If at first you kind of succeed, try try again. Or it would seem, as Vin Diesel appears to be trying to gin up interest among his legions of fans for a ?Guardians of the Galaxy? spinoff film focused on his character, the sentient plant named Groot. Speaking to MTV News UK while promoting his latest film ?xXx: The Return Of Xander Cage,? Diesel said a stand-alone Groot pic has already been considered by ?Guardians of the Galaxy? director James Gunn.