Roots

1
Chapter 14

• Roots

2
Primary Functions

• Anchor
• Absorb

3
Secondary Functions

• Storage of Food
• Hormone Production
• Support
• Provide Oxygen
• Transport

4
Root Types
Adventitious roots growing from stems
5
Region of Maturation
Root hair
Region of Elongation
Meristematic Region
Root Cap
6
Monocot/Dicot
7
Epidermis
Vascular Cylinder
Cortex
8
Endodermis
Xylem
Phloem
Pericycle
9
Root Hairs
Epidermis
Cortex
10
Tissue Functions

• Epidermis
• Root hairs
• Cortex
• Root cap
• Root hairs
• Pericycle
• Vascular cylinder
• Endodermis/Casparian strip

• Protection
• Absorption
• Storage
• Protection
• Major absorption
• Origin of lateral roots
• Location of vascular tissues
• Controls passage of minerals

11
Mineral Absorption in Roots

• Active transport into root hairs
• Diffusion through cytoplasm of cortex
• Active transport into the vascular cylinder
• Diffusion up the xylem

12
Primary Growth
13
Secondary Growth
14
Beneficial Associations
15
Mycorrhizas

• Symbiotic relationship
• Fungus obtains some sugars from the plant,
• Plant benefits from the efficient uptake of
  mineral nutrients (or water) by the fungal
  hyphae.

16
Nitrogen Fixing Bacteria

• Symbiotic relationship
• Nitrogen-fixing bacteria in small nodules on the
  roots of legumes, help to return nitrogen to the
  soil
• Bacteria in the nodules use sugars supplied by
  the plant as an energy source.