What eulemur wrote. We can stick trees into the ground up to their tops to create bushes, we can plant flowers under water to create see weeds, we can rotate trees and place them upside down, if we want.
Nope, botany will be of no concern in Planet Zoo - and while I am a big fan of anything plant-related, in this case, I am very happy about it! The freedom of creativity is way more valuable than an over ambitious botany simulation in a game about animals. (Imo, always just imo!)