It's very unlikely. The "click and drag" to draw a box works great with a mouse but the phones and tables register the finger press as a click. I may figure out another way to do it but for now it's a desktop only feature.
Still even if the person is unable to add labeled boxes on their photo, they could list the names of prominent plants in the photo in the comments section. Then if someone is interested in a certain plant they can look it up in the database.