What is the primary function of endosperm in plants?

The primary function of endosperm in plants is to serve as an energy reserve for growth. Endosperm is a specialized tissue that forms during the fertilization process and provides essential nutrients to the developing embryo in seeds. It is rich in starches, proteins, and oils, which supply the energy and building blocks necessary for seed germination and the initial growth of the seedling.

As the seed germinates, the endosperm is metabolized to provide the energy needed for the seedling to grow until it can develop its own photosynthetic capabilities and start producing food through photosynthesis. This function is critical for the successful establishment of many plant species, especially during their early life stages when they rely on stored nutrients.

The other options, while relevant to various plant processes, do not accurately describe the primary role of endosperm. Photosynthesis is a function of leaves and stems, water retention pertains more to the external structures of plants such as roots and tissues, and reproduction is primarily handled by flowers and fruits rather than the endosperm itself.