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What role does the endosperm play in a developing seedling?

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Cluster of bright red seeds emerging from the cone-shaped fruit of a magnolia grandiflora, surrounded by large, glossy green leaves. — seed Fruit and seeds of the southern magnolia (*Magnolia grandiflora*). The fruit is an aggregate of follicles, and each follicle bears a single red seed.

The primary role of the endosperm in a developing seedling is to serve as a vital nutrient-storage tissue that nourishes the embryo during its early stages of growth and germination.12

Formed through the process of double fertilization, this tissue contains essential reserves such as starch, sugars, fats, proteins, and [hemicelluloses]. The way these nutrients are utilized varies by plant species:23

Direct Absorption: In many plants, such as wheat, the endosperm remains present until germination, at which point the cotyledons (seed leaves) act as absorptive organs to mobilize and transfer these stored nutrients to the growing seedling.13
Early Consumption: In some species, such as peas and beans, the endosperm is completely absorbed by the embryo before the seed reaches maturity. In these cases, the nutrients are stored directly within the fleshy cotyledons, which then nourish the embryo during germination.12
Specialized Structures: In grasses, the cotyledon is modified into a structure called the scutellum, which secretes enzymes to break down and absorb nutrients from the endosperm.3