Are You Sucking on a Lemon or a Lime?:
[Via Catalogue of Organisms]
The genus Citrus is one of the most significant groups of fruit trees around the world. An overwhelming diversity of fruit varieties are produced by Citrus, such as oranges, lemons, grapefruit, tangelos, citrons, bergamots, mandarins, and the wonderfully-named ugli fruit (and yes, it is). Technically, the fruit of Citrus is a specialised type of berry called a hesperidium, named after the mythical garden of the Hesperides where golden fruit were tended by airy nymphs watched over by a giant serpent, suggesting that Greek prophets had also predicted the eventual appearance of Benny Hill. The hesperidium distinguished by its leathery, acidic rind and division into segments, and is unique to a clade containing Citrus and a few closely related genera such as Poncirus and Fortunella (kumquats*), both of which have been included by at least some researchers in Citrus (de Araújo et al., 2003). From the taxonomist’s point of view, however, Citrus has always been a gigantic headache. The question of how to classify this kaleidoscopic array of varieties, most of them only known as cultivated forms with no record of their origins, presents a quandary perhaps rivalled among plants only by the similarly over-cultivated genus Brassica. In the two main classifications that have been used for Citrus, that presented by Swingle in 1943 recognised sixteen species in the genus, while that of Tanaka in 1977 recognised one-hundred and sixty-two (Jung et al., 2005).
*Some time ago, I commented on the misleadingly obscene sound of words such as “yeast”, “moist” and “sphagnum”. None of these words, however, comes even close in this regard to the filth innocently suggested by “kumquat”.
[More]
I never realized just how unusual citrus germination was. And all the varieties of citrus fruit may only have come from 3 or 4 different species. Another great example of the effect of human intervention in the shaping of a species on the planet.
Technorati Tags: Environment, Science
