#83 Dandelions by Anne Readshaw
Meet Anne Readshaw, part of Natural England's Yorkshire and Northern Lincolnshire Area Team and Chair of Yoredale Natural History Society!
Anne loves plants and has been lucky enough to have worked with them in some form or other throughout her career. After a BSc in Biology and an MSc in Crop Protection, she started out as a Plant Pathologist with ICI. After a career break to bring up her family, she earned a PhD in Molecular Genetics of Plant Development, at the University of York. She then worked for many years as a Post Doc in the same department, using the model plant Arabidopsis to research various aspects of plant biology. More recently, she started working for Natural England and now works on nature recovery and protected sites as part of the Yorkshire and Northern Lincolnshire Area Team. Outside of work, Anne maintains her keen interest in botany as a member of BSBI and Chair of Yoredale Natural History Society.
Dandelions are one of our best-known wild plants, popping up everywhere in many different habitats, and of course in everybody’s gardens, paths and driveways. They have a long flowering period – from March to October – though the peak is in May, when masses of them brighten up our roadside verges, signalling that spring is properly underway.
Their shaggy golden flowers resemble a cartoon lion’s mane, but this is not why they are called Dandelions. In fact, the word ‘dandelion’ comes from the French ‘dent-de-lion’, meaning ‘lion’s tooth’, because of the jagged shape of their leaves. The French also call them ‘pis-en-lit’, which is a colourful reference to their strong diuretic effect (1).
If you don’t mind what the French say, all parts of Dandelion plants are nutritious and can be eaten, and in some countries, they are cultivated specially for this. The leaves can be unpalatably bitter, though this may be reduced by blanching or shallow frying. The bitterness comes from the sticky ‘Dandelion milk’, or latex, that exudes from the plant’s tissues when damaged, as anyone who’s ever picked a Dandelion can recall. Chemical compounds within the latex have been shown to repel herbivores (especially Cockchafer beetles, whose larvae like to feed on roots underground) (2). Some Dandelion varieties contain so much latex that studies have been carried out to determine whether it could be extracted and made into useful rubber (3).
Although at first glance all Dandelions look roughly similar, there are actually hundreds of different ‘micro-species’, usually lumped together by botanists as ‘Taraxacum agg.’ Professor John Richards of Newcastle University has written an excellent handbook (4), containing keys which help you identify them more precisely. To do this, you have to collect a specimen in peak condition and become familiar with some botanical terms, like ligule, stape, involucre, pruinose... Then a morning spent solving the puzzle of an interesting-looking Dandelion found in your local park becomes a pleasant change from Sudoku or Wordle, and once you have identified a few, you will never be able to walk past a flowering Dandelion again, without taking some of it home, or at least stopping to ponder.
Another interesting fact about Dandelions is that most of them (in the UK at least) are apomictic, meaning that they produce seed asexually, so each seedling is usually an exact clone of the mother plant. This has important implications taxonomically, but at least it means that Dandelions generally can’t hybridise with each other, which would greatly complicate the keying-out process described above.
However, to make matters trickier, Dandelions exhibit a high degree of phenotypic plasticity, meaning that identical clones often look completely different, depending on their age, the time of year, the soil and the other conditions they find themselves growing under. Although this gives botanists a headache, it makes Dandelions consummate survivors, able to maximise the output of their wind-borne seeds, whatever their situation. They are also able to propagate themselves from tiny root fragments, and their long tap-root makes them resistant to drought, trampling and herbivory. These features all contribute to the ‘weediness’ of dandelions and explain why they are so well-adapted to take advantage of disturbed ground, and why gardeners and village greenkeepers tend to hate them so much.
Honey Bee on Dandelion, Clare Langrick
It’s a shame that Dandelions are so much maligned. There is a lot about them to like. Their flowers provide nectar for bees, butterflies and other insects, bridging a gap at times of the year when there is not much other food available for pollinators. The seed heads (or ‘clocks’) are enjoyed by birds, such as goldfinches and linnets – as well as school children wanting to tell the time, of course. Their deep roots benefit soil structure, by accessing and recycling nutrients and water that other plants’ roots can’t reach.
So, to gardeners I would urge patience – enjoy the Dandelion spectacle for those few short weeks in spring, and think of the ecosystem benefits. Better still, get hold of a copy of the field handbook and start taking a closer look at those cheerful and ubiquitous yellow flowers!
Recording and monitoring
Records of Dandelion species can be submitted to online platforms like iRecord or iNaturalist, or submitted to your local LERC.
Further information and acknowledgements
NEYEDC would like to thank Anne for her time and expertise in helping to create this blog.
References
(1) Clare, B.A. et al (2009) ‘The Diuretic Effect in Human Subjects of an Extract of Taraxacum officinale Folium over a Single Day.’ Journal of Alt. and Comp. Medicine 15(8):929-934. DOI 10.1089/acm.2008.0152
(2) Huber, M. et al (2016) ‘A latex metabolite benefits plant fitness under root herbivore attack.’ PLOS Biology, Open Access. DOI 10.1371/journal.pbio.1002332.
(3) Salehi, M. et al (2022) ‘Rubber and Latex Extraction processes for Taraxacum kok-saghyz.’ Industrial Crops and Products (178) 114562. DOI 10.1016/j.indcrop.2022.114562
(4) Richards, A.J. (2021) Field Handbook to British and Irish Dandelions. BSBI Handbook No. 23. Botanical Society of Britain and Ireland, Durham.