Guardians of the Galaxy #14 reveals the origin of its most tremendous teammate in “Groot’s Tale” by writer Andy Lanning but artist Phil Jimenez.
Groot is a humanoid tree whose sole vocabulary consists of inflections of a single sentence: “I am Groot.” His kind are known as Arbor Masters, who possess a collective consciousness from photosynthesis that allows them to communicate with each other. The monarchs rule over a similarly simple speaking rodent species that make up the working class on Groot’s home planet X, the capital of the Branch Worlds system.
The Arbor children torment the animals but Groot befriends them. The outcast tree snaps when he sees the other children hurting the animals. The usually peaceful Groot becomes so violent that even his little friends appear to be afraid of him. A splash page make the bloodless slaughter of the tree creatures visceral by capturing it inside the blood-red letters “I… AM… GROOT!”
Groot sits among the broken branches of his brethren though they’re not necessarily dead. He has demonstrated the ability to regenerate his entire body from a single twig. His brethren would presumably have the same ability. That doesn’t mean he’s in any less trouble.
The young sapling is reprimanded by a trio of Arbor Masters dressed all in white. These elder Arbors banish Groot for his crimes. He leaves his lush home planet on a cold spaceship by himself though we know he eventually befriends another rodent by the name of Rocket Raccoon, who thankfully is more talkative and serves as translator for the rest of the team.