- Leaf is a complex structure designed to maximize photosynthesis & minimize H2O loss.
- Composed of 2 major systems.
- Dermal System
- Fundamental System
- Functions to allow gas exchange & protect plant
- Composed of Cuticle & Epidermis
- Cuticle is a waxy waterproof layer
- Reduces water loss
- Prevents parasites from entering plant
- Epidermis is the outermost layer of cells of the leaf
- Contain unusual structures called stomata
- Stomata are openings allowing gas exchange in/out of leaf
- Are opened and closed by function of 2 guard cells
- In high heat or arid conditions guard cells close stomates reducing water loss
Stomates
Fundamental System - Also known as the Mesophyll
- Contains 2 major tissue layers
- Palisade parenchyma
- Major fxn: Photosynthesis
- Spongy parenchyma
- Fxn: some photosynthesis, also storage and transport
- Mesophyll also contains vascular bundles consisting of
- Bundle sheath
- Xylem & phloem
Cross Section of a Leaf
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