Sorry, me, for the double post but...
On topic, Bakker does write with a healthy selection of botany books within reach and I have it from more than a few readers (some I know personally with degrees in forestry) that Bakker's tree knowledge is on point.
Wait... really? Why??
Barring some kind of deeply-entrenched, long-planned botanical super twist, I'd wager it is for worldbuilding purposes.
Having spent an obssessive amount of time creating my own fantasy world that is also (like TSA, presumably) intended to be at least kinda realistic and accurate to real life, something that hits you fairly early on is the task of actually describing the natural features of the fictional places one is conconcting. Given the pretty vast range of biomes and ecological diversity on display throughout TSA, and since RSB does in fact describe the flora of most of the wilderness regions he creates (I can't speak to accuracy, but I've certainly noticed the attention to detail here), then in order to have an idea of what sort of plants grow in what kind of climate, during what season, what they look or smell like, and their agricultural/economic value...well, a few good books on botany are kind of a requirement eventually.
Plus, RSB grew up on a tobacco farm, so I would think he was somewhat equipped early on with an appreciation for how important flora is to describing...almost any type of outdoor location. I mean, if you're describing a place that is meant to be relatively reminsicent of its real life counterparts, the two big parts are the plants, and geological terrain it is growing from -- which both kinda go hand-in-hand to climate and ecology, all of which will inform the worldbuilding eventually, even if one starts with a city or whatever and works backwards.
(I mostly just use the internet, but I wouldn't turn down a nice botanical encyclopedia)
