1. Leaves 23.1.1 Describe the organs and tissues of vascular plants.
Identify the specialized cells of vascular tissue.
contrast meristematic tissue with other plant tissues.

2. 3 principal organs and tissues of seed plants
Roots
Absorbs water and dissolved nutrients.
Anchor plants in the ground
Protect plants from harmful soil bacteria and fungi
Transport water and nutrients to the rest of the plant
Stems
Has a: support system- for the plant body, transport system-carries nutrients, and a defense system-protects the plant against predators and disease.
Leaves
Main photosynthetic systems
Help conserve water while letting oxygen and carbon dioxide enter and exit the leaf.

3. Figure 23–1 Page 580 Root, Stem, and Leaf Tissues
Leaves, stems, and roots
What are the 3 principal plant organs?
Leaf
Stem
Which tissue is found in the center of a plant stem?
Ground tissue
Root
Dermal tissue
Vascular tissue
Ground tissue
Three main tissue systems

4. Concept Map Plant Tissues Section 23-1 include Dermal tissue
Meristematic tissue
Vascular tissue
Ground tissue
includes
includes
includes
Epidermal cells
Parenchyma cells
Collenchyma cells
Schlerenchyma cells
Xylem
Phloem
includes
includes
Companion cells
Vessel elements
Sieve tube elements
Tracheids

5. Roots 23-2 2 main types Taproots Fibrous
Primary root that grows thicker and longer than others
Example: carrots, dandelions, beets, and radishes
Fibrous
Branch to such an extent that no single root grows larger than the rest
Example: grasses
How do roots help prevent erosion?
Extensive, branching fibrous roots hold soil in place.

6. Figure 23–7 The Structure of a Root
Section 23-2
Epidermis
Endodermis
Root hairs
Ground tissue (cortex)
Vascular Cylinder
Ground tissue (cortex)
Epidermis
Endodermis
Vascular cylinder
Phloem
Xylem
Zone of maturation
Zone of elongation
Apical meristem
Cross Section of Plant Root (magnification: 40x)
Root cap

7. Stems 23-3 3 functions Produce leaves, branches, and flowers
Hold leaves up to the sunlight
They transport substances between roots and leaves

8. 23.4.2 Describe how gas exchange takes place in a leaf.
Leaves 23-4
Objective
Describe how the structure of a leaf enables it to carry out photosynthesis.
Describe how gas exchange takes place in a leaf.
Read Pages

9. 23-4 What is the main function of a plant’s leaf?
The leaves of a plant are its main organs of
photosynthesis.
How does the structure of a leaf enable it to carry out photosynthesis?
The structure of a leaf is optimized for
absorbing light and carrying out
How does gas exchange take place in a leaf?
Plants leaves allow gas exchange by opening their stomata.

10. Leaf Functions Photosynthesis Transpiration Gas Exchange
the loss of water through its leaves
Gas Exchange
Plants keep their stomata open just enough to allow photosynthesis to take place but not so much that they lose an excessive amount of water.

11. Stomata - Porelike openings in the underside of the leaf that allow carbon dioxide and oxygen to diffuse in and out of the leaf.
Each stomata has 2 guard cells.
Guard Cells - epidermal cells found on the underside of leaves that control the opening and closing of the stomata by responding to changes in water pressure. Also, responds to conditions in the environment, such as wind and temperature.

12. Stomata
When the guard cells are swollen with water, the stomata is opened.
When the guard cells lose water, the stomata closes.
Are open during the daytime, when photosynthesis is active.
Are closed at night to prevent water loss.
May be closed during bright sunlight under hot, dry conditions in which the plant needs to conserve water to survive.

13. Function of Guard Cells
Inner cell wall
Inner cell wall
Stoma
Stoma Open
Stoma Closed

14. Function of Guard Cells
Section 23-4
Guard cells
Guard cells
Inner cell wall
Inner cell wall
Stoma
Stoma Open
Stoma Closed
What factor regulates the opening and closing of stomata?
Changes in water pressure within guard cells