1. Leaf Structure
Vascular plants

2. Leaf Boundaries Lower Epidermis Upper Epidermis Cuticle
Layer of cells that forms the bottom of the leaf
Upper Epidermis
Layer of cells that forms the top of the leaf
Cuticle
Thick, waxy layer on exposed cells of epidermis; protects against water loss & injury

3. Mesophyll- palisade layer + spongy layer; where photosynthesis takes place
Tall, column-shaped cells just under the upper epidermis
Spongy layer
Loose tissue beneath palisade layer; air spaces between cells

4. Air space Chloroplasts Open space in between cells in the spongy layer
Organelle in plant cells that captures energy from sunlight & converts it to chemical energy

5. Do the cells of the Epidermis have chloroplasts?

6. Specialized parts in the lower epidermis
Stoma (plural = stomata)
Opening in underside of leaf; allows CO2 & O2 to diffuse in & out
Guard cells
Controls the opening & closing of stomata by responding to changes in water pressure

7. What happens if the stomata stay open all the time?
Transpiration
Loss of water through leaves when stomata open

8. Vein (vascular bundle)- cluster of vascular tissues (xylem + phloem)
Carries water upward from roots to every part of the plant
Phloem
Transports nutrients down produced by photosynthesis (food)

9. Vein & vascular tissue
What does water pressure have to do with water circulation through the plant?
Hint: what part of the leaf responds to water pressure?

10. Deep thoughts:
What weather conditions might cause more transpiration to occur? How about less?
What specific carbohydrate does phloem carry down?
Why is there air space in between spongy layer cells?