Warning: this question is a significant spoiler to the "Speaker of the dead"!
Lets talk about sex. No, not the ordinary one but that of the Pequeninos (Piggies) from the Enderverse, which have a bloody (ha!) complicated life cycle:
If I understand it right, on the Mother Tree live slug-like "little mothers" feed on tree sap, then when they are big and fat are transported by mature Piggies to a Father Tree that pollinates them. Then the Little Mother is put inside Mother Tree, and after a while a new set of slugs eats its way out of Little Mother. Those slugs live inside for a while and again fertile female ones leave the inside to live on the outside and repeat the cycle, why males and infertile females wait a little longer until they start looking like baby piggies then they join the slugs competing for the sap. After a while an adult males leave to join other "brothers" while infertile "wives" stay to take care of the mother tree. Then at some stage, during one of the bloody wars or during a ritual adult male is killed and from his corpse a new father tree grows.
Question then is how does the mother tree came to grow in the first place?