Root+Tissues+Note

=Types of Tissues in Roots=

(Chapter 16.1, pg. 532)

Outside. **Epidermis**
 * one cell thin layer on the outside of roots
 * root hairs on epidermal cells (1) increase surface area and (2) absorb water and minerals

Middle. **Cortex**
 * layer of cells just below epidermis
 * rather thick layer
 * water passes through cells to vascular cylinder by osmosis

Middle. **Endodermis**
 * layer of cells at centre of cortex, but surrounding vascular cylinder
 * **Casperian strip** is a wax coating around the endodermis
 * makes water go through endodermis by osmosis with help of minerals
 * minerals are pumped through endodermis by active transport (uses energy)
 * higher concentration of minerals in vascular cylinder “suck” water into root by osmosis

Inside. **Vascular cylinder**
 * contains xylem and phloem
 * the high water pressure built up in the vascular cylinder by osmosis forces water from roots up into the stem
 * this pressure is called **root pressure**