For water to move from the soil through the plant and into the air, which order of water potentials must hold?

1. Water always moves down a water potential gradient, from higher to lower. 2. The path from soil to air runs soil, then root, then stem, then leaf, then atmosphere. 3. So each step must have a lower water potential than the one before it for transpiration to proceed. 4. That gives soil greater than root, root greater than stem, stem greater than leaf, and leaf greater than atmosphere. 5. Reversing the inequality would drive water from the air back into the soil, which is not what a transpiring plant does. 6. Shuffling leaf and root in the middle breaks the physical route the water actually takes through the plant body. _Source: OpenStax Biology (1st ed., CC BY 4.0), Ch 30 "Plant Form and Physiology", section 30.5 Transport of Water and Solutes in Plants_