Casparian strips are chemically made of
The tangential walls and radial walls of endodermal cells have thickenings named as Casparian thickenings made of hydrophobic substance called Suberin. Due to this, endodermal cell wall is impermeable to mineral water and all the water collected mainly in the intercellular region of cortex has to take symplastic path from endodermis on wards for getting it dumped into the xylem.