Groot is a fictional character and member of the Guardians of the Galaxy, published by Marvel Comics.
When Herbert explodes upon finding out that Peter is really Chris' dad in "Con Heiress", his dog Jesse gathers up the pieces and plants them, allowing Herbert to regrow in the same manner as Groot.
Peter carves a likeness of Groot into a tree stump with a chainsaw in "Boys & Squirrels", while the rest of the guys have issues with Joe's pronunciation of things, including 'Marvel.'