Semiosis by Sue Burke

Pretty nice exploration of plants and evolution. It suffers from some typical novel problems - characters don't really talk to each other or explain things. It also portrays humanity as being willing to live together with huge, lethal, bug creatures and get along with them fine, which seems unreasonable.

Also, using scents for battle tactics seems like a problem for the alien species - compared to light/sound, its transmission is much less reliable - wind, lingering scents etc are all problems which don't happen for light/sound.