About those dandelions

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I’ve made no secret of my skepticism about the dandelion microspecies; but like a good scientist, I am willing to consider the evidence. On the observations page for Section Taraxacum, there are 126,751 observations. By far the majority are identified as Taraxacum officinale (strangely, the Taxonomy tab for Section Taraxacum says that there are 131,233 observations of T. officinale, which raises some questions). Nevertheless, the same observations page also says that 91 species have been observed. Therefore, I scrolled through the list of species on the Taxonomy tab, and opened each taxon page that had >0 observations. I went through one by one, looking at bracts, leaves, stems, whatever I could think of that might differ between species.

I’m not seeing it. Okay, there are differences in the degree of red pigment in the stem and midribs – there are many, many plant taxa in which that trait varies among individuals and/or under the influence of the degree of sunlight. Okay, some species have floccose hairs, others do not; but that would only result in two species if it is considered an important trait. Okay, there are degrees of leaf lobing – from broad leaves with shallow serrations as in Taraxacum sundbergii, to triangular teeth touching the midrib as in Taraxacum acroglossum, to lobes with long, narrow tips as in Taraxacum eudontum, or even nealy linear as in Taraxacum incisum; but by far the majority are basically the triangle-tooth type. I noticed that some have opposite lobes like Taraxacum acuitifrons, whereas others have alternate lobes such as Taraxacum alatum; I suppose that could be important, but even ading it to the other traits I mentioned, we still don’t have enough dichotomous choices to key out all of the microspecies.

The names are not very helpful, as they suggest more distinctness than is visible. “Reflexed-bracted” – many of the species have reflexed bracts. “Orange-flowered” – the flowers are a slighly more orangey shade of yellow than some others, but not so’s you’d notice unless you had another kind right beside it.

In the end, I only found these few which stood out to me as distinct enough that I would feel confident about identifying them:

All the rest, I would have put the glabrous or mostly-glabrous ones with few bracts as within the expected range of variation of T. officinale and been confused what to do about the heavily floccose ones and the ones with many bracts.

The reason why this is in General and not in Nature Talk is because I am trying to understand what is visible in those observations that allowed them to be identified as those species. Since very few of them are Research Grade, presumably the observers who know enough about dandelions to upload them as those species would appreciate having someone else who can second their identifications. Also, I get the impression that dandelion aficionadoes consider that many of the “Taraxacum officinale” are misidentified, and it seems likely that at least a few of those six-figures of observations show the right characteristics to be corrected.

For my educational edification, I went ahead and uploaded my own dandelion observation – my first and so far only. I didn’t take 5, 8, or 11 pictures like the observers of most of the other species; but I did take three.
Fist, the overall plant habit:

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Next, the backside of the flower head, since I know that bracts can be important:

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And finally, a detail of the leaf:

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(I have heard mention of the “first” leaf of the season; but most places I have lived, dandelions are evergreen, and it is hard to say when the season begins or which leaf is therefore the first.) Here is the link to the original observation.

So: based on these three images, do any specific species or microspecies come to mind? What is missing for you to rule out others? What are the minimum parts to photograph for an identifiable observation? To me, it just looks like officinale, like most of the putative species I looked at, but I am open to being persuaded.

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the 131,233 includes casual observations (missing location, date etc), whilst the observations page (with default settings) does not

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Here is a paper that a botanist friend of mine wrote on the subject, and a second one describing some new species:

https://cdnsciencepub.com/doi/full/10.1139/cjb-2018-0094

Abstract

In almost all North American literature, including in British Columbia, weedy Taraxacum species have been named as Taraxacum officinale F.H.Wigg and Taraxacum erythrospermum Andrz. ex Besser (or Taraxacum laevigatum DC.). This coarse taxonomic approach ignores great diversity in morphology, ecology, and geographical distributions among the exotic established species. Taxonomic refinement would facilitate floristics and ecological studies when exotic Taraxacum species are involved, and the taxonomy of native Taraxacum must first determine which are and which are not native species, which in turn requires knowledge of sectional identity of any specimen. Exotic Taraxacum specimens were identified to species and taxonomic sections using refined species and sectional concepts that align with taxonomic standards used in the native ranges of the species in Europe. Seven exotic sections and one informally named group are found to be present in British Columbia (Borea, Boreigena, Celtica, Erythrosperma, Hamata, Naevosa, Taraxacum, and the Taraxacum fulvicarpum group). The number of exotic Taraxacum species known to occur in British Columbia to date exceeds 100. A key to the exotic sections of British Columbia Taraxacum is presented and the sections are characterized. Species known to date are listed by their sectional placement. Notes are also presented on distinguishing native from exotic Taraxacum in British Columbia.

and:

https://pubag.nal.usda.gov/catalog/7366000

Five new species of North American Taraxacum (Asteraceae)

Author:
Curtis R. Björk
Source:
Brittonia 2021 v.73 no.1 pp. 116-126
ISSN:
0007-196X
Subject:

Abstract:
Five new species of native North American Taraxacum are described: T. argilliticola, T. cordilleranum, T. lautellum, T. pugioniferum, and T. simplex, all of them from high elevation habitats or high latitudes in western Canada, mostly from British Columbia.

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I’ve been exploring this for a couple years and have been stalled for a few reasons. For the same reasons, you’re not likely to get satisfactory answers here.

My understanding is that the author of the papers @ryan_durand mentioned is the only person in North America with useful experience with dandelion microspecies, and he wants to expand on those papers in the future but he’s busy with a lot of other botany work as well. There are a decent amount of people in Europe who are confident in their ability to identify microspecies within their countries, but they’re generally not interested in identifying North American dandelions because they have no idea what species options there are; the plant could have originated from anywhere in Europe and they only have experience with the microspecies in their own country. I’ve found a lot of resources for identifying sections/microspecies but they have the same issue; they’re only made for smaller regions of Europe so the applicability for North America is limited when we know so little about the options. Not many people with expertise are active on iNaturalist because it’s American and in English and they may have their own national biodiversity documenting programs, and even fewer use the forum.

Ultimately for iNaturalist’s taxonomy I don’t think it makes much difference what anyone’s opinion about the various options are. INaturalist curators aren’t supposed to create new taxonomy systems; we have to use existing ones. For plants iNat follows POWO, which rejects T. officinale. Additionally, iNaturalist needs a taxonomy that works globally. The two options we have are the Eurasian system, which is already global, and the North American system (FNA), which is outdated and not adaptable and taxa from other continents can’t be worked into it. I tend to be a lumper and I think the dandelion microspecies are excessive but I still think iNaturalist needs to be using the European system. If someone wants to do a ton of genetic and morphological work and publish a new global taxonomy that’s closer to “sections ~= species” that would be amazing, but it doesn’t exist now and I can’t imagine anyone wanting to do it. Currently on iNat we are using a messy mishmash of the two systems.

Relevant forum thread:
https://forum.inaturalist.org/t/overlooked-dandelion-diversity-in-bc-and-everywhere-in-north-america/3808
And flags:
https://www.inaturalist.org/flags/526232
https://www.inaturalist.org/flags/535033

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Well… POWO redirects “Taraxacum officinale” to “Taraxacum sect. Taraxacum”. Without looking at the nomenclature, as taxonomy that seems perfectly reasonable. Those of us who consider the putative species pragmatically hopeless—even if in fact biologically meaningful—can just call it a section and move on. Or we may as well stop at genus.

Arguably, that’s exactly what we do have—the sections are ≈ species. :-)

We could get hung up on rank, or we could just conclude that in Taraxacum “section” means the same thing “species” does in other genera. Just like we all deal with the fact that in birds and mammals, “family” means the same thing “genus” does everywhere else.

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Yep, e.g. @jasonhernandez74’s plant is section Taraxacum based on a quick look at the bracts (strongly recurved) and leaf structure (lots of lobes, 3-dimensional edges). Plenty of organisms can’t be identified below genus or section from iNat photos.

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If I encountered them more often outside the “lawn weed” context, I expect I’d feel obliged to pay more attention.

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@jasonhernandez74 – The one other photo for your set would be a close-up of the flowers, so we can see if there is pollen being pushed out of the tubes by the stigmas, i.e., whether the plant produces pollen.

I like the idea of working up identification methods for Taraxacum sections. That might almost be worthwhile. Meanwhile, I mail Taraxacum specimens to Bjork and label observations here as Taraxacum, then click “No, it’s as good as it can be.” I don’t worry about what name the first observer put on the observations because I don’t believe any of those names.

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In my opinion everyone who is interested in this general topic should read these four papers summarizing the revision of the genus Urtica, also known as “Nettles.” It is as though they were channeling you @jasonhernandez74 and had had enough.

Weeding the Nettles I-IV

Right now I can only find a free link to the second paper, “Weeding the Nettles II: A delimitation of ‘Urtica dioica L.’ (Urticaceae) based on morphological and molecular data, including a rehabilitation of Urtica gracilis Ait”

It feels like they said, “Okay, let’s approach this scientifically for once.” and instead of speculation and opinion about the amount of pigment in one midvein vs another, they collected seed from all over the world and grew what they could in a common garden experiment as well as using molecular biology and morphology etc.

Anyway, my first thought after reading your post was that someone should do this for dandelions.

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By the way. You can simply open list with all observations of the section without T. officinale by adding &without_taxon_id=47602 to the URL.
https://www.inaturalist.org/observations?verifiable=true&taxon_id=967514&without_taxon_id=47602

Shapes of seeds?

This is the answer I’ve got about dandelions from one expert.

Dandelions are complicated, some qualifiers even write about the need for observation throughout the growing season, because you need both the characteristics of the flower and the shape of the leaves, and the characteristics of the seeds, and even the absence/presence of pollen. Apomictus, after all. Often I have to either mark plants and then go back to re-collect, or (if far from the base) bring a micro-monolith with the plant and “ripen” the fruit.

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I’m a self-taught amateur/neophyte and I rarely venture outside of my home state (Nebraska) when ID’ing, so strictly speaking I personally wouldn’t venture a guess on a North Carolina observation. However, your questions seem more general in nature so I’ll answer as if your observation were from my own back yard (or at least from somewhere in Nebraska).

I generally rely upon the Flora of North America and The Flora of Nebraska. My synthesized understanding from both is that:

  1. Taraxacum officinale is definitely present throughout Nebraska.
  2. Taraxacum erythrospermum has been recorded in Nebraska by various authorities but is often difficult to distinguish from T. officinale. The authors of Flora of Nebraska don’t list T. erythrospermum under its own entry but as a note under the entry for T. officinale, where they add that “[they] have not seen Nebraska plants that are unequivocally T. [erythrospermum].” Apparently the color of the achenes is the most definitive distinction between the two.
  3. There are very possibly other species of dandelion present in Nebraska considering the recorded flora of the states adjacent to us.

So were I to observe or ID these in particular I’d put them at genus Taraxacum and then, like sedgequeen, click “No, it’s as good as it can be.” Were the achenes more visible, in good, apparently “true” lighting, then I’d venture into ID’ing them to the species level, either T. officinale or T. erythrospermum, all the while thinking I wish dandelion taxonomy was less convoluted, and suppressing the nagging thought that it could be one of the other species of dandelion that are possibly present in Nebraska.

So for me in my area I’d consider the minimum parts to photograph being (1) the general form (leaves, stem, inflorescence, etc., don’t need to be real close up though) to the extent necessary to confirm it’s a dandelion and not some similar-looking member of Asteraceae, and (2) to get to the species level, the achenes. Rightly or wrongly, I don’t generally worry about the bracts but can imagine that it’d be more necessary for a wider geographic range, or were I to want to truly rule out with 110% confidence that what I’m looking at is not one of the “possibly-present other species”.

EDIT: If someone were to argue that, despite not being able to see the achenes, it is still quite likely that it’s T. officinale, I’d agree. However, saying something is likely a thing and confirming that through observable traits are two different things, and only the latter makes me feel comfortable when helping to push something to research grade.

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Bjork told me that seeds are important in section Erythrospermae (red-seeded dandelions) but not so much for the introduced weedy dandelions in section Taraxacum. (Introduced in North America)

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For what it’s worth, most robust species delimitation studies nowadays incorporate at least one other data type (usually morphology or ecological data), the molecular dataset they’re using is pretty limited for addressing population scale questions (which species delimitation studies often turn into), and concatenation isn’t a particularly good phylogenetic technique compared to more modern techniques that use multispecies coalescent models. I don’t think it affects their conclusions that badly, but my point is there are some better papers out there you can read if you’re interested in how species delimitation works.

As for Taraxacum, apomixis (asexual reproduction) can really throw a wrench in species delimitation. If you apply the biological species concept (and to some degree, phylogenetic species concepts), every individual is basically an independently evolving species. Even under the general lineage concept (probably the most universally accepted in the field), you run into the problem of defining what a population or metapopulation is. Under these circumstances, there is an arbitrariness to where you draw the line if you can’t come up with some other criteria (such as morphological distinctiveness). Unfortunately, these other criteria can be equally arbitrary.

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Why isn’t there a Taraxacum officinale complex ?

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@serpophaga I predict that you will be interested in this discussion.

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I don’t know but I can think of two good reasons why. First, Taraxacum section Taraxacum is a good approximation of a Taraxacum officinale complex. Second, we use complexes when multiple species are not usually distinguishable from photos on iNaturalist, and ALL dandelions are not easily distinguishable from photos, so there’s really not much point in setting up a complex for them.

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so should I be marking dandilions as T section T then? As a non-plantsy-person is the the best? Ive just been doing Taraxacum for now, I ID in Alabama.

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I already figured that. I don’t recall ever seeng a dandelion that wasn’t Section Taraxacum. That is why I limited my research to those species in Section Taraxacum. I think you are right, that I am not going to get satisfactory answers here; I presented that plant as an example of Section Taraxacum (a.k.a. Taraxacum officinale) with the idea that it must, presumably, be in one of the microspecies that people say comprise that section.

Okay. Apomictic vs not. Is there a source that would tell me which lineages are apomictic and which are not?

All very well, but it doesn’t help at the level I was trying to consider, namely, observations already considered to be Section Taraxacum. And this is part of what contributes to my skepticism: that virtually nobody can get beyond section. Just as asipdoscelis noted:

…which, for all practical purposes, is tantamount to concluding that “Section Taraxacum” is Taraxacum officinale. And I hate to say this, but the answers so far tend to suggest that I should just go with Taraxacum officinale and not get pedantic about it being a section.

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My point precisely. :-) It’s not obvious that these are meaningfully different taxonomies, vs. “let’s just shift everything up or down a rank”.

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There is. “Taraxacum”. :-)

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