What is the function of the stigma in the flower's reproductive system?

The stigma plays a crucial role in the reproductive system of a flower, as it is the part of the pistil that receives pollen during the process of fertilization. When pollen grains, which are the male gametes, land on the stigma, they germinate and grow a pollen tube down through the style to reach the ovary. This is where the fertilization of the ovules takes place, leading to the formation of seeds. Therefore, the function of the stigma is directly tied to the flower's ability to reproduce by facilitating the initial step of pollination, which is essential for the continuation of plant species.

Other roles within the flower, such as providing support, producing nectar, or protecting seeds from predators, involve different parts of the flower structure and do not pertain to the specific function of the stigma.