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Chapter 6 (External Structures of Foliage Leaves (Photosynthesis is a…
Chapter 6
External Structures of Foliage Leaves
Photosynthesis is a function of foliage
Photosynthesis
Leaves must lose excessive amounts of water
Leaves absorb carbon dioxide and convert it to carbohydrates by light energy
A Leaf Blade is Flat and Harvests light
Lamina
Another Name for Leaf Blade
Lower side of the blade is its dorsal surface
Larger Veins protrude like backbones and are called the abaxial sides
The upper side is called the ventral surface
The petiole stalk holds the blade out into the light
Plant Diagram
A small leaf that is long and narrow, has no problem shading and is called a sessile leaf
The leaf base wrapping around the stem to forma sheathing leaf base
A leaf blade can be either simple or compound
compound leaf has a blade divided into several individual parts
The small blades are called leaflets
A petiolule attaches leaflets to an extension of the petiole
A rachis is an extension of a petiole
Abscission Zone is at the leaf base usually in the petiole
Internal Structure of Foliage Leaves
Transpiration is the loss of water through the epidermis
Ground tissue interior to the leaf epidermis are collectively called mesophyll
Along the upper surface of most leaves is a layer of cells is the palisade parenchyma
The lower portion of the leaf contains the spongey mesophyll
A midrib is located in the eudicot and also called a mid vein
Lateral Veins
Emerge From
Minor veins emerge from Lateral Veins
Emerges from
Many fibers aranged as a sheath is a bundle sheath
Bundle Sheath Extension
Leaf Traces
1,3, 5, or more vascular tissue
Stipules
Two small flaps of tissue
Morphology and Anatomy of Other Leaf Types
Bud scales are one of the most common modifications of leaves
Sclerophyllous Leaves
Foliage leaves must produce more sugars
Leaves of Conifers are sclerophyllus
This type of cell
Cactus Spines are modified leaves of axillary buds
A tendril is a form of a modified leaf
Initiation and Development of leaves
Leaf primordium is protussion of cells
Monocots are initiated by the expansion of shoot apical meristem cells
Broad succulent stems store water
