Symplast Apoplast and Vacuolar Pathway

To drink water from the soil, plants have a natural straw, their roots that have tiny root hair to take in water. Let's see a Magnified version of the root hair.

The outermost cell of the root is called the epidermis. Root cell contains a cell wall, a cell membrane, a vacuole, a nucleus, and the straw type root hair. Each cell is connected to the other cell through a door called plasmodesmata. In vacuolar Pathway the water molecules moves through the Plasmodesmata door and the vacuoles to travel from one cell to another. It moves from epidermis, cortex, endodermis, pericycle, xylem, and reaches the stem and leaves of the plants.
Although it may seem to be a straight route, the water molecules face high resistance during this transport, due to which this pathway is hardly used.

Another way of transport is through the symplast pathway, wherein the water molecules move by osmosis using the plasmodesmata door and the cytoplasm for movement from one cell to the other to reach the xylem and travel to the stem and leaves
In the apoplast pathway, water molecules move through the cell wall and cross the epidermis and cortex. However, it cannot cross the endodermis due to the Casparian Strip which is impermeable to water due to the presence of a waxy water-impermeable molecule , Suberin. This helps in the development of root pressure.


Since the apoplast pathway cannot proceed further, the water molecules are pushed in the cytoplasm and continue with the symplast pathway, it travels from the pericycle to xylem. In the xylem, the apoplast pathway continues and the water molecules reach to the stem and leaves of the plant.