I have no idea what a master gardener is (a US thing I guess?) or why I would care if they endorse an app. But I have tried a couple of the top rated apps for this on Android and found them utterly terrible. I remember one result, I took a very clear photo of a bunch of bananas growing on a tree and got some kind of ferns as the answer. If this app can do better I expect there's a place in the world for it.