The Symplast pathway is one of the paths which water takes to move through the
cells of a
plant. It is a system of interconnected
protoplasts in the plant. Some water is lost to the
sub-stomatal air space from the
cytoplasm of cells surrounding it. The
water potential of this cytoplasm is therefore made more negative (lower). Between adjacent cells are
plasmodesmata - tiny
pores in the
cell wall between plant cells through which a living strand of cytoplasm runs between two cells which links the cytoplasm of one cell to the cells around it.
Water may pass along these plasmodesmata from adjacent cells with a less negative (higher) water potential. This loss of water makes the
water potential of the second cell more negative (lower), which may in turn replace the water with water from cells with a less negative (higher) water potential.
In this way, a steady concentration
gradient is set up between the
sub-stomatal space and the
xylem vessels of the leaf, through the cytoplasm. This is not the same method as the
apoplast pathway or the less important
vacuolar pathway use.