Reddit reviews New Complete Guide to Gardening (Better Homes & Gardens)

Better Homes and Garden's New Complete Guide to Gardening. It's what you are looking for, easy to understand, and an illustration for every plant it describes.

I bought my dad this about ten years ago, and he has absolutely loved it. It covers all aspects of gardening--trees and shrubs, landscaping, flowers, food plants and herbs, soil--in great detail. My dad is a very avid gardener, but I don't think he's bought another gardening book since he got that one.