What does the stem transport from the roots to the rest of the plant?

Stem, in botany, is the plant axis that bears buds and shoots with leaves and, at its basal end, roots. The stem conducts water, minerals, and food to other parts of the plant; it may also store food, and green stems themselves produce food. The primary functions of the stem are to support the leaves, to conduct water and minerals to the leaves, where they can be converted into usable products by photosynthesis, and to transport these products from the leaves to other parts of the plant, including the roots.

Source: Encyclopædia Britannica