Sections for Euphorbia

How do people feel about adding sections (or subgenera) to the genus Euphorbia? I'm not completely sure if it would even work. But if I could figure it out, I'd be interested to know what other people's thoughts are. This would be a way of maintaining Chamaesyce (as sect. Anisophyllum) and Poinsettia (as sect. Poinsettia) as a distinct from the rest of Euphorbia (and others potentially) in a way that is more in line with current research. I know it would be immensely helpful for me to put the species into more manageable groups. Also, I think this would be nice for those who dislike the idea of losing Chamaesyce (myself and many others I've talked to). It's actually a bit difficult to bring myself to make a taxon swap simply because I know that iNaturalist won't maintain the distinctions.

The Flora of North America treatment will include several sections and a few subgenera when it is published (sometime later this year, apparently), and I would add taxa based on their classifications.

Let me know what you think.

Posted on September 09, 2016 02:59 AM by nathantaylor nathantaylor


Subgenera... Whew... Well, I'm adamantly opposed to subspecies, but I've not really thought about subgenera. ;)

Does this distinction exist on iNat? I know that for bugs, they have 'tribes' but I think those include several genera...

In all honesty though, you curate this group so wonderfully well, I'm totally ok with subgenera of Euphorbia! Not everyone is so dedicated when a change like this would be made. :)

And yeah, I miss Chamaesyce., too. I hardly knew ye, Chamaesyce...

HOPE you're still planning on coming to the Big Thicket in October!!!! There would be several folks that want to meet you (@gcwarbler and I talked about you in Big Bend).

Posted by sambiology almost 8 years ago

I'm all in favor of adding the generic Sections, as long as a search for either "Euphorbia whatever" or "Chamaescye whatever" BOTH are found by the database search and lead you to the same taxon.

I suppose this would count as (i.e., be accomplished by) a Taxon Swap. Each species would simply be renamed something like "Euphorbia [Chamaescye] whatever", "Euphorbia [Pointsettia] dentata", "Euphorbia [Tithymalus] roemeriana". Would that be the intent?

Sounds like a lot of complicated curating! Check with @kueda and/or @loarie, to see if that would be kosher.

Posted by gcwarbler almost 8 years ago

my main concern is whether all genera in Euphorbiaceae can be assigned to a section or not. If they can, then I don't really see a problem but would love to see the source. If they can't then it can really screw with how the iNat ID system leverages the taxonomy hierarchy.

For example. Imagine we currently have Euphorbiaceae -> [genus A, genus B, genus C]
and these fall into sections A and B like so:
Euphorbiaceae -> [section A -> [genus A, genus B], section B -> [genus C] ]
but for whatever reason no one moves genus A so we end up with
Euphorbiaceae -> [genus A, section A -> [genus B], section B -> [genus C] ]
then if I ID something as section A and you ID it as genus A, iNat will think genus A disagrees with section A when in reality genus A should be within section A so it wouldn't be a disagreement
Unfortunately, since the taxonomy is global, even if all US genera could be assigned to section, the above problem would still happen unless all Ephorbiaceae genera could be assigned to section, but I don't think this is the case?

Posted by loarie almost 8 years ago

I'll echo what Chuck says, "I'm all in favor of adding the generic Sections, as long as a search for either "Euphorbia whatever" or "Chamaescye whatever" BOTH are found by the database search and lead you to the same taxon." It's not totally the same, but why can't you just introduce new names for the existing taxon -- so Chamaescye maculata would lead the ID to Euphorbia maculata, etc... Euphorbia maculata would still be the name that iNat uses, but now you've included the other genus to aid in the search for the taxon.

I think trying to break up the one genus into subgenera would be a bit sticky to curate... It'd open up the door to introduce LOTS of subgenera for the other massive genera (look at you, Asteraceae). Those are just my two cents, but my pocket change has been leading me to becoming more of a 'lumper' though. :)

Posted by sambiology almost 8 years ago

ugh misread - I thought we were talking about subfamilies not subgenera. My same above concerns apply to subgenera as subfamilies but one additional one.

If you add a Section, it still won't change the binomial, e.g. adding Euphorbia blahblahblah to Chamaesyce the species binomial would still be Euphorbia blahblahblah as in
Genus Euphorbia -> Section Chamaesyce -> Species Euphorbia blahblahblah
So if you wanted to search for Chamaesyce blahblahblah and get back Euphorbia blahblahblah that wouldn't happen by adding sections and could be handled just by adding some invalid taxon names (e.g. Chamaesyce blahblahblah to Euphorbia blahblahblah)

Posted by loarie almost 8 years ago

Thanks for the all the helpful comments (especially loarie for the technical advice)! I'll continue to read the comments as I'm not sure I quite understand everything yet and I'll be sure not to do anything until I both understand and get the ok here.

@loarie the group that used to be the genus Chamaesyce is now sect. Anisophyllum. If I were to search Anisophyllum in the species box, would it act like the other taxa and give Euphorbia sect. Anisophyllum along with the species under it? As far as I know, genus Anisophyllum doesn't exist (at least, legitimately) and there are some plants that have the specific epithet anisophyllum (none appear to be listed on iNaturalist yet, but Galium anisophyllum and Asplenium anisophyllum are the two I have found so far). Also, if I understand it correctly, I would have to change the parent taxon of every Chamaesyce species individually to E. sect. Anisophyllum. Is that correct?

I think I could get all the Chamaesyce species that are currently on iNaturalist (and most that are known to science), but would have a hard time getting those outside Chamaesyce. Would it cause problems if I implemented only one section? Right now, I have sources for sect. Anisophyllum for much of the world, but my main "blind spots" are in Africa and Australia (Australia because of paywalls). If I did this, I would add every unsynonymized name I could find to sect. Anisophyllum and add Chamaesyce as a synonym for sect. Anisophyllum. The nice thing about Australia is that there are plenty of websites I could use in the meantime for names. Africa would be more difficult.

The main reason I would like to have a section or subgenus added in is for grouping. I could technically search all the species in sect. Anisophyllum whenever I wanted to look at the group as a whole but it's difficult with over 300 species worldwide (I'm not yet sure how many are represented in iNaturalist but it is probably at least 100 as searching Chamaesyce gives 137). With around 2000 species in Euphorbia (853 currently added to iNaturalist) as a whole, it's difficult to wade through the large numbers to find the species I'm interested in without typing out the species names individually. Also, not all species in the Chamaesyce group have the synonym Chamaesyce (e.g., E. jaegeri) making it even more difficult. I have created tags for different sections and subgenera but these extremely time intensive to apply. I'm planning on making one or more Euphorbia projects at some point (I'm thinking one for the United States and one for Mexico at this point, but am not sure yet) and having a way to separate the different groups would be very useful.

Posted by nathantaylor almost 8 years ago

this is one of the things that is so frustrating about plants, that there's no global list. There is The Plant List, but even the Kew folks who made it always tell me its got issues and not to use it. Interesting that it has not lumped Euphorbia, Chamaesyce etc.

I guess the issue remains that if someone observes some random Euphorbia that occurs in Asia (Euphorbia blahblahblah) we know its in the genus Euphorbia, but how would we know what Section its in without a global list of which species are in which section?

Posted by loarie almost 8 years ago

It's interesting (and somewhat comical) that the plant list holds onto 4 species of Chamaesyce. I guess these got overlooked somehow. I know the C. inaequilatera has the wrong author combination ( Hopefully, I'll be able to get all the species in sect. Anisophyllum together.

Knowing what section a Euphorbia is in might be hard (someone more experienced in Euphorbia as a whole might be able to do it), but knowing if it is in sect. Anisophyllum is fairly easy. It is the only group that has C4 photosynthesis and has several other characters that go along with it, like Kranz Anatomy, asymmetric and opposite leaves, dorsi-ventral stems, and sympodial branching. That's part of why section Anisophyllum used to be a genus. If a Euphorbia was found in Asia, I would be able to tell if it was in sect. Anisophyllum or not by its characteristics. Morphologically, Chamaesyce is a well-defined group. The problem is that Chamaesyce (as well as Poinsettia, which is not as well defined) is nested phylogenetically in a much more morphologically ambiguous Euphorbia. There are 4 major clades in Euphorbia and the clade that includes the Chamaesyce group also includes Candelilla, members of Poinsettia, and many other Euphorbias.

Posted by nathantaylor almost 8 years ago

Starting with Anisophyllum sounds like a good idea

Posted by loarie almost 8 years ago

Sounds good to me. Only adding section Anisophyllum would be a lot more manageable for me. I was thinking of the other sections mostly for completeness, but I'm currently working only on sect. Anisophyllum so it really isn't all that important to me to add other sections. It might be nice if I could do the others eventually too, but it would definitely be better to wait on those now that I have a better idea of what all is involved.

@sambiology and @gcwarbler , does this sound agreeable?

@sambiology , Thanks for the reminder about the Big Thicket. I had forgotten. I'll let you know soon.

Posted by nathantaylor almost 8 years ago

@nathantaylor7583, sounds great to me. As long as you come to the Big Thicket. That's the only way that I'll allow this sort of curation. ;)

Posted by sambiology over 7 years ago

As with any iNat decision, I'll go with the consensus. I share @nathantaylor7583's frustration with a few of these large genera, including the newly expanded (ugh) Oenothera (Onagraceae).

Posted by gcwarbler over 7 years ago

I've got all that I could find for today (and all from the US, except two that I'm waiting for their resurrection in print). I ended up with a total 113 species (not including subspecific taxa). There are still a lot to find as I only found about 4 "old world" species and only one Australian species. It looks like I have a lot of species to add, as the count for sect. Anisophyllum is somewhere around 300 right now.

Posted by nathantaylor over 7 years ago

i got mixed up on this one because unlike with a regular species, the genus is displayed. So I added a coarser ID without meaning to. is it possible to change it to something like: "Euphorbia subgenus Anisophyllum" so one can see at a glance it is in the euphorbia genus? Not a big deal but when i am looking through observations and see something in the Euphorbia genus and see another word there my brain says 'wrong, need to change to euphorbia' even though that isn't true.

also... i really would love to have the sedge subgenii added... but i don't have time to try to figure them all out especially globally, so i guess i have to hope someone else wants to. especially since i am no sedge expert

Posted by charlie over 7 years ago

So, I tried to changed the view and ran into a couple of problems. First, I typed in "Euphorbia sect. Anisophyllum" and the period in "sect." disappeared and "Anisophyllum" was no longer capitalized. Second, there is no selection for sections. I currently have it at subgenus since it is a required field and that was the closest taxon I could get, but it isn't correct and looks a bit odd.

I think the format was different before as I remember trying to get it to view this way but couldn't. Since I was able to type in the taxon, I typed in section. Any advice on how to resolve this? Here's the link:

Posted by nathantaylor over 7 years ago

My personal preference is to have the uncapitalized version with the genus but i don't feel strongly about it

Posted by charlie over 7 years ago

sorry to be so late to the party, but I'm curious what became of this...

Posted by astra_the_dragon almost 4 years ago

Which part? I honestly can't remember many details about this at all, but I did end up adding sect. Anisophyllum to iNat taxonomy. I've added more than that too. I think most if not all the iNat Euphorbia species are under at least subgenus if not section now. Subgenus Chamaesyce (if I remember correctly) is completely integrated (including all of its sections). I think I also did most of Athymalus and Esula. Subgenus Euphorbia is large enough that I haven't attempted all the species yet, but I think the sections that have been treated as separate genera would be fairly easy to finish integrating if they haven't been already (e.g., Crepidaria and Monadenium). I may have done Nummulariopsis too, but I'd have to look back at my notes.

Posted by nathantaylor almost 4 years ago

Yup that's basically what I wanted to know. Thanks!

Posted by astra_the_dragon almost 4 years ago

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