Actually, I saw quite a bit of taxonomy stuff on my DAT, and more plant stuff than I would have expected. Both subjects are not my favorites, but I used the Kaplan book with Campbell. I like the Campbell book (whatever edition), and complements kaplan well. I am no botanist, but knowing the underlying principles or plant function and familiarity with structures allows you to narrow the choices down pretty well, even if you get more of those questions than expected. But by all means I would not let yourself assume that plants, taxonomy, ecology will be too minor to focus on. If ya do, you will be sitting in the testing center cursing at yourself.