Reddit user Independent-Design17 proposed a fascinating connection: the Erdtree in Elden Ring might be inspired by the Australian Christmas tree, Nuytsia floribunda.
Superficial similarities are undeniable, particularly when comparing the smaller Erdtrees in the game. However, fans have uncovered deeper resonances. In Elden Ring, the Erdtree guides the souls of the departed, explaining the catacombs at its base. Interestingly, Nuytsia holds similar significance in Australian Aboriginal culture, considered a "spirit tree." Each flowering branch represents a deceased soul, its vibrant hues echoing the sunset – the spirits' final destination, according to their beliefs.
Further bolstering this theory is Nuytsia's semi-parasitic nature. It thrives by drawing nutrients from neighboring plants. This mirrors a popular fan theory about the Erdtree's parasitic nature, suggesting it usurped the life force of an ancient Great Tree. However, it appears that mentions of a "Great Tree" in in-game descriptions are actually mistranslations, referring instead to the Erdtree's own "Great Roots."
Ultimately, only FromSoftware knows if these parallels to Nuytsia were deliberate or coincidental.