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Leaves. Ch 6 (External Structure of Foliage Leaves. (Leaf blade is the…
Leaves. Ch 6
External Structure of Foliage Leaves.
Leaf blade is the light-harvesting portion
Dorsal surface is the blades lower side
Function is photosynthesis
Ventral surface is the upper side and is usually smooth
Petiole holds the blade out onto the light
If there is no petiole then its a sessile leaf
Leaf blades can be either simple or compound
A leaf can have veins or bundles of vascular tissue
Internal Structure of Foliage Leaves
Epidermis
Waterproof but also translucent
flat,tubular,ordinary epidermal cells, guard cells, and trichomes
Hairy
Contain coating of cutin and wax on their outer walls.
Mesophyll
Ground tissue interior to the leaf epidermis
Palisade parenchyma is the main photosynthetic tissue of most plants
Lower part of the leaf is the spongy mesophyll
loose aerenchyma that permits carbon dioxide to diffuse rapidly away from the stomata into all parts
Vascular tissue
Found between the spongy mesophyll and palisade parenchyma
Petiloe
Transition between the stem and the lamina
Some can be tiny, others can be huge depends on the plants
Stipules are two small flaps of tissueat the base
Initiation and Development of Leaves
Basal Angiosperms and Eudicots
Leaf primordium is when cells grow outward to form a protrusion
Cells are meristematic
Leaves are produced through the activity of apical meristem
Monocots