The iNaturalist species identifier is astoundingly good. Of the dozen observations I've made with it over the last few weeks all but one were spot on -- and the last one did have the proper species within the "don't know but might be one of these" list.

Flowers, trees, moths, mushrooms, and bees all properly identified for one or two images.

It works well with birds, too. I imagine it'll only get better as the database grows. Also, there's an army of volunteers that will usually confirm your observation within minutes.

I tried this app with ten photos of flowers; all taken in the controlled setting of a botanical garden. Not one of them was correctly identified!

The Botanical Garden setting could be part of the problem. The article says that your location is weighted into the results, considering past occurrences of species found near you. If you tried non-native flowers to the garden, it could have been weighted incorrectly.