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Apple (116323)
The apple is a tree and its pomaceous fruit, of the species Malus domestica in the rose family Rosaceae. It is one of the most widely cultivated tree fruits. It is a small deciduous tree reaching 5-12 m tall, with a broad, often densely twiggy crown. more...
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The leaves are alternately arranged, simple oval with an acute tip and serrated margin, slightly downy below, 5-12 cm long and 3-6 cm broad on a 2-5 cm petiole. The flowers are produced in spring with the leaves, white, usually tinged pink at first, 2.5-3.5 cm diameter, with five petals. The fruit matures in autumn, and is typically 5-9 cm diameter (rarely up to 15 cm). The centre of the fruit contains five carpels arranged star-like, each carpel containing one or two (rarely three) seeds.
Botanical origins
The wild ancestor of Malus domestica is Malus sieversii. It has no common name in English, but is known in Kazakhstan, where it is native, as "alma"; in fact, the region where it is thought to originate is called Alma-Ata, or "father of the apples". This tree is still found wild in the mountains of Central Asia in southern Kazakhstan, Kyrgyzstan, Tajikistan, and Xinjiang, China.
For many years, there was a debate about whether M. domestica evolved from chance hybridisation among various wild species. Recent DNA analysis by Barrie Juniper, Emeritus Fellow in the Department of Plant Sciences at Oxford University and others, has indicated, however, that the hybridisation theory is probably false. Instead, it appears that a single species still growing in the Ili Valley on the northern slopes of the Tien Shan mountains at the border of northwest China and the former Soviet Republic of Kazakhstan is the progenitor of the apples we eat today. Leaves taken from trees in this area were analyzed for DNA composition, which showed them all to belong to the species M. sieversii, with some genetic sequences common to M. domestica.
Some individual M. sieversii, recently planted by the US government at a research facility, resist many diseases and pests that affect domestic apples, and are the subject of continuing research to develop new disease-resistant apples.
Other species that were previously thought to have made contributions to the genome of the domestic apples are Malus baccata and Malus sylvestris, but there are no hard evidence for this in older apple cultivars. These and other Malus species have been used in some recent breeding programmes to develop apples suitable for growing in climates unsuitable for M. domestica, mainly for increased cold tolerance.
The apple tree was perhaps the earliest tree to be cultivated, and apples have remained an important food in all cooler climates. To a greater degree than other tree fruit, except possibly citrus, apples store for months while still retaining much of their nutritive value. Winter apples, picked in late autumn and stored just above freezing, have been an important food in Asia and Europe for millennia, as well as in Argentina and in the United States since the arrival of Europeans.
Read more at Wikipedia.org
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