This summer, I finished Philip Ball’s Branches. This is the last volume of his excellent Nature’s Patterns: A Tapestry in Three Parts, following Shapes and Flow. Branching phenomena are ubiquitous in nature. Apart from trees themselves, we have lightning:
And river systems:
And mineral crystallisation patterns:
Ball does a very nice job of explaining why these (and similar) branching patterns exist, as well as providing a good discussion of network structures. A fun little book, which I heartily recommend.