Taking
Daylilies for instance, if you look at that list, you see that many entries do not have images. The database photos are all submitted by members like you and I so the entries with missing photos just means no one has added any photos yet.
And say for instance you have a daylily but you have no idea of the cultivar/variety name, you can add your photo to the generic daylily entry. It's that very first one at the top of the list.
