Zoe Schlanger - The Light Eaters. Buy this yesterday. It's so fucking good. All the current science on plant communication and neurology. The Factually podcast did a good interview with the author recently- https://www.youtube.com/watch?v=eBToVPeuHX0
Michael Pollan - The Botany of Desire. Pollan is better known for his How to Change Your Mind book about psychedelics, but this a particularly good book on four materialist histories of plants.
Matt Candeias - In Defense of Plants. It's kind of like a broader version of The Light Eaters with a focus on plant behaviour.
Richard Lewontin - The Dialectical Biologist. This and Biology as Ideology did more for me as a scientific horticulturist than any particular book about plants. To understand a plant, you need to understand the dialectic of organism and environment because a plant is intrinsically tied to one setting it mediates its whole existence around. The biggest thing that will hinder you in plant science is the way it isolates the subject into an object of study, trying to remove as many of the variables as possible. But plants exist as a product of endless variables and The Light Eaters shows that we've barely scratched the surface of their world or how it works. The more nuance you can build into how you approach plants- the ecology, the chemistry, the soil-atmospheric interfaces, the ethnobotany and anthropology, the environmentalist theory- the better you'll understand them. Botany on its own is pretty narrow.
