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How does a seedling use stored food before it can photosynthesize?

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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.

Before a seedling becomes nutritionally self-supporting through photosynthesis, it relies on food reserves provided by the parent sporophyte. These reserves are typically stored in the endosperm, the cotyledons, or other residual tissues of the ovule.123

Because these stored materials—such as starch, proteins, and lipids—are often in insoluble forms, the seedling must first mobilize them. The embryo secretes enzymes to digest these reserves, converting them into soluble products that can be translocated to active areas of growth.123

In many plants, the cotyledons play a critical role in this process:
* Absorption: In some species, cotyledons act as absorbing organs that withdraw nutrients from the endosperm. For example, in grasses, the cotyledon is modified into an enzyme-secreting scutellum that facilitates this transfer.435
* Storage and Conversion: When reserves are stored directly within the cotyledons, the nutrients are transferred to the developing radicle and shoot. Afterward, these cotyledons may wither or develop chlorophyll to begin photosynthesis themselves.13