The Flower of Rebirth is a plant whose seeds rebirthed the Yonder Galaxy after it were destroyed by Lord Dominator.
Wander and Sylvia were on one of a series of planets destroyed by Lord Dominator, Sylvia stating that there was no hope for the galaxy. As she waited for Wander to comfort her, she saw that Wander him self was distraught. Despite her best efforts to lift his spirits, Wander saw no reason to turn his spirits around.
Sylvia then pointed out a single flower, which seemingly placed a smile on Wander's face, only for the flower to begin to wilt. Sylvia then pointed out that they would save the flower no matter what happened. They tried finding the perfect planet, but each planet was either too hot, too cold, too wet, or had quicksand and/or giant bees. Wander started to worry even more, but then they realized they were on the perfect planet.
All of a sudden, Dominator came to the planet and took the flower, and it was already in poor shape. When Wander and Sylvia appeared to be sad, Dominator took a selfie with them and texted it to an unknown recipient. However, she appeared to be allergic to the flower, as she began to sneeze uncontrollably.
As the two were leaving the planet, Wander showed Sylvia the dead flower. Sylvia went into a panic and performed CPR acts on the flower after landing on another planet. She took a quick glance at a tearful Wander, and a tear begins to fall towards the ground. Sylvia tried catching it, but when it hited the planet's surface, she also began to cry. Wander pointed out that it was okay to be sad, but Sylvia explained that there won't be any hope if Wander was sad. Wander replied with the fact that just because he was sad didn't mean he had lost hope. By that moment, both of them were in tears as the flower disappeared into open space. The flower had turned into seeds, which spreaded across the galaxy and grew more flowers.