What are the functions of the endosperm and embryo in a grass seed?

In the seeds of grasses (Poaceae), the endosperm and embryo work in tandem to support the development of the seedling through the following functions:

• Endosperm: This tissue serves as the primary nutrient reservoir for the developing plant. It contains essential storage materials, including starch, sugars, fats, and proteins, which provide the energy and building blocks necessary for germination and early growth before the seedling becomes photosynthetically self-sufficient.123
• Embryo: The embryo contains the rudimentary structures of the future plant, including the root (radicle) and the shoot (plumule). In grasses, the embryo features a specialized structure called the scutellum, which is a modified cotyledon. The scutellum acts as an enzyme-secreting absorbing organ positioned between the embryo and the endosperm; it mobilizes the stored nutrients within the endosperm and transfers them to the growing tissues of the embryo. Additionally, the grass embryo includes protective sheaths, the coleoptile and coleorhiza, which shield the young shoot and radicle during emergence.143