Well, water normally passes from root hair cells to cortex to endodermis, and from there to the xylem vessels. All of this occurs down the water potential gradient by apoplastic or symplastic pathway through these cells. I was wondering how water potential differs in each of these cells for water to be transported. BTW I'm confused why my teacher said that the water potential in xylem vessels(the tracheids) is highest among all the cells I mentioned. Then how come water can move down the water potential gradient?