MCU Theory: How Groot Has Reached 'King Groot' Form When The Original Groot Did Not

With Guardians Of The Galaxy Vol.3 arriving to purchase on digital platforms (while, impressively, still running a few sessions a day in most theatres), fans are eagerly revisiting the film. The movie's first credits scene sees the introduction of the group who will likely be the MCU's new primary Guardians team going forward, consisting of Rocket Raccoon, Kraglin obfonteri, Phyla-Vell, Adam Warlock, Cosmo the Spacedog, and Groot, who emerges from a nap in a new, large, powerful form.

Fans have dubbed this form 'King Groot', inspired by a similar looking alternate incarnation of Groot from the comics. While mostly pleased by the new design, some fans were confused as to how Groot has reached the King Groot stage at a relatively young age, when his Father, the original Groot, who was presumably older than his so's current age at the time of his death, did not.

A new theory offers a possible explanation, based around a unique ability of Groot's race.

A little bit of Photosynthesis

Groot, both the original and his son, are members of the Flora colossi, a race of sentient and highly intelligent trees hailing from Planet X. In the comics, the Arbor Masters, ancient, wise Flora colossi that rule over the Planet, transfer the knowledge of their race's history to young Saplings through the process of photosynthesis. This process also allows the Flora colossi to share energy amongst themselves, helping the younger ones with their growth.

The current Groot, who has been raised from birth by the Guardians and never been to Planet X, has missed out on receiving the wisdom of the Arbor Masters as his Father most likely did. However, photosynthesis is a natural physical process for plants, so from an energy standpoint, Groot, without knowing it, has probably picked up energy from a few sources that have given him an advantage over the original Groot regarding the rate of his growth.

For example..

Peter Quill, aka Star-Lord

While Rocket Raccoon is the primary caretaker of Baby Groot in Guardians of the Galaxy Vol.2, he still spends a lot of time around the other Guardians, including Peter Quill, also known as Star-Lord. In Vol.2, it is revealed that Quill is half-Celestial through his Father, Ego. Aside from providing an explanation for how Quill was able to survive direct contact with the Power Stone in the first Guardians of the Galaxy, his Celestial heritage also made him effectively immortal, and gave him the ability to connect with and control the energy of Ego's planet.

We can assume that Baby Groot absorbed some of this energy. While Quill loses his immortality and Celestial power following Ego's death, Groot had probably already got some benefit out of it.

Ego/Anulax batteries

When the Guardians discover Ego's plan to expand his power across the universe, already having killed and drained hundreds of his own children in the process, they know they must stop him. The only way to do this is to destroy Ego's brain, which lies at the core of the planet. Rocket builds a bomb from the Anulax batteries he stole at the beginning of Vol.2, and, reluctantly, sends Groot into Ego's core to plant the bomb, as he is the only one who could fit.

Being so close to Ego's centre of power, it is quite possible that Groot absorbed pure Celestial energy during this sequence, which may have advanced his growth. While it's not clear whether or not the photosynthesis ability extends to inanimate objects, if it does, he could also have absorbed energy from the batteries, in Rocket's possession, and therefore within Groot's reach, for the majority of the film.

Stormbreaker

By the time of Avengers: Infinity War, Groot has grown into a moody, surly teenager, with his behaviour throughout the film reflecting this difficult life stage. However, after a trip to Nidavellir to get Thor a new weapon goes awry when the great forge fails to produce Stormbreaker's handle, Groot awakens his inner hero, sacrificing one of his own arms (don't worry, it grows back) to become a handle for the axe.

Again, the extent of Groot's abilities when it comes to inanimate objects is unclear, but Asgardian weapons, at least those belonging to Thor, have been shown to posess some degree of sentience, so it is possible that Groot absorbed energy from Stormbreaker during the time he was attached to it. Some fans even speculate that Groot may still have a distant symbiotic connection to the axe due to the part of himself used in it's creation.

Thor

Throughout Avengers: Infinity War, and the window of time between Avengers: Endgame and Thor: Love and Thunder, Groot spends a significant amount of time in the company of Thor. As an Asgardian Prince and the God of Thunder, Thor is inarguably one of the most powerful Avengers.

Spending time with, and sharing the energy of, a literal God, was clearly advantageous to Groot's growth, and one of the main factors to which fans have attributed his achievement of 'King' form, considered God-like by other Flora colossi in the comics.

Tony Stark's snap

Groot, along with all the MCU's other heroes, was present when Tony Stark performed his brave sacrificial snap to eliminate Thanos and his army and save the universe. Like any use of all six Infinity Stones, the snap resulted in a large expulsion of energy across the battlefield.

Groot may have absorbed some of this energy as well, further aiding his growth.

Adam Warlock

Adam Warlock, considered in the films to be a God-like figure of the Sovereign race, is briefly teased during the credits of Guardians of the Galaxy Vol.2, before making his first full MCU appearance in Vol.3. He spends most of the film as a somewhat reluctant antagonist, tasked with retrieving Rocket Raccoon to the High Evolutionary.

Towards the end of the film, Groot rescues a badly injured Adam from the High Evolutionary's crumbling ship, as he believes everyone deserves a second chance. Adam subsequently returns this kindness by saving Peter Quill from death. He is then shown as a member of the new incarnation of the Guardians in the film's mid-credits scene.

In the comics, Adam Warlock is one of the most powerful figures in the Marvel Universe, and this will likely also be true in the MCU as he continues to develop. Groot's new teammate likely gave him the last spark of energy he needed to attain 'King Groot' size.

Bring on more King Groot!