Vascular tissues transport water, minerals, and food throughout plants. Xylem tissue transports water and minerals from roots to stems and leaves through hollow, nonliving cells. Phloem tissue transports manufactured food like sucrose from leaves to other plant parts through sieve tubes and companion cells. Mineral salts enter root hairs through diffusion while water enters through osmosis, then both are transported through the xylem to the rest of the plant.
Transport of sugars and dissolved solutes in the phloem is kind of like water movement in the xylem in reverse. Sugars are actively pumped into the phloem sieve tube cells in the leaf. Thus the solute potential increases, making the water potential of the sieve tube cell more negative and water is drawn in from surrounding cells. In the root (and other tissues actively abstracting sugars), sugars are removed, lowering the water potential. This difference in water potential between the leaves which are actively uploading sugars, and the roots and other tissues actively removing them drives a bulk flow of water in the phloem with the sugars and other dissolved solutes. In the leaves, the concentration of sucrose in the sieve tube cells can reach as much a 1molar. This is equivalent to 10 atmospheres of pressure which can drive a bulk flow of water and sugars through the sieve tubes.
![Vascular tissues ,[object Object],[object Object],Copyright © 2010 All Rights Reserved](https://image.slidesharecdn.com/2xylemphloemtransportwatermineralsalts-101019024252-phpapp01/85/Chapter-9-Transport-in-Plants-Lesson-2-Xylem-and-Phloem-structure-and-function-1-320.jpg)
