Overlooked dandelion diversity in BC (and everywhere in North America?)

More than 100 species of exotic dandelion are reported for BC, previously erroneously identified as Taraxacum officinale and T. erythrospermum—concepts misapplied in North America. We can’t begin to sort out the natives from these highly diverse, pervasive exotic species until we get the basic sections figured out. Yet most people blithely pass these weedy plants by, hardly paying any attention to the differences that set them apart. We dismissively construe these plants according to faulty species concepts, relegating them to bins of taxonomic obscurity. Please reconsider your dandelion identifications people!

http://blog.cdnsciencepub.com/dandelion-diversity-overlooked-in-british-columbia/

4 Likes

Do you have any keys or ID help? If they are cryptic species, inat is probably not going to be a great place to try to parse these out, interesting as they are.

6 Likes

great to know that there is diversity, but now how do we, the iNat public, go about “paying any attention to the differences that set them apart” when these differences are hidden behind a paywall of Canadian Science Publishing? Are the differences things that will be easily recognizable in photos? Are there specific parts of the plants we need to be looking at closely?

4 Likes

Yes, I cringe now when I see dandelions ID’d to species, especially when the whole concept of species as applied to Taraxacum is questionable (from what I’ve read.) What would people recommend as a response when reviewing plant IDs? My first thought is to change the ID to genus, which will involve a lengthy explanation (yes, all the field guides are wrong, etc.)

1 Like

yeah, i don’t love going to genus unless the whole complex is unidentifiable. Are there sections within the genus? If we can find a reference that lays those out they are probably our best bet.

however it would be good to know which areas are difficult for dandelion ID and which areas we just have the two

1 Like

Here in the UK there are 9 sections recognized (sect. Erythrosperma, sect. Obliqua, sect. Palustria, sect. Spectabilia, sect. Naevosa, sect. Taraxacum, sect. Celtica, sect. Hamata & sect. Ruderalia). I have no idea if there are other sections present in other parts of the world.

1 Like

It is regrettable that the paper is not easily accessible. It provides a set of keys to the sections as a starting point. Keys to the species are forthcoming. No doubt it will be a while before the community recognizes this diversity, though… and maybe some people never will. Meanwhile though I think it is silly to keep calling our dandelions Taraxacum officinale.

I did a google search and came up with this:
https://tspace.library.utoronto.ca/bitstream/1807/94710/1/cjb-2018-0094.pdf

Either google crawled the link despite the paywall or the author uploaded the article somewhere else.

1 Like

If there’s a new treatment coming out it sounds like it doesn’t really matter what we call them because it will all change anyway. Lumping to genus lumps them with some rare native ones in California and such so I wouldn’t say that’s a good solution either. Though I often go to genus because without seeds I’m not confident separating the red seeded one (which I barely ever see in Vermont)

In the netherlands also Sectie Frugalia exists.
https://www.taraxacumnederland.nl/detemineersleutel-secties

https://www.herbariumfrisicum.nl/alle-collecties/taraxacum/
https://www.dutchnews.nl/news/2019/05/rare-dandelion-thought-extinct-in-nl-spotted-in-island-field/

1 Like

I’m not a taxonomist nor a Taraxacologist! But this is pretty damn interesting. Thanks for sharing @chlorophilia!

In case you don’t have access to the paper here are the takeaways.

First and most usefully for us, the author provides a database of photographs online that accompany the article: https://morphobank.org/index.php/Projects/ProjectOverview/project_id/3346

Second this paper applies European taraxacum taxonomy to some BC Taraxacum. Here are the key references it cites:

Richards, A.J. 1985. Sectional nomenclature in Taraxacum (Asteraceae).
Taxon, 34: 633–644. doi:10.2307/1222201.

Kirschner, J., and Št ˇep.nek, J. 1987. Again on the sections in Taraxacum (Cichoriaceae) (Studies in Taraxacum 6). Taxon, 36: 608–617. doi:10.2307/1221855.

Dudman, A.A., and Richards, A.J. 1997. Dandelions of Great Britain and Ireland. BSBI Handbook No. 9. Botanical Society of the British Isles. 344 pp.

This paper does include a key to the exotic sections in BC, this key appears to draw heavily from the work of Richards. I’ve attached this as an image here for reference:

While this is pretty cool–it does make me want to look at some dandelions–what’s a dandelion “species”? Some authorities believe that the genus “includes about 60 sections with about 2,800 species” (Kirchner et al 2015). My sense is that this points to Taraxacum being one of those “special cases” (all too normal really) where the species concept doesn’t quite work.

Given the special nature of dandelions. I found a (mildly acerbic) review of Richards dandelion book online (Atkinson 1998). Here’s a choice section:

“So why would you want to place a dandelion in one of the many species listed in this book? Their reproductive biology and ecology, although not covered in detail in this book, helps to explain the patterns of variation and there’s little doubt that the entities identified are real in nature. However, to my mind there is doubt about why they should be named. Sexual taxa may show a similar amount of variation to that encompassed by dandelions but the variation could only be taxonomically recognized by giving individuals a name, a thing no sane botanist would want to do. By naming apomictic lines taraxacologists are effectively naming every different genetic individual, which is taking taxonomic splitting to absurd extremes. However, someone has gone to the trouble of naming them, and if you’re on the lookout for an arcane hobby why not take up taraxacology? But, even with the aid of this book, you need to devote a good deal of time to identify a dandelion: so be warned, as the authors point out, ‘dandelions are difficult’.”

Kirschner, J., L. Záveská Drábková, J. Štěpánek, and I. Uhlemann. 2015. Towards a better understanding of the Taraxacum evolution (Compositae–Cichorieae) on the basis of nrDNA of sexually reproducing species. Plant Systematics and Evolution 301:1135–1156.

Atkinson, R. 1998. Dandelions of Great Britain and Ireland. BSBI Handbook No. 9. A. A. Dudman & A. J. Richards. Illustrations by Olga Stewart. Edited by P. H. Oswald. London: Botanical Society of the British Isles. 1997. 344 pp. ISBN 0 901158 25 9. £17.50 (paperback). Edinburgh Journal of Botany 55:321–322.

4 Likes

This definitely seems like another case where things are being declared species that might make more sense as subspecies.

amateur observer here…what part can I play to help with dandelion parsing? I never ID my own dandelion obs any other way than genus (I don’t walk by anything if I have enough time and battery power!). Can I take better photos to help with visual ID components or are we talking about non-visual cues/ elements? Maybe you are all rolling your eyes at my silly questions but I hate sitting on the sidelines and not at least trying to do what I can. :)

5 Likes

As far as photos, Bjork mostly got at least three views of each taxa in his study: the capitulum (‘flower’) from above, the capitulum from the side, showing the phyllary bracts, and a ‘habit’ shot, showing the overall growth form of the plant, including leaf shape and colour. This covers most of the key features that are likely to be visible on a photograph.

Important caveats about this paper:

  • it only provides a key to sections, not species, and it only covers British Columbia. From my discussions with the author, some of those sections don’t occur in eastern North America, and presumably there are sections in eastern North America that don’t appear in his key.
  • It’s not new taxonomic research; it’s the application of previous work in Europe to North American plants (of presumably European origin). That’s not to diminish it’s value in any way, just a caution against interpreting this one paper as having ‘solved’ Taraxacum in an authoritative way.
  • Taraxacum includes sexual diploids and apomictic polyploids. This makes their reproductive biology and evolutionary relationships extremely difficult to assess. I expect it will take a good deal of cytological and genetic data to properly sort out what’s going on here.

Bjork’s paper is an important contribution to understanding Taraxacum in North America, but it’s really only the beginning. If you’re interested in exploring this further, check it out, and some of the key references mentioned above, and see if you can apply it to your local dandelions. But for general community, and iNaturalist, use, I would argue that it’s premature to make any changes to the system in place here.

Anyone making serious study of Taraxacum will not be confused by the rest of us lumping all the introduced species into T. officinale. Trying to do better based on partial information from one corner of the continent will likely only confuse things further.

6 Likes

I have to agree here. And I also have to ask the (probably rhetorical) question: what are the chances that a large number of named apomictic lineages from Eurasia actually dispersed and successfully established in BC (or any other piece of North America) over the past 300 years? Versus maybe new convergent apomictic lines just having developed in place? Without also doing genetics, I would hesitate to apply Eurasian names to North American plants based solely on morphologic resemblance.

3 Likes

I have been wondering what to think of the Taraxacum officinale -observations from Finland. According to local literature, T. officinale does not occur here at all, but 3/4 of Finnish Taraxacums on iNat have been identified to that species. I have been unable to find out if this about differences in the taxonomy (i.e. different name is used for T. officinale here) or real differences in species distributions.

What this means is that anyone using the iNat data from Finland should interpret Taraxacum officinale as Taraxacum sp. This would not be a big problem, as iNat has only 35 Taraxacum observations from Finland.

But on the other hand, if the data is used to automatically create distribution maps, that manual interpretation is missing. The result is that e.g. GBIF maps show that T. officinale does exist in Finland (and neighboring countries), which can lead to confirmation bias, and even more misidentified observations…

2 Likes

I guess it all depends on your concept of a species. I have trouble accepting apomictic lineages as different species. A way that iNaturalist has dealt with this in the similar situation faced by blackberries is to have a “Rubus fruticosus complex” category.

2 Likes

This is a good discussion that gets at the heart of what taxonomy is all about. It’s cool to have a forum like this outside of academia where people can talk about this! Part of the reason I really appreciate what iNaturalist is doing.

7 Likes

Would a decent compromise be to apply ‘Sections’ as classification schema on iNat? I think that would at least foster more awareness of this group and perhaps even help the taraxacologist sort things out. I get the challenges of assigning species ranks to apomictic lineages but still think we could do better than calling everything Taraxacum officinale.

1 Like

@plantarum ?