What structure protects the developing seeds of a plant?

The ovary is the structure that protects the developing seeds of a plant. It is a part of the female reproductive system in flowering plants, specifically within the pistil. After fertilization occurs, the ovary develops into a fruit, which encases and protects the seeds as they mature. The wall of the ovary thickens to form a protective layer, ensuring the seeds are shielded from environmental factors and predators.

Other structures mentioned, such as petals, serve different roles — primarily attracting pollinators to aid in fertilization. The stylar tube, which is part of the pistil, connects the stigma to the ovary and facilitates the passage of pollen tubes but does not protect the seeds. The stamen is the male reproductive part of the flower, comprising the anther and filament, and is responsible for producing pollen but does not have a protective function for seeds. Thus, the ovary is uniquely designed for seed protection within the reproductive biology of plants.