Irontrees were a species of tree that were native to Mustafar, most notably located in the forest known as Corvax Fen. The Alazmec of Winsit had planted many of these trees in a futile effort to restore Mustafar's environment. Due to the planet's severe environment, the majority of the trees died. A few irontrees were being transported to Fortress Vader by 35 ABY, when Supreme Leader Kylo Ren traveled to Mustafar to retrieve the Sith wayfinder that once belonged to his grandfather, Darth Vader, as he battled the Alazmec of Winsit.
The 2019 film Star Wars: Episode IX The Rise of Skywalker, which served as the final chapter in the Star Wars sequel trilogy, marked the initial appearance of irontrees. Their identification occurred in the reference book Star Wars: The Rise of Skywalker: The Visual Dictionary that accompanied the film.
Kevin Jenkins, the co-production designer, revealed in the 2020 art book The Art of Star Wars: The Rise of Skywalker that the irontrees were planted between twenty and thirty years prior, compared to the century required for larger trees to mature, indicating that their plantation took place around 15 ABY or 5 ABY.