Announcing, an ID guide for plant galls in North America

I’m excited to announce that our new North American gall ID website,, is ready for public beta use. We’ve been working hard on it for months and we’re finally ready to share it with the iNat community.

We’re still in the process of building our database, and some features of our site may still be improved. Here’s what you can do now:

  1. Use our ID tool to identify over 500 galls on oaks (in the eastern US; California in progress) and hackberries

Our ID filter allows you to filter by host species and location on the plant, compare images, and read primary literature to confirm and compare IDs.

  1. Give us feedback on the site

It was made for iNat users, and we want to make sure that the experience of using the site is clear and convenient for you.

  1. Help us fill out the database

We estimate that there could ultimately be something like 5000 entries if we manage to cover every plant gall known from the US and Canada. We’ll never get there without help. This requires NO prior knowledge, only curiosity and some free time. We can help you find primary lit sources, and as you transfer them into the database, you’ll become the expert.

We’re also still looking for other kinds of support. If you have experience in web design or programming, there are lots of things to be done to improve the site.

If you’re interested in joining us, you can join our Slack channel here.

PS: Thanks to everyone who’s licensed their images as CC or public domain–we’ve been relying heavily on these to illustrate the galls. The site wouldn’t be nearly as useful without them.


Great Stuff!


Oh, that is so great! Wow! Those hackberries are odd bunnies!

I’m looking forward to checking it out further. Thanks for offering this resource.


This is amazing! Really great stuff and finally a resource for those of us that find a gall and have no idea for where to even start. Thanks so much.


Looks fantastic! Instant add to my bookmarks. I really like that there is an option to search by gall or host. Thanks for putting this together!


If you are tech savvy and want to help us out we would definitely welcome the help. The source for the site and all of the data is on GitHub.

Something that I definitely could use some help with, is design/UX: creating a logo, an improved color scheme, as well as other UX issues.

I am really excited for people to start using the site!


Awesome! Being able to search by host plant makes things so much easier.




That’s a great effort! Do you think it would be useful to have a “gallery mode” in the Explore mode?



This is an interesting idea. Explore mode is pretty half-baked at this stage and we have been unsure where to take it but this may be an interesting avenue to make it more useful.

This is awesome, congrats so far!!

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I’ve been waiting for a site like that for years. And I see one of my photos, too!

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This is so valuable. Feel free to use any of my photos.

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Looks neat. What’s the difference between a Detachable and a non-detachable gall? All galls I can think of seem pretty firmly attached to their host plant. Does this perhaps mean whether a gall forms around the host plant (e.g. Cherry Black Knot) or on top of it (e.g. Cherry finger gall)?

In short, can you remove the gall without cutting or ripping the plant tissue it’s attached to. There are some borderline cases but it should mostly be pretty clear. Eg this is an integral stem gall while this is a detachable leaf gall.


Thank you. On the main website page, it mentions the long-anticipated update to Russo’s guide. Note that this is now available.

Very nice. Used it to attempt ID. Seems probable.

Bonjour @ Megachile. Vous pouvez utiliser toutes mes photos, elles sont toutes dans le Domaine Public.

Beau travail. Merci


Je suis venu sur votre site pour identifier des galles observées sur Salix eriocephala, mais cette espèce ne figure pas sur votre liste des genre “Salix”. Est-ce un oubli ?