Dandelion: a useful weed?

Common dandelion (Taraxacum officinale). Image by Franz Eugen Köhler, Köhler’s Medizinal-Pflanzen (public domain).

I have recently moved house and I now have a small garden to take care of. I’m pretty excited by this prospect and have been trying to decide what to try and grow in it. However, my little garden is currently somewhat overgrown with weeds—most of which are dandelions.

The common dandelion (Taraxacum officinale) belongs to the Daisy family (Compositae/Asteraceae) of flowering plants alongside more popular garden plants such as sunflowers. It is native to Eurasia but has spread to many other parts of the world including North America. The name dandelion derives from the French ‘dent de lion’, which means ‘lion’s tooth’ and refers to the deeply toothed leaves (1).

A common cause of frustration to gardeners, the common dandelion has several features that enable it to be a vigorous weed in most types of soil. Each flower head produces around 2000 seeds in white tufted fruits that form a puffy ball on the plant (so-called “dandelion clocks”). The seeds are dispersed by the wind and can survive dormant in the soil for many years until the conditions are right for them to germinate. Also, the plants produce a taproot that can grow up to 10-15 ft deep into the soil (2). Whole plants can regrow from a small fragment of taproot, which means that it can be very difficult to remove them from your garden.

When I was a child growing up in London, there was a house near me where, rumour had it, a hermit lived by eating the dandelions growing in his back garden. This story is, admittedly, probably just the imaginings of local children, but it isn’t quite as far-fetched as you might think. Dandelions are indeed edible: the leaves can be served raw or cooked and the flowers are used to make drinks including wine or cordial. Even the root is edible, and in the UK it was commonly ground up and to make a coffee substitute during the Second World War (1).

The common dandelion has other useful qualities. It is a diuretic and a laxative and has been traditionally used in medicine as a tonic, for rheumatic problems, and to purify the blood (1). Also, dandelions produce a milky-coloured sap that contains latex (rubber). The demand for latex is fueling research efforts to harvest it from dandelions. These efforts are focussing on the Russian dandelion (Taraxacum kok-saghyz), which produces sap with higher latex content than the common dandelion (3, 4).

So, a plant that is considered to be an annoying weed by many can be considered useful to others. The plant scientist in me does admire dandelions, but that isn’t going to stop me from trying to remove most of them from my flowerbeds. Let battle commence.

Common dandelions in bloom in my garden (Norfolk, UK)

Quite by accident Plant Scientist appears to be having a weed-themed month. Stay-tuned for more posts about plants that often find themselves in the “wrong” places.

In other news, this is the 100^th post on the blog. Hooray!

References:

1. Kew – Taraxacum officinale (dandelion) (retrieved 11/05/15)
2. UC IPM – How to manage pests: Dandelions (retrieved 11/05/15)
3. Science Daily – Rubber from Dandelions: Key components in formation of rubber identified. (retrieved 11/05/15)
4. Science Daily – Making rubber from dandelion juice (retrieved 11/05/15)