The Parliament of Trees, although not composed of the first elementals, still predated man by many years and were founded by Alec Holland (better known as Swamp Thing) when he found himself continuously thrown back in time. He planted the seeds that would become the Parliament's founders: Yggdrasil, Tuuru and Eyam were the first three members of the Parliament. All the members of Parliament shared Alec's memories up until the point of his creating them but to make sure things would be set in motion how he remembered them, after the thirteenth elemental Mantago the Parliament stopped sharing their memories with their successors and forced them to create a second circle (a group that would often accuse Alec of being a failure because they were unaware of the greater truths their predecessors witheld from them). So it was that over the years, the Parliament would guide Alec...either through lies or genuine concern, leading to a relationship strained at times but Alec understands how essential and useful the Parliament is while Abby does not always agree.
The Parliament first appeared in Swamp Thing #47 (April 1986) and was created by Alan Moore, Stan Woch and Ron Randall, although many later creators would create key members and give it a much larger history than Moore did.