A closer look at weeds: part 3

Dandelions (Taraxacum officinale) are the commonest of our wildflowers. They grow everywhere: between our paving stones, in flowerbeds, lawns and roadside verges, and straight up through the tarmac of a well-maintained driveway.

The dazzling yellow flower-head is made of many separate florets. Each one has what looks like a single petal but is, in fact, five petals fused together; you can see the joins at the toothed edge of the floret. At the other end is the tuft of fibres that will eventually become the parachute that the seed will fly away on.

In between, the stigma (the female part of the flower) grows up through the tube-like anthers (the male part of the flower) and splits into two coils.

Dandelion sex is really complicated. They can reproduce sexually either by cross fertilisation or by self fertilisation but most British dandelions don’t do either and produce seed without being fertilised at all, a process called apomixis.

Dandelions have swapped the genetic variability of cross fertilisation for the repetition of the traits that have been the means of their success; a risk that has paid off. This means that all the dandelions in your garden will probably be clones of a single parent plant.

Even cloned dandelions still respond to environmental pressure and this asexually reproducing species has formed, in Britain, about 200 micro-species. The whole subject of dandelion reproduction is so big and so complex it has become an ology all by itself with its own experts: taraxacologists!

All three of the species we have looked at closely in this mini-series on weeds have extraordinary and complex lives. They each have found intricate solutions to difficult environmental problems, solutions that have contributed to their success. If we manage to damage our own environment to the point where dandelions, red dead nettle and ground ivy can no longer live in it, we will know we are in real trouble.

Conservation status: common and widespread

All pictures by Suzanne Humphries


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