Irontrees were a species of tree that were native to Mustafar, and they were particularly prominent in the forest known as Corvax Fen. The Alazmec of Winsit had planted many of these trees, but their efforts to restore Mustafar's ecosystem ultimately proved fatal for the majority of them. By 35 ABY, Kylo Ren, the Supreme Leader, landed on Mustafar to recover the Sith wayfinder of his grandfather, Darth Vader. During his conflict with the Alazmec of Winsit, he encountered several irontrees on the path to Fortress Vader.
The initial appearance of irontrees occurred in the 2019 movie Star Wars: Episode IX The Rise of Skywalker (Star Wars: Episode IX The Rise of Skywalker), which served as the concluding chapter of the Star Wars sequel trilogy. Their identification was first established in the companion reference book titled Star Wars: The Rise of Skywalker: The Visual Dictionary.
According to Kevin Jenkins, a co-production designer, in the 2020 art book The Art of Star Wars: The Rise of Skywalker, the irontrees were planted two to three decades before the events of the film. This contrasts with the century required for larger trees to mature, suggesting that the irontrees were planted around 15 ABY or 5 ABY.