If you are in the database and you see a photo that is incorrectly placed, you can propose the image be moved to the right plant.
But what happens when you know the image is in the wrong plant, but you're not sure what the correct plant is? Well, we now have a bin of unidentified photos, and you can move images from a plant to the bin.
Here's the bin:
The bin of unidentified photos (Holding_space)
To use it, just go to an image, open the image full size and scroll down to the bottom and click on "Move this image to another plant".
Then search for "unidentified" and the bin will come up in the list of plants. Select that and you're on your way.
If you're in the bin and see an image and you know where it belongs, you can move it out of the bin and over to the correct plant using the same "Move this image" technique.
Additionally, if you have a nice photo but aren't sure where it goes, you can upload a new image directly into this area.
