Stem, in botany, the plant axis that bears buds and shoots with leaves and, at its basal end, roots. The stem is the stalk of a plant or the main trunk of a tree. The stem conducts water, minerals, and food to other parts of the plant; it may also store food, and green stems themselves produce food. In most plants the stem is the major vertical shoot, in some it is inconspicuous, and in others it is modified and resembles other plant parts (e.g., underground stems may look like roots).