My favourite books are references that read like stories, instead of a textbook that has all the information there to hand when you want to find it but one that you read through and learn as you go.
Botany for gardeners is one of them; Brian Capon writes the full process in which plants develop, explaining in detail in a way that an amateur botanist can fully understand. You obviously don’t learn everything but do learn a lot more than you would think you needed to know as a gardener. I believe understanding botany makes a better grower and so highly recommend this book.
The other is off topic but similar in its approach; Shell life on the seashore by Philip Street, being a complete mollusc novice this book has taught me so much about shelled creatures and the environment they inhabit. Again he writes in a storytelling way passing on his knowledge in an approachable way.
How do you like to learn? Through textbooks and references, short articles or novel like non fiction?