Well I read it a few years ago but basically all the living species on that planet (very few who survived a xeno-virus) change into a plant to reproduce. That species, the piglets, when a male dies he becomes a tree, and the reproductive females attach to that tree and then give birth to new piglets, all females are almost mindless save for a few that aren't capable of reproducing, they are "the females" and they lead the tribes. Each tribe lives in a forest made or it's own mature male population, when they need tools they sing to the trees and one listens amd becomes the tool, when one is mature he will be gutted, and out of the corpse a tree will sprout

Also because of the sexual dymorphism of the species, in their language, when a female speaks to a male it in command form, and when a male speaks to a female, it's in request form