|Wild cabbage plants|
Brassica oleracea is the species of plant that includes many common foods as cultivars, including cabbage, broccoli, cauliflower, kale, Brussels sprouts, savoy, and Chinese kale. In its uncultivated form it is known as wild cabbage. It is native to coastal southern and western Europe. Its tolerance of salt and lime and its intolerance of competition from other plants typically restrict its natural occurrence to limestone sea cliffs, like the chalk cliffs on both sides of the English Channel.
Wild B. oleracea is a tall biennial plant, forming a stout rosette of large leaves in the first year, the leaves being fleshier and thicker than those of other species of Brassica, adaptations to store water and nutrients in its difficult growing environment. In its second year, the stored nutrients are used to produce a flower spike 1 to 2 metres (3–7 ft) tall bearing numerous yellow flowers.
Cultivation and uses 
B. oleracea has become established as an important human food crop plant, used because of its large food reserves, which are stored over the winter in its leaves. It is rich in essential nutrients including vitamin C. Although it is believed to have been cultivated for several thousand years, its history as a domesticated plant is not clear before Greek and Roman times, when it was a well-established garden vegetable. Theophrastus mentions three kinds of rhaphanos (ῤάφανος): a curly-leaved, a smooth-leaved, and a wild-type. He reports the antipathy of the cabbage and the grape vine, for the ancients believed cabbages grown near grapes would impart their flavour to the wine. It has been bred into a wide range of cultivars, including cabbage, broccoli, cauliflower, and more, some of which are hardly recognisable as being members of the same genus, let alone species. The historical genus of Crucifera, meaning four-petalled flower, may be the only unifying feature beyond taste.
- Brassica oleracea Acephala Group – kale and collard greens
- Brassica oleracea Alboglabra Group – Chinese broccoli
- Brassica oleracea Botrytis Group – cauliflower, Romanesco broccoli and broccoflower
- Brassica oleracea Capitata Group – cabbage
- Brassica oleracea Gemmifera Group – brussels sprouts
- Brassica oleracea Gongylodes Group – kohlrabi
- Brassica oleracea Italica Group – broccoli
For other edible plants in the family Brassicaceae, see cruciferous vegetables.
In places such as the Channel Islands and Canary Islands where the frost is minimal and plants are thus freed from seasonality, some cultivars can grow up to three meters tall. These "tree cabbages" yield fresh leaves throughout the year, and harvest does not mean the plant needs to be destroyed as with a normal cabbage. Their woody stalks are sometimes dried and made into walking sticks.
- Compare Theophrastus; raphanis (ραφανίς), "radish", also a Brassica.
- Daniel Zohary and Maria Hopf, Domestication of plants in the Old World, third edition (Oxford: Oxford University Press, 2000), p. 199.
- Theophrastus, Enquiry into Plants, IV.6.16; Deipnosophistae, I, noting the effects of cabages on wine and wine-drinkers, also quotes Apollodorus of Carystus: "If they think that our calling it a rhaphanos, while you foreigners call it a krambê, makes any difference to us women!" (on-line English text).
- Dixon, G.R. (2007), Vegetable brassicas and related crucifers, Wallingford: CABI, ISBN 978-0-85199-395-9
- Williams, Paul H.; Hill, Curtis B. (June 13, 1986), "Rapid-Cycling Populations of Brassica" (pdf), Science, New Series (American Association for the Advancement of Science) 232 (4756): 1385–1389, doi:10.1126/science.232.4756.1385, PMID 17828914 Unknown parameter
- PROTAbase on Brassica oleracea (Brussels sprouts)
- PROTAbase on Brassica oleracea (cauliflower and broccoli)
- Video Overview of Brassica oleracea: from Untamed Science
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