1. Roots anchor the plant and keep it upright
absorb water and nutrients from the soil
may store water and carbohydrates

2. Types of Root Systems taproot system
has a large, thick, main root called a taproot, which grows straight downward
push deep into the soil
gymnosperms and angiosperm eudicots have taproot systems

3. Types of Root Systems Cont’d…
fibrous root system
has many small roots
tend to be shallower than taproots
occur in angiosperm monocots
Both root systems have root hairs and can have lateral branching

4. Structure of Roots
the tip of the root contains the root cap and a meristem
root cap is a thick layer of cells that produce a slippery substance that helps the root to penetrate the soil, minimizing damage to the root cells
meristem produces new cells to increase the length of the root
Monocots do not produce wood, but some have tissues that have a similar function, such as the stems of some palms and bamboos

5. Structure of Roots Cont’d…
root hairs above the root tip project out of the epidermis and increase the surface area for absorption
root cortex is a region of parenchyma cells beneath the epidermis that stores carbohydrates and helps transport water from the epidermis to the xylem
walls of the cells in the endodermis are wrapped with a wax-like substance, forming a continuous barrier called the Casparian strip

6. Structure of Roots Cont’d…
vascular cylinder contains the vascular tissue of roots
in gymnosperms and eudicots, the centre of the root contains xylem cells forming an “X” or star-shape in the centre of the vascular cylinder
the phloem cells are also in the centre of the root, around the xylem
arrangement of xylem and phloem within the vascular cylinder varies among the groups of angiosperms

7. Structure of Roots Cont’d…
in monocots the centre of the root contains parenchyma cells surrounded by a ring of xylem cells and a ring of phloem cells

8. Homework
Answer 12.4 questions #7, 9 & 10 on page 563