Plant Growth

1
Plant Growth

• 26-2
• Unlike animals plants continue to grow and
  increase in size throughout their lives.

2
Guide For Reading

• What are meristems?
• What is a tropism?
• What do auxins do for plant growth?
• What changes must occur as a plant grows?

3
Meristematic Regions

• Apical meristems
• Root meristems
• Cambiums
• vascular cambium
• cork cambium
• Flowers, leaves grow also from meristematic
  tissue.

4
Tropisms

• Plants grow in response to cues from their
  environments.
• These responses are called tropisms.
• (Frame 25668 - LT Side Three)

5
Geotropism

• Reponse to gravity
• Stems grow away (negative)
• Roots grow toward (positive) - (Chapter 18 - LT
  Side Three)

6
Phototropism

• Response to light
• Stems are positively phototropic
• Roots are negatively phototropic

7
Thigmotropism

• Response to touch
• Sensitive plant Briar leguminosae

8
Plant Hormones

• Auxins
• Cytokinins
• Gibbeillins
• Ethylene

9
Auxins

• Produced by the apical meristem
• Apical dominance
• Auxin produces phototropism

10
Auxins

• Apical dominance

Stronger
Weaker
11
Cytokinins

• Like auxins cytokinins effect the rates of plant
  growth and cell division.

12
Gibberillins

• Gibberillins regulate the rate which cells
  elongate.

13
Ethylene

• Ethylene promotes fruit ripening
• (Frame 25296 - LT Side Three)