Books don't work for things like this. Where are the papers? Start with actual science, exhaust all avenues on that and then the philosophy can be approached.
Each of the above-linked books is filled with citations, including dozens of other researchers' papers. Start with general philosophy, exhaust all avenues on that and then the "scientific" can be approached.
Perhaps you can share some of the more relevant links so there many of us who aren't interested in buying entire books can check them out. Unless your purpose here is to promote said books, in which case I wish you luck.
It really doesn't make sense to start with philosophy as there's little to no grounding data, and philosophy is vast; essentially limitless. Science is required as grounding so the study has a foundation and discussions can be properly scoped.
This is my favorite "intro thought provoker," which I have seen several great authors comment about (I am not a scientist, but I'll do my best at the citation format):
Shomrat, T., Lemma, M. (2013). Memory through regeneration in planaria? Journal of Experimental Biology. [this paper details training planarians to navigate a rough surface for food, decapitating them, allowing heads to regrow, and demonstrating that the trained behavior reappears after regeneration].
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I'll look for a more plant-specific citation (of course: these were the "reaches" from author Pollan's book in my original comment) – then replace it here. The researcher is Stefano Mancuso, a plant-neurobiologist.
Gagliano, M., Mancuso, S. (2014) Mimosa pudica learning and memory. Oecologia, 175, 63-72. [experience teaches plants to learn faster and forget slower in environments where it matters]. == "pea plants solving mazes" study
Slime molds are an incredible & additional entire. nother. world.
If you watch documentaries: Netflix's non-fiction My Octopus Teacher will make the most grizzly of bears weep... so beautiful, this world.
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I'll admit: some of the credentialed scientists seem like "modern-day kooks," certainly... but: nobody else seems to have a better explanation for THIS [0].