Principal pathways for translocation of materials after uptake by the roots of leaves of a plant

1. Movement in the xylem along the transpiration stream. It allows the upward movement of organic materials in the xylem from the soil solution into foliage.
2. Through the phloem or other cells such as ray parenchyma. This is the major pathway of movement of materials applied to the leaves. Subsequently, phloem flow may take solutes up to the stem apex as easily as down to the lower parts of the plant.
3. Through the cell walls. Aqueous network through the cell walls is described as apoplast (outside protoplast). It is the principal region of the apparent free space.
4. Through the intercellular spaces. The rapid systemic permeation of gases and volatiles through the plants indicates a ready movement through the intercellular spaces.