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An embryonic leaf; a cotyledon can store a seed food reserve or help transfer it.

A plant organ; a cotyledon is an embryonic leaf.

The young plant inside a seed; its cotyledons and radicle are parts of the plant embryo.

A seed packages a plant embryo, a seed food reserve and a protective seed coat. It is a living starting point for a new plant, not merely stored food. In a mature pea seed, the large cotyledons hold reserves; other seeds retain substantial endosperm. These are alternative arrangements, not successive germination stages.^[ref]

A useful reading exercise is to identify both the future plant and its initial food supply in each drawing. The large yellow area has the same role in both pictures, but it belongs to different plant tissues. Thus location and function alone do not establish tissue identity.

Stored material supporting early seedling growth, located in cotyledons, endosperm or other plant tissues depending on the plant.