Plant Structures: Leaves
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Transcript of Plant Structures: Leaves
Plant Structures: Leaves
What is a leaf?• Leaves are structures produced on stems wherephotosynthesis primarily takes place.Functions:• Photosynthesis• Evapotranspiration (loss of water vapor from the stomata) moves water and nutrients up from the roots.• Small openings in the leaf (stomata) regulate moisture and gas exchange and temperature in the plant.• Used for feed and food.• Habitat for some organisms• Used for plant identification• Used for asexual reproduction (cuttings)
External structure:
Blade = Broad and flat part of the leaf where most of the photosynthesisof the plant takes place.
Petiole = The thin stalk that connects the leaf to the stem.
Stipule = An outgrowth at the base of the petiole – can be in pairs; can vary and be in the form of glands, scales, hairs, spines and sometimeslook leaf-like.
Internal structure:
Waxy coating – prevents water loss – can be thicker in desert plants
Tightly packed parenchyma cells filled with chloroplasts
Vascular bundle/ leaf veins - moves water and nurients through the plantParenchyma cells
looselyarranged, help with movement of O2, CO2 and water vapor. May contain chloroplasts
Openings that allow for gas exchange (water vapor, O2, CO2)
Specialized kidney shaped cells that open and close the stomata
Epidermis – Upper – Protect underlying tissues, could have a waxy coating to prevent water loss.Lower – Contains stomata
Blade
Leaflets
Simple leaf
Compound leafDouble/Doubly compound leaf
Leaflet
Compound leaf
Simple leaf
Doubly compoundleaf
Pinnatevenation
Alternate
Whorled
Opposite