The Haluu were a race of sentient plants.
When one of their kind, Sythorr, was in favour of overgrowing worlds, eating "fleshlings", and waging war, others believed it was wrong, and Sythorr left his race in a domed escape pod containing a Garden. He created his own Haluu followers by filling his Garden with human "souls". The escape pod hid on Titan for centuries until a ship arrived, but Sythorr's love Oksanna sacrificed herself to destroy the Garden along with Sythorr to atone for her actions. (COMIC: The Soul Garden)