Some Questions About How Taxonomy (for plants) is handled here

I have some questions about taxonomy, particularly, two plant taxa, and I’m not sure where to raise it, but the example highlights more general questions I have about plant taxonomy and iNaturalist.

Basically there are two separate taxa, Mediterranean Amaranth (Amaranthus blitum) and Purple Amaranth (Amaranthus lividus) and there is zero information on the pages that cites any taxonomic authority or source or explanation of why these are treated as distinct taxa. The wikipedia page (on “About”) on the one just links to the other. And my Plants of Pennsylvania book only lists one. And the photos don’t look visually different.

I want to know (1) how and where are the proper ways to raise questions about taxa here on iNaturalist? (2) are there any places I can find references, sources, or explanation for the particular classification scheme used here on iNat?

This is especially important when I am delving into plant ID in an area where there is uncertainty, controversy, and recent changes in the taxonomy. I.e. it’s important for me to know WHAT the iNat taxa is referring to.

The USDA Plants database does this in several ways…one, it lists the authority behind each binomial name…and then, it lists synonyms for each plant.

Is this information stored or available anywhere on iNat? Or is there anywhere I can go to sort this stuff out? In many cases, a scientific name alone isn’t enough to make clear what the name is referring to and I’m not sure how to resolve it. This Amaranthus case is an example…just looking at the iNat records it’s not clear to me (1) why these records are distinct (2) what authorities are being referenced (3) where I can go for information to resolve this and/or figure out how to distinguish the plants if they really are separate taxa.


A list of the taxonomic references the site follows is here :

Please note that ‘follows’ is a concept that requires understanding. It may be better stated as ‘uses as a starting point and reference’. Deviations are permitted from any reference, but they are supposed to be done, and documented with both scientific and iNaturalist community support (a prime example is sections of the fern taxonomy on the site are not aligned to POWO which is the plant reference used on the site as even POWO themselves admit it is not fully up to date currently).

Each taxon page has a ‘taxon schemes’ link on the taxonomy tab which lists various sources where the name is in use (not guaranteed to be complete). It also has a taxonomy details link where if appropriate (not all families of life have defined references) details about alignment to or deviation from the reference will be noted.

Please note that in particular the taxonomy reference tool is only a few months old, so all data is not yet complete in there.

As a general rule, the site will only accept a global site as a reference, locally oriented ones are not accepted.

Questions about the taxonomy of a particular entity are best done by using the flag for curation link on the appropriate species page and filling in the question/comments there (note the initial creation of a flag has character limits on the title, but once saved, you can add comments of unlimited length).

Some familiies of life (mammals, birds, spiders, reptiles among them - not a complete list) are defined as locked, which means that every species in the iNaturalist database is accepted by the defined reference, or a documented deviation is in place, and the reverse is true, that all species listed in the reference are present in the iNat database.

While plants have a defined reference (POWO), it is not locked, that alignment is a massive task, and curator resources to do it are simply not available…


Thanks much! This makes a lot of sense.

I wasn’t aware that POWO was used as the reference for iNaturalist. Is there any way we could perhaps make that clearer?

It seems a bit odd to me to use this as a primary reference, yet not have any link to it or written reference to it on the taxon pages.

I think a reference and link to their page on a given taxa could serve multiple purposes here. For one, it would answer questions like my question here before it was asked, thus saving everyone’s time. Two, it would give them credit (i.e. iNaturalist is building off their work and referencing it, I think credit is due and it is a bit…disrespectful perhaps to be building off their work without mentioning, referencing it, and linking to it, especially when iNat is already linking to wikipedia, natureserve, IUCN, and other sites that seem less central in the classification scheme) Like, as an academic researcher, using someone’s work without referencing it is a big no-no and is often a sure-fire way to alienate people, in some cases even a punishable offence depending on the nature of your published work…and in this case if iNat is basically just duplicating the whole taxonomy scheme from POWO…it would seem mandatory to have a written reference (at least in my value system!) Three, a link would be highly useful to users such as myself viewing the page and wanting to look up additional information without having to open POWO in a separate window and manually search for each taxa.

POWO was not used to populate iNaturalist, POWO itself is a younger site than iNaturalist is. A significant percentage of the taxonomy pages on the site were created well before POWO ever existed.

It may make sense to have the POWO link automatically added to the links listed on the About tab, why other taxon have their reference automatically added upon creation but not plants I am unsure , a site staff member or developer would have to answer that(I suspect it may be that other sites use a naming standard in their pages that allow automated matching , while POWO does not)

As I mentioned there is a link, under the taxonomy reference section.


Oh, I didn’t realize that POWO was more recent, that makes more sense!

Sorry, I was having trouble finding this but I found it…under Taxonomy -> Taxonomy Details. I might prefer it to be more visible, but now I know where to look on records for the future!

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Additionally if a new taxon is created now, with POWO, or any other location as the resource, then when completing the new taxa details, that source is supposed to be indicated and referenced as in here :


Sorry, just realized that is in Danish, not English, but the bottom right is where it is . ‘Kilde’ is Danish for source

POWO is used, but I contacted them about some changes I want to see (recently described taxa) and got referred to The Plant List, and eventually to the lists maintained at Kew. Kew’s lists seem to be at the bottom of this. That’s where to go to get new taxa added, it seems.

(Tropicos isn’t a source for iNaturalist taxonomy, apparently, and that’s reasonable because Tropicos simply lists all the taxa and links synonyms based on the same type specimen; it doesn’t choose which is the best name.)

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POWO seems as good as any other one source to use as an external reference, but it suffers many of the same problems as similar sites like The Plant List, in that changes in their own classifications are often obscure.

I have a problem specifically with many of the Kew lists that sometimes cite non-peer-reviewed publications for major taxonomic change (such as checklists or monographs, and when you read these, sometimes they have created new combinations with no further justification).

All that said, I’m happy with the way things are working, and having the ability to open conversations via flags and add deviations to the list seems a good way to go.


I didn’t mean that POWO is not a good source, just that it isn’t an independent source. Try to make changes there and you’ll get “Oh, we can’t change things, we rely on _____” just as from iNaturalist you’ll get “Oh, we can’t change things, we rely on POWO.” And you get the same thing at the next step. The buck stops at Kew, for better or worse.

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I think you might be referring to a different website. Plants of the World Online is run by Kew and I’ve contacted them several times to fix mistakes or make updates.

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I agree. I think a lot of their range maps too are inadequately sourced. For example, all of them they reference “KBD” = “Kew Backbone Distributions” and they provide a URL to a database…but…when you actually type taxa into the search box, you find that they have published a tiny fraction of the taxa for which they’ve published range maps.

So…the reference seems to be little more than an obfuscated hand-waving of their own authority.

I recognize that Kew Gardens are viewed as one of the foremost botanical authorities in the world. But…I think they could be a bit clearer if they’re really just referencing their own authority with no explanations. I wish they would refrain from citing something as a “source” for something, that is not actually published yet.

I am currently in the process of an extremely ambitious undertaking to build what I hope to be better-sourced, better-referenced range and distribution maps of species, along with their native and introduced status. It’s a big undertaking though.

I have contacted Kew about two things, but it was recently. One was a question and one was an update or correction to a range map. I have yet to hear back from them or receive any acknowledgement that they’ve received my email. But it may be too early; they seem to have an extremely ambitious project underway and I imagine they have their hands quite full!

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