DoctorC' Planet: Veilsel
Population: Plantae descendents
Veilsel is often called "The Reservation Capital" in Serenity. The entire planet is an exotic reserve for flora and fauna from all around The Interstellar Union. Originally, there was supposed to be only a couple of research/maintenance crews, however, few enthusiastic researchers, led by brilliant prof. Johanna Mitchel developed a stimulant, causing temporary boost in plant's evolutionary process. Result was dozen members of a new species - Plantae descendents, trees and flowers, evolved to the point of sentience. Now, alongside the research teams sent by Serenity, thousands of these evolved plants live in fourteen different maintenance stations, located on Veilsel. The community's mostly dedicated to maintain the Veilsel as one of the top tier reserve planets in Serenity's store, or to train newly graduated biologists. Aside from that, Plantae descendents and Serenity's ecologists offer a hospitable stay to anyone looking for a stroll through the Reservation Capital.
TribalTrouble's Planet: Terra
Population: Humans
Terra was one of the planets Serenity is most known for: By the time the ICO reached Terra, or "Earth", as some of the natives call it, the planet was in terrible condition, losing over 83% of all life forms, including almost entirety of sentient population. The few thousand people and a lot of other barely surviving lifeforms left on the planet were transported to several reserve spots in order to preserve the receding flora and fauna of the dying planet. Eventually, Terra was cleared out by Serenity and most of the residents were transported back home, leaving out just a few dozens members of each species on their reserve planets. Nowadays, humanity is thriving under their sun once again. They do take a much more careful approach with how they treat the reformed Earth, however, and with the help of Serenity will hopefully reach their former glory once more. One thing's for certain - humans do take great pleasure in working with Serenity to find better ways to live and learn new things.
Muffin's Planet: Xvatri
Population: Sidri'leni
Xvatri is populated by a lot of different species from all across the Interstellar Union. Main role of the Xvatri is a giant planet-market, so, naturally, many different enthusiasts would come there to trade and make some money. As busy as it gets, Xvatri people don't tend to care about trivial stuff, like relationships or families - they're there for the profit and only profit. The majority, at least. There is, however, a race native to Xvatri, called Sidri'leni, from which MrMuffin came to Serenity. Most of Sidri'leni were pushed away by the marketers and traders, almost forced to leave until Serenity's Parliament declared that Sidri'leni should have at least 60% of their planet back. Xvatri was handed back to Sidri'leni, though part of it is still used by busy traders.