What is correct identification for a tree burl?

Tree burls can be caused by a number of things.
Here is the ones I know, feel free to add others I have missed.
wound (including those from animal claws)

Some of the more distinctive growths, can be identified to a particular thing that caused the growth:
Bacterial Crown Gall (Agrobacterium radiobacter)
Poplar Budgall Mite (Canadian Forestry Service) (Aceria parapopuli)
Corky Bark Disease (Diplodia tumefaciens)

How should I identify burls that the cause can’t be determined?
The tree species?
I can’t seem to find any other identification in iNat.

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i either dont ID them, or am forced to leave them at “life” since theres no other common ground between a virus and an insect and a bacteria and a fungus

i hate it so i often just dont post burls for that reason

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With galls, I’ll add ID life and add them to one or more of the gall projects on iNaturalist, since they are usually distinct and have a specific host.

From your post, I understand burls are not as distinct? If that is the case, I don’t think there is an official stance, by my opinion would be:

  • If the observer has specified the observation is for a burl in the notes/description or comments, then they have made their intention apparent & it should be respected. The best you can probably do is Life (and maybe adding it to any appropriate projects that may exist).

  • If the observer has not indicated that they expect an ID on what caused the burl, you may arguably be able to ID as plant species and not be violating the observer’s intent.


In your opinion, what would I do if the observer has identified a burl as Chaga?

Is there the little icon showing their ID was a result of using a CV suggestion?

I’d ID it as Life and leave a comment inside the ID. Something like:

“The Computer Vision suggestions are sometimes incorrect. [Leave that sentence out if they didn’t use the CV]. This is not a chaga, but a burl. They can have various causes (animals, viruses, bacteria, etc), which unfortunately don’t fall under one ID, so “Life” is the best ID they can be given. Would you like to have this observation be for the plant instead?”


If you can clearly see it’s not it - add a disagreement, even without use of CV people love to call every grow a tree has with this species. If it’s not seen from the photo - leave a comment asking how it was ided.

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I really appreciate your work on these records, even though they are a “gray area”!

In such cases where all I can say is “it’s not that”, my response is “it’s not x [optional ‘because’ phrase], but I don’t know what it is instead” as I disagree to the best taxon level I can. Which for a burl would be Life for me usually.

BTW If a burl then gets a “can’t be improved” DQA tickmark and an agreement at Life, it would go to Casual. In that case it might be good to use an observation field to distinguish it as a burl observation for later retrieval by interested parties. But, I don’t know what a good field is for noting a burl. Anyone have a suggestion?

Edit, making my own suggestion to myself: Only one hit comes up in existing fields for burls, https://www.inaturalist.org/observation_fields/5937 so maybe I’ll just use that unless there are objections.


From an observer standpoint, if I have an inkling what might have caused it, I’ll put that on there and possibly duplicate the observation to have one for the tree and one for the burl-causing organism. Otherwise, I probably would just have the observation for the tree, tag it with “burl” and/or add a note “with burl” so I can find it in a search.

From an identifier standpoint, when I’ve come across these I’ve usually just added a comment saying it’s a burl (to give the observer some sort of feedback on their observation) and leave it unidentified since I’m not sure I can tell what caused it. Using “life” as a category and saying in the comment that it could be caused by a number of things from viruses and bacteria to fungi or insects seems like a good strategy.

On an unrelated side note, I have a crown gall observation and was amused by the fact that iNat offers sex annotation (male/female) for Agrobacterium. That’s just too funny.