What part of the flower has the primary function of protection?

The sepal is the part of the flower that serves the primary function of protection. It is typically found at the base of the flower, encasing and safeguarding the developing bud before it opens. In many species, sepals can also help protect the flower from environmental factors and potential herbivores.

While the petals, stamen, and pistil play vital roles in reproduction and attraction (with petals primarily attracting pollinators, stamens producing pollen, and the pistil being involved in ovule production), none of these structures are primarily built for protection in the same way the sepals are. The sepal's protective function is crucial during the early stages of flower development, ensuring the reproductive structures are shielded until they are ready for pollination.