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Common functions
- photosynthesis
- defense
- climbing
- storage
- prey capture
- pollinator attraction
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photosynthesis requires light water and carbon dioxide
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blade
- flattened
- photosynthesis occurs
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petiole
- connects blade to stem.
- vascular connections
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veins
provide conduction and support
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simple
leaf blade undivided
-
compound
leaf blades divided into leaflets
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internal structure of leaves
- epidermis
- mesophyll
- vascular bundles
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leaf epidermis cell types
- typical epidermal cell (lightly packed parenchyma)
- trichomes-specialized outgrowths of epidermis
- guard cells-open and close pores to regulate water vapor
-
typical epidermis cell
- tightly packed parenchyma
- lacks chloroplasts
- located in the epidermis
-
trichomes (epidermis)
- specialized outgrowths of epidermis
- these are often lacking
- secretary glands
- sharp
- shield stomata
- reflect light
-
guard cells (epidermis)
- function in pairs to open and close stomata
- regulates water vapor
- located in leaves
- have chloroplasts
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mesophyll
- chloroplasts rich parenchyma between upper and lower epidermis; photosynthetically active
- palisade mesophyll-beneath upper epidermis
- spongy mesophyll- parenchyma beneath palisade
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vascular bundles
- provide conduction and physical support; found throughout mesophyll
- veins are surrounded by a bundle sheath, ensuring no part of vein is directly exposed to air spaces
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Leaf abscission
- chemical and structural changes occur at leaf base
- protective layer of dead, waterproof cells forms toward interior, sealing it
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