1. Chapter 23 Plant Structure and Function
Tissue systems and growing regions
Roots
Stems
Leaves

2. Tissue Systems
Ground system
Vascular system
Dermal tissue system

3. Vascular and Dermal Systems
Xylem conducts water and minerals
Phloem conducts food
Dermal
Epidermis: outer layer of cells

4. Ground System Parenchyma tissue: food storage
Collenchyma tissue: growing regions of the plant
Sclerenchyma: at maturity is made of dead cells that support and strengthen the plant
Ground System

5. Meristems: growing regions where cells divide
Apical Meristem: the tips of stems and roots (result of primary growth)
Lateral meristem: the circumference grows (result of secondary growth)
Cork cambium and vascular cambium
Herbaceous Plants have no vascular cambium so are nonwoody
Woody Plants are perennial (adapted for growth year after year) so they produce secondary xylem.

6. Roots: Structure Root tip – 3 regions
Region of cell division
Region of elongation
Region of maturation
Root cap: composed of cells that protect the apical meristem

7. Roots: primary growth Root hairs increase surface area for absorption
Cortex: storage tissue for the young root
Vascular cylinder: contains xylem and phloem

8. Roots: secondary growth
Occurs when a vascular cambium forms between the primary xylem and phloem.
Provides strength and support for the plant stem.

9. Roots: Functions Absorption of water and inorganic nutrients
The amount of water absorbed depends on the amount lost through transpiration which is the evaporation of water from stems and leaves.
Food storage
Anchors the plant

10. Stems: Structure Primary Growth
Stems only grow at the apical meristem
Dermal tissue protects the stem
Ground tissue forms a cortex and a pith (in gymnosperms and dicots)
Vascular bundles: xylem and phloem
Monocots: bundles are scattered throughout ground tissue
Dicots: bundles occur in a single ring

11. Stems: secondary growth
Stems increase in thickness due to cell division in the vascular cambium (production of more secondary xylem is wood).
Rays are sheets of cells that radiate from the stem center storing food and transporting water laterally across the xylem
Annual rings develop because of water differences among seasons
Bark is the outer layers that protect a plant and consists of cork, cork cambium, cortex and secondary phloem.

12. Secondary Growth in Stem

13. Stems: Functions Support Food Transport: Water Transport: Storage
Food: sugar moves from source to sink
Pressure-flow hypothesis (diffusion) explains this
Water Transport:
Transpiration-cohesion theory – osmosis and cohesion
Storage
Photosynthesis

14. Leaves: Structure Leaves are the result of only primary growth
Parts: blade and petiole

15. Leaves: internal structure
Epidermis: impermeable layer that only allows water, oxygen and carbon dioxide to pass
Mesophyll: chloroplast-rich parenchyma cells
Palisade mesophyll lies directly below the epidermis
Spongy mesophyll lies between the palisade and lower epidermis
Vascular tissue is contained in veins surrounded by bundle sheaths.

16. Leaf cross section:

17. Leaves: Functions Capturing light Gas exchange:
Guard cells surrounding openings called stomata
Opening and closing regulated by turgor pressure
1)When guard cells have water – guard cells expand and create a pore
2) When guard cells have lost water, they shrink and close the pore