Citrus: Encyclopedia II - Citrus - Citrus fruits

Citrus - Citrus fruits

Citrus fruits are notable for their fragrance, and most are juice-laden. They contain a high proportion of citric acid giving them their characteristic astringent odour and flavour. They are also good sources of vitamin C, and apparently flavonoids. In botanical terms, "The fruit of all Citrus trees, in which the true fruit is the peel, [is] made up of an outer layer, brightly colored and rich in glands, a spongey whitish mesocarp, and a membraneous endocarp surrounding the segments. The succulent parts we eat is only a secondary tissue developed as a filler" - Paola Lanzara and Mariella Pizzetti Simon & Schuster's Guide to Trees, pp. 44.

As citrus trees hybridize very rapidly (e.g., seeds grown from limes can produce fruit similar to grapefruit), all commercial citrus cultivation uses trees produced by grafting the desired fruiting cultivars onto rootstocks selected for disease resistance and hardiness.

The colour of citrus fruits only develops in climates with a cool winter. In tropical regions with no winter, citrus fruits remain green until maturity, hence the tropical "green orange". The lime plant in particular is extremely sensitive to cool conditions, thus it is usually never exposed to cool enough conditions to develop a colour. If they are left in a cool place over winter, the fruits will actually change to a yellow colour.

Adapted from the Wikipedia article "Citrus fruits", under the G.N U Free Docmentation License. Please also see http://en.wikipedia.org/wiki