A long time ago, a cosmic event created a single drop of sunlight, which fell "from the heavens" and grew the golden flower. It had the ability to heal any sickness or injuries, even mortal wounds, as demonstrated by Rapunzel, delay aging, as demonstrated by Gothel, though that ability requires constant use of the power.
One day, Mother Gothel discovered the flower, and chose to hoard its healing power for herself. She used it to keep herself young for hundreds of years, and all she had to do was sing a special song. It appears that when the song is sung, the flower releases pollen which is breathed in. Even though Mother Gothel had hidden the flower, other people knew of its existence, suggesting that this flower was not the first of its kind.
The golden flower has been considered to be the most powerful object in "the Seven Kingdoms" according to Corona's history. In the years after the flower was picked, the spot where the flower grows became a sacred and forbidden site, with a small pedestal in its place and large, indestructible thorn-like rocks surrounding it. Like the flower before them, these rocks have magical properties, as demonstrated when Rapunzel touches one of them and resulted in her previously long, magical golden locks to regrow, and in this case inheriting the rocks' indestructibility. According to the research of Lord Demanitus, the cosmic event that created the Sundrop also created a single drop of moonlight, which took the form of an opal. From this opal were the black rocks created.
Centuries after the flower bloomed, a kingdom across a lake from where the flower grew came into being. The kingdom was ruled by a benevolent King and Queen. The queen was about to have a baby, but fell seriously ill. Knowing that she and her unborn child would surely die if a cure was not found soon, the entire kingdom went searching for the flower.
When Gothel left the flower in plain sight by accident, one of the kingdom's soldiers found the flower, and it was uprooted and brought back to the castle, where it was made into an infusion for the queen. Afterwards the queen recovered, and gave birth to a healthy baby girl: Princess Rapunzel who was born with the rest of the flower's ability. Rapunzel gave a drop to Eugene to heal his stab wound that he received from Gothel, but still has most of the flower within. Perhaps as a thanks to the flower for saving the queen and Rapunzel, at the cost of its own existence, Corona adopted the sun as its symbol.
In "The Alchemist Returns", it is revealed that the flower still existed but was faded, and it had been kept locked away in Corona Castle's heavily-guarded vault, by orders of King Frederic. Varian, an alchemist looking to use the flower's legendary properties for his own agenda, manipulated Rapunzel into breaking into the flower's chamber. After stealing it, he used one of the flower's petals for an experiment, and discovered that its magic had long dissipated and transferred to Rapunzel. In anger, he crushed what remained of the flower into powder.
In "Secret of the Sun Drop", after Varian abducts Queen Arianna, King Frederic confesses to Rapunzel that on the night of her birth, he was warned by Quirin that removing the flower from its resting place would reap unimaginable consequences and awaken a darkness, resulting in the growth of the Black Rocks.
In "Lost and Found", Lord Demanitus, whose spirit was inhabiting the body of Vigor the Visionary, reveals to Rapunzel and Eugene that the Sundrop is one half of an ancient power seeking to reunite with its other half, the Moonstone Opal.
In "Cassandra's Revenge", Varian discovered a hidden fourth incantation on the Graphtic Scroll, enabling Rapunzel to unlock the Sundrop's full power, which she used against the Moonstone-wielding Cassandra. The clash of energies from two opposing cosmic forces inadvertently allowed Zhan Tiri to escape her otherworldly prison.
In "Plus Est En Vous", as an eclipse loomed over Corona, the Sundrop's power coalesced into a golden jewel much like the Moonstone, while at the same time, caused its power to weaken. By the time the eclipse was in its prime, Cassandra managed to separate Rapunzel from the Sundrop causing her hair to revert to brown. Subsequently, Zhan Tiri betrayed Cassandra and took both elements for herself, transforming into her true demonic form with the intent to destroying Corona. However, Cassandra passed Rapunzel the shard of the Moonstone, temporarily restoring her golden hair and they both fought against Zhan Tiri. Using Rapunzel's hair, they united the Sundrop and Moonstone, restoring the Ultimate Power and destroying Zhan Tiri in the process. Rapunzel then used the Ultimate Power to heal an unconscious Cassandra as well as all Corona citizens affected by the Decay Incantation before releasing it into the cosmos.
The Sun Drop Flower is featured as part of the Wicked Nine, a collection of objects which have the potential to unleash unspeakable power if brought together.
The flower first appears in the episode "Eloise Gardener". When Gothel is trapped by the tower's blood magic concealment, she disguises herself as Rapunzel, and tasks the Wish Realm's version of Hook to retrieve it for her. When he successfully obtains it, she seduces him, and the pair have sex. Gothel's encounter leaves her pregnant, and she uses the flower's magic, to accelerate her pregnancy overnight, so she can leave her baby, in her place, as a prisoner of the tower. Gothel used a powdered form of the flower to originally entrap Rapunzel in the tower, as shown in "One Little Tear". The flower is mentioned, in "Sisterhood", when Gothel tasks Drizella in retrieving it, to join her coven.
- In the original fairy tale, Rapunzel's mother did not ingest a golden flower, but a rampion plant (Campanula rapunculus), a species of bellflower and a root vegetable similar to parsnip. The rampion had no mystical properties nor ties to Rapunzel's birth, but Rapunzel was named after it.
- The shape of the golden flower seems to be based on the flower of rampion.
- Both the Campanula rapunculus and the Valerianella locusta are known as rapunzel.
- In Moana, the flower briefly appears near the epilogue, when the camera zooms into Tui and Sina inspecting the island's recovering flora.
- It is implied that prolonged exposure to the flower (and later Rapunzel's hair's) magic can cause the user's body to become dependent on its magic to survive, as Mother Gothel, who has used the flower's magic both directly and through Rapunzel's hair constantly for decades, turned to ashes when Rapunzel's hair was cut and its magic destroyed, while Flynn Rider and Pascal, both of whom were only exposed once to its magic through Rapunzel's hair, were unaffected by it.
- In Kingdom Hearts III, the Sundrop Flower does not make an appearance nor was it addressed in the world "Kingdom of Corona", but appears as part of the handle for the "Ever After" keyblade. The flower does, however, also appear on a fabric when Rapunzel figures out she is the lost princess, just like in the movie.