Reddit user Independent-Design17 proposed a fascinating connection between Elden Ring's Erdtree and the Australian Christmas tree, Nuytsia floribunda. Superficial similarities are evident, particularly when comparing the in-game Small Erdtrees to Nuytsia. However, the parallels run deeper.
Elden Ring lore depicts the Erdtree as a guiding force for the souls of the deceased, reflected by the catacombs at its base. Intriguingly, Nuytsia holds similar spiritual significance in Aboriginal Australian culture, its flowering branches representing the souls of the departed, their vibrant color echoing the sunset – the perceived destination of spirits.

Further strengthening this connection is Nuytsia's semi-parasitic nature; it draws nutrients from neighboring plants. This resonates with fan theories suggesting the Erdtree is parasitic, having potentially usurped the life force of an ancient Great Tree. However, it's now understood that game descriptions referencing a "Great Tree" were mistranslations, actually referring to the Erdtree's own extensive root system.
Ultimately, whether FromSoftware intentionally drew inspiration from Nuytsia floribunda remains a mystery known only to the developers.