There’s a genuine laugh out loud moment in one of Guardians of the Galaxy 2’s (opens in new tab) five post-credit scenes (opens in new tab). If you’ve seen the movie, you’ll know what I’m talking about. It involves a grumpy Groot who looks… different. If you haven’t seen the movie then look away now as spoilers are on the way. But, as it turns out, that Groot isn’t called what you think he’s called.
Have the six people in the world who haven’t seen Guardians 2 gone? Good.
James Gunn has revealed on a Facebook Live Q&A (via ComicBook.com (opens in new tab)) that Groot’s post-credits scene (opens in new tab) isn’t the Guardian as a teen (treen?) but slightly younger, as the director says about a few viewer faux pas: “Another minor misconception is that people think that's Teen Groot at the end of the movie. And I understand why. It's actually Adolescent Groot. I would call him Tween Groot. Or, we call him 'Adolescent Groot.' He's not quite a teenager yet."
So, there you have it. Groot may be grumpy and physically incapable of tidying his room but he’s not a teenager just yet, he’s Adolescent Groot.
Thinking logically (as I typically do when theorising about fictional tree characters’ ages), it’s probably to account for either a proper Teen Groot in Avengers: Infinity War (opens in new tab) or back to OG Groot from the first Guardians of the Galaxy (opens in new tab). Failing that, we could always get Mid-Life Crisis Groot, complete with Hawaiian shirt.