Here's why:
* No Complete Collection: There isn't a definitive, complete collection of all her poems. Some of her work might exist only in private collections or unpublished manuscripts.
* Diverse Output: Mackellar wrote poetry throughout her life, and it was published in various journals, magazines, and anthologies.
* Uncertain Attribution: Some poems may be attributed to her that were actually written by others, or vice versa.
While we don't have an exact number, we can say that she wrote a significant amount of poetry, showcasing her love for Australia and her talent as a wordsmith.