Maybe onboarding could include phrasing like this:
“While you of course will have limits to how much you can show, in the number of photos, or other kinds of information you can give in your observation, know that the identifying features of a plant, animal, or fungus can occur on that plant, animal, or fungus, as a whole, or on any of their countless parts, as well as from their habitat, potentially sounds they make, or even smells they have. As your post invites people to give their identification of your observation, consider offering the identifiers views of multiple parts, maybe different angles, possibly different distances, and showing / highlighting multiple features, which may include the features they need to identify it. One photo might give views of more than one part, or you might offer additional photos to give views of additional parts.
One photo of the face of a flower, won’t show many of the identifying features of that plant species, when a botanist may need to at least see other parts, such as its lowest leaves, or get a view of the whole plant, to identify it. One photo of looking down at a mushroom may not offer enough identifying features to the mycologists. Fungi have critically important identifying features on both their tops, bottoms (usually their spore-bearing surface, such as gills, or pores), and often their sides. Similarly, one photo, looking down at a whole snake, may miss key identifying features for the herpetologist. A snake might have scale patterns in their face that are key to identifying them. So think about offering views of a set of multiple features, often in more than one photo, and possibly telling about potential identifying features in comments in the “Notes” section. If it would be practical, including a recording of a bird, or insect, might clinch an ID for an ornithologist, or entomologist. So try to give a set of views, and any other information, that offer multiple, different, possible identifying features, to identifiers, that may have learned to identify that species, or that group, by one, or more, sets of different features.”