The structure marked with an X in the figure below is called a stored nutrient reserve.
The seeds are basically formed by an integument (outer part, a stored reserve and the embryo (it is in the center of the seed), the embryo is the main creator of a new plant, for that, it needs a high load of nutrients that is provided by the nutrient reserve. In addition, the stored nutrient reserve protects the embryo from external factors such as solar radiation and freezing.
The party of the leaf are the xylem and the Pholem they help transport water to the leaves.first the water is sucked up throughout the roots then travels up the xylem and pholem and then the water is transported to the leaves