How to Overcome Branch Disagreement

Platform: Website

Browser: Firefox

URLs of relevant observations or pages:

Screenshots of what you are seeing:

Description of problem:
I have a question about how the ranking algorithm determines the community taxon, since I’m not sure it’s handling disagreements as intended. Before I added an ID to it, the observation I linked to above showed up while I was searching for Plants with status Needs ID and a minimum Rank of Kingdom (so, labeled as belonging to Plants, but not more specific than that). The history of the observation, which you can see in the screenshot, is as follows:

  1. The observation’s owner accidentally selected the wrong species with common name “Milkmaids”.
  2. Another user disagreed with “Milkmaids (Burchardia umbellata)”, labeling the observation as Kingdom Plantae.
  3. The observation’s owner corrected their mistake by selecting the intended species name (Cardamine californica).
  4. A third user agreed with the observation owner’s corrected ID.

At the time I got to the observation, I figured that because it was still labeled as Plants, I could add my ID (Family Brassicaceae) to make it more specific, and then I moved on. The observation’s owner later contacted me to ask why I had brought the observation back to the family level, thinking that it must have been at the species level before. Looking at the About text under Community Taxon, I started to understand their confusion. The last sentence of the text says: “For the identified taxa that have a score over 2/3 and at least 2 identifications, choose the lowest ranked taxon.” Before I got to this observation, it had a 2/3 majority identifying it down to species, but it was still labeled with the coarsest ID of the 3: Plants. This conflicts with what I’ve seen on other observations with two specific IDs and one unspecific one, such as this one:

Is the disagreement in step (2) what’s causing this behavior? It doesn’t seem right to me that an observation with a resolved disagreement would need more community support to reach a consensus than one that never had a disagreement in the first place. Let me know what you think!

yes. this is what iNat staff call a “branch disagreement”, which means it’ll disagree with any descendant taxon. my take on the situation is that it’s a misapplication of the disagreement by the identifier, but some people like to use it in this way. a good identifier choosing to use the disagreement in this way should be receptive to removing the identification with the disagreement if you ask for that specific action to be taken. (if that identifier doesn’t respond, you can always ask a prolific CA plant identifier like @arboretum_amy to help tip the balance on that observation, if needed.)

that said, there’s not really a bug in this situation because the system is working as designed.


Welcome to the forum!

Yes, as @pisum noted, this is not a bug, but a branch disagreement. The disagreement at Plantae essentially functions as a disagreement to all taxa more specific than Plantae.

There are some threads about this on the forum like:
which includes some examples similar to the one you posted, though you can search for other threads too.

I’ve moved this to General and retitled since it isn’t a bug.

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To be more specific, a ‘kingdom plantae’ branch disagreement only counts as a disagreement on any phylum tracheophyta ID; it wouldn’t count as a disagreement on a red algae ID! I think this is kind of unexpected behavior sometimes and it can sometimes (rarely) enable observers to play weird games where they keep switching around the descendant taxon ID (maybe they’re just honestly confused, I don’t know).

do you have an example of this being the case?

That is Hard Disagreement.
Which iNat treats as - you disagreed with the previous ID - therefore you disagree with all subsequent IDs. Despite not having even seen them! This is not logical, and goes against iNat’s ‘be kind’ ‘presume that others have good intentions’

The identifier disagreed with the previous ID. End of. No logical reason to make that - I HATE all the things!

Rant over.
I have a workaround.

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Thanks, @pisum and @cthawley. I wasn’t sure what search terms to use to look up this situation on the forum, but @pisum’s mention of branch disagreement brought me to this blog post:

I agree with @pisum that the situation above is probably a misinterpretation of the disagreer’s ID, and it seems like the proposed changes at the end of the blog post I just linked to would be more intuitive. (It says the changes are planned, but it looks like the post was made 4 years ago. What’s up with that?) As the paradigm stands, though, I can ask the disagreer to remove their ID from the observation in question now that the disagreement seems to be resolved.


I just saw that you added your ID to the observation in question to help out. Thanks!

I will withdraw when I am notified of a 4th ID to the right species.

Sure, here is one of that exact scenario specifically (in reverse):
If the plantae ID had disagreed with Phylum tracheophyta and not just Phylum Rhodophyta, then the community taxon would be plantae, but it is pinales, as I described.

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