Sunday, January 11, 2015

Dandelion

To be honest, this was taken in Swansea not Sussex. However, it was taken by my son on Christmas day, so at least it's temporally close to the mark.
And what is it? Well it's easy to give the common names: dandelion, wet-the-bed, pissy beds, jack-piss-the-bed, old man's clock, peasant's clock, swine's snout. But the binomial? 


That's a different matter, because identification at the species level is fraught with difficulty. 

This is partly due to close similarity between species, and partly due to a lack of consensus as to how many species there are and which ones count as species. So the common way of dealing with this is to refer to your average dandelion as Taraxacum agg. or belonging to the Taraxacum aggregation. 

So why the references to urination and why the taxonomical complexity?

Dandelions have been an important food and medicine source wherever they're found. The leaves are eaten in salads or blanched and used like spinach. They are markedly dentate or toothed, from whence their commonest name derives: dents de lion. The roots are used in drinks like dandelion and burdock, root beer and roasted and ground to make a caffeine-free coffee substitute. The roots have the unfortunate side-effect of inducing diuresis - the production of urine.

They are in the same family, Asteraceae, as our friend the daisy, but unlike daisy, they can reproduce asexually by apomixis. This results in offspring genetically identical to the parent. Such goings-on results in lots of 'microspecies' which are genetically unique, but whose physical characteristics are subtly different. Hence the difficulty in the field. About 235 microspecies have been identified in the British Isles. Telling them apart is an arcane business and something of a dark art, with only a handful of grand-masters like John Richards, Professor of Botany at the University of Newcastle.
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