In general, lilies symbolize innocence and purity, but there are several types of lilies used on gravestones and they have slightly different meanings.
The image of calla lilies on a tombstone symbolizes majestic beauty, marriage, and fidelity.
The South African calla lily, with its beautiful vase-like blooms, was introduced in the U.S in the late 1800s. It wasn’t long after this that these flowers became popular funeral flowers and their images appeared as cemetery art.