What does tree symbolise in casuarina tree

The poem "Our Casuarina Tree" is from Dutt's Ancient Ballads and Legends of Hindustan (1882). It is one of Dutt's most famous poems, and it describes a tree near the speaker's home that she associates heavily with memories of her childhood and her siblings that have since died, "Who now in blessed sleep, for aye, repose." The word "our" in the title hints at this significance—it is not just an ordinary tree for the poet, but rather a part of her life and an integral part of her childhood that she shared with her siblings.