1. Chapter 5 Secondary Growth
Botany
Chapter 5
Secondary Growth

2. Chapter 5 Objectives (Section 1)
1. Distinguish between primary and secondary growth 2. Describe the arrangement of tissues contributing to secondary growth and the mature tissues derived from each type • Vascular cambium • Cork cambium 3. Relate the growth of the vascular cambium to the formation of wood and bark in woody stems 4. Distinguish between inner bark and outer bark. Identify tissues associated with each.

3. Primary vs. Secondary Growth
Primary growth is elongation
Tissues for primary growth are derived from apical meristem
Apical meristem is at the tip of shoots
Lateral meristems will be derived from the peripheral zone of the apical meristem

4. Primary vs. Secondary Growth
Secondary growth results in an increase in diameter
Tissues for secondary growth are derived from lateral meristem (cambium)

5. Cambium Cambium is the main living tissue of woody stems
Vascular cambium lies between the xylem and phloem, both of which are derived from it
Cork cambium lies outside of the living phloem, and is derived from phloem and periderm

6. Cambium in Woody Stems Vascular cambium divides the wood from the bark
Cork cambium divides the inner bark from the outer bark

7. Woody Stems: Wood vs. Bark
Wood functions for conducting water and minerals and support
Wood forms the bulk of the woody stem
Wood is made of xylem (Remember, xylem is dead at maturity)
Bark functions for conducting food and for protection of the wood and cambium
Bark contains a variety of tissues:
Living phloem
Dead phloem
Cork
Epidermis

8. Section 1 Review Q’s (p. 106)

9. Chap 5 Objectives (Section 2&3)
5. Distinguish between “anticlinal” and “perclinal” cell divisions. Describe the growth resulting from each type. 6. Define “cavitation”. 7. Distinguish between “sapwood” and “heartwood” 8. Explain annual “growth rings” in wood from the context of secondary growth. 9. Define “suberin” and “lenticels” and discuss their functions 10. Discuss several commercial applications of wood and bark and their derivatives.

10. Patterns of cell division
Anticlinal
Periclinal

11. Cavitation
Xylem tissue is dead, consisting of vessel elements and tracheids
Transmission of water through xylem depends on cohesion through an unbroken column of water molecules.
The water is pulled from above, not pushed from below
Once an air bubble forms in the xylem (usually in the larger vessel elements), called “cavitation” the water below the bubble cannot be drawn up any longer

12. Sapwood vs. Heartwood
Sapwood is xylem that is still functioning for transmission of water. It lies directly below the vascular cambium
Heartwood is no longer conductive due to cavitation. It lies at the center of the woody stem

13. Growth rings
The pattern of cell growth changes over the course of the growing season, resulting in a visible distinction between the secondary growth from one season compared to the next

14. Annual growth patterns
The early growing season is generally warmer and moister with long days
Cells formed in the spring tend to be larger, with thinner walls
Cells formed late in the season are generally smaller.

15. One year old Basswood stem

16. Two year old Basswood stem

17. Three year old Basswood stem

18. Dendrochronology

19. Dendrochronology cores

20. Suberin

21. Lenticels

22. Section 2 Review Q’s (p. 112)