Groot is the tree-like being seen as a member of the Guardians of the Galaxy and, later on, an Avenger ally. The lovable creature is an alien being from Planet X and belongs to the species of Flora Colossus. The Flora Colossi have high intelligence but constricted vocal cords, making their communication difficult for other species to understand.
The wooded hero has been a great warrior, fighting mega villains like Thanos along with the Guardians and the Avengers. While he has the power to regenerate and grow into a new being every time he dies, he cannot reproduce a population of Flora people to have more of his race. So yes, he is the lone surviving Flora being in MCU.
The rebirth of the character in movies shows that he can always be resurrected, though as a new individual. While enjoying superior regenerative powers, Groot seems to be the only one left from his species in the Marvel canon because his home planet has been destroyed.
Exploring Groot’s origin and separation from his planet
Groot is a Flora Colossus from his home world, Planet X, ruled by the Arbor Masters. The Arbor Masters passed on “Photonic knowledge” to their children through photosynthesis.
This special education was the compilation of all the knowledge of the previous generations which made the Flora Colossi brilliant. Groot’s special “sap line” made him smarter than most other Flora beings.
The biome of Planet X was kept in balance by creatures called “maintenance mammals”. The woody warrior was comfortable with and sympathetic towards these captive beings.
When some of the Flora people abducted a young girl named Hannah from Earth, the compassionate hero realized the wrong done and helped free Hannah. As a punishment, he was exiled from his home planet.
According to Guardians of the Galaxy #14, Groot was exiled because he defended one of the maintenance mammals from another sapling and in the course of action, killed the sapling.
Wandering in the universe, the wooded superhero met Rocket Raccoon and soon they joined Star-lord to form the Guardians of the Galaxy. His exile may have kept Groot alive while his species perished. He also has the power to regenerate and be reborn.
What happened to the Flora Colossi of Planet X?
While there are some parallel stories on how the Flora Colossi were destroyed, the most commonly accepted version says that the planet was invaded by Ronan the Accuser who wiped out the species completely. While the woody warrior survived the mass extinction, he also managed to save the “world pod” inside him. He only needed to plant it in a sacred pool to revive his race.
A battle with Thanos had rendered the world pod useless. However, Adam Warlock restored it and the hero wanted to resurrect Flora Colossi people by planting it on Planet X.
With the help of The Guardians of the Galaxy, the tree-hero took the world pod to his home world to plant it. However, Thanos had infested the planet with savage symbiotes. To get rid of the infestation, the Guardians had to destroy the planet.
The Guardians, including the wooded hero, then traveled to Planet Y, which has pure symbiotes, and planted the world pod. The new Flora Colossi will sprout and coexist with the symbiotes in a billion millennia, as per this storyline which occurs in the Marvel universe of Earth-17628.
In another version of Earth-TRN912, Planet X was attacked by the Chitauri during galactic war and the Chitauri are responsible for the extinction of the Flora Colossi.
Final words on the only surviving Flora Colossus in the universe
As an extension of the MCU, the main Marvel canon believes that the Flora world is destroyed and the wooded warrior escaped narrowly. That leaves the bark-covered hero as the survivor Flora Colossus. As such, MCU has always implied that he is the last one.
Within MCU, when he died during a battle, his friend Rocket Raccoon managed to plant a twig from his dead body. This led to the birth of Groot II, who moviegoers and fans have loved to watch grow up and was last seen in the recently released Guardians of the Galaxy Vol.3. He may continue his adventures with his extended family, The Guardians, for some time now.