I am sad that you are not pleased with your botanical garden. Volunteers do the best they can and they work for free.
Well, no matter what the identity of the plant, you probably need to address the issue of the infestation on the back of the leaves. It could be as simple as a type of mold or it could be insects. You can try washing away the spots with a spray of water. If you are able to take very close photos so we can clearly see what is on the leaves, we might be able to identify the culprit.
Good luck with your plant.
