton fibers.
description
Gossypium barbadense grows as a perennial shrub or shrub that m reaches a height 2 to 3 In culture, the plant is grown as an annual. The stem axis is dark reddish and angular. The hairiness can extend to the whole plant or be limited to the petioles and the veins on the underside of the leaves. The leaves are three or five lobed, the leaves of the primary stem axis also seven lobed. The underside of the leaves is covered with nectaries . The leaf lobes are oval to inverted-ovate and end long drawn out. The leaf reaches a diameter of 7 to 14 cm long, the leaf base is heart-shaped, the petiole is longer than the leaf blade. The stipules are 1 to 5 cm long, they usually fall off soon.
The flowers are individually in the leaf axils or terminal. The flower stalks are 1 to 4 cm shorter than the leaf stalks. The outer calyx consists of three, according to other statements, five or more non-fused bracts . They are 6 cm long and 4.5 cm wide, with seven to nine 19 pointed prongs at the front and heart-shaped at the base. There are nectaries between the bracts. The bowl-shaped calyx is cut off straight, ciliate, there are often nectaries here too. The petals are light yellow with a dark red spot each at the base. They are 5 to 8 cm tall and are hairy on the outside. The Columna is 3.5 to 4 cm long, the stamens are close to it. The scar clearly protrudes beyond the stamen.
The capsule fruit is three, more rarely four-part, oval to elongated, pointed at the front or beaked. It becomes 3 to 7 cm long. The oval seeds are smooth and black, up to 0.8 cm in size. They are surrounded by long white fibers and short fibers that are not firmly attached.
The number of chromosomes is 2n = 4x = 52.
distribution
Gossypium barbadense is native to tropical America. It is cultivated worldwide in the tropics and subtropics. The fourfold set of chromosomes ( tetraploidy ) of Gossypium barbadense comes from two different parent species ( allopolyploidy ). One part of the chromosome set is similar to that of American species, the second part, however, to that of African species. When the crossing of the two original species took place is unclear: A point in time was suggested before the separation of Africa and South America (60-100 million years ago) or an exchange by humans a few hundred years ago. Molecular genetic studies, however, indicate that Gossypium barbadense was 1 to 2 million years old; It is unclear how the exchange of the spatially separated output species took place today on different continents.
use
Gossypium barbadense is a supplier of the longest, extra long staple (ELS) cotton fibers ; Pima, Supima, Egyptian cotton (Giza), Sea Island Cotton, with fibers up to 50 mm long. The first finds of fibers that are assigned to Gossypium barbadense come from fishing nets on the coast of Peru and date from 1500 to 2400 years before Christ. From there the plant was spread in pre-Columbian times in South America, the Caribbean and up to the Galápagos Islands . During this time, changes in breeding can already be observed: The short fibers around the seeds became fewer, the long fibers more and longer, and the seed coat lost its strength, so that the seeds germinate more quickly.
literature
- Ya Tang, Michael G. Gilbert, Laurence J. Dorr: Gossypium barbadense . In: Wu Zhengyi, Peter H. Raven (Ed.): Flora of China . tape 12 . Missouri Botanical Garden Press, St. Louis, S. 297 ( eFloras.org - 1994+).
Individual evidence
- ↑ a b c d e f g Ya Tang, Michael G. Gilbert, Laurence J. Dorr: Gossypium barbadense . In: Flora of China . Vol. 12, p. 297.
- ↑ a b c d e f g h i j The Biology of Gossypium hirsutum L. and Gossypium barbadense L. (cotton). (PDF; 1.1 MB) Australian Government, Department of Health and Aging, accessed on August 22, 2010 .
- ^ Julian Roche: The International Cotton Trade. Woodhead Publishing, 1994, ISBN 978-1-84569-281-0 , p. 54.
