It's almost as if it's by intelligent design ...

Not really.

You and your wife are in the same boat I was in just a few years ago when I moved to a new area and knew nothing about the plants here. As a result, I put together some material for my own use, shared them with others, and have had requests to put those resources up on the web. I hope you might find the site suggested below of some use.

Here is a link that might be useful: Learn Plants Now

I'd suggest a book titled Hortus Third. I've had this book for 32 years. It doesn't have any frills, just black and white drawings of the plant parts for most of the plant families. It looks like a big dictionary (and it is, of plants) and if you aren't serious about plants you won't use it. When you look up a begonia it'll tell you why it's a begonia and the differences between the species and cultivars. Anita