Cotyledon (noun)

1. The first leaf or leaves produced by a plant embryo.
2. A leaf that is a characteristic of the seedling of a higher plant, serving to store food.

Origin:

From the greek word kotyledon, meaning 'cup-shaped', in reference to the shape of the embryonic leaves in plants.

Examples:

1. The cotyledons of a tomato plant are the first leaves to emerge.
2. The young seedling was sustained by the nutrient-rich cotyledons.
3. The size and shape of the cotyledons can vary greatly depending on the species of plant.
4. The botanist studied the development of the cotyledons in various plants.
5. The mature plant grew from the cotyledons, which eventually withered away.