Leaves have several key parts that allow them to efficiently perform photosynthesis. The blade is the main structure that collects sunlight, while the petiole attaches the blade to the stem. Within the blade are a midrib and veins that transport water and nutrients. The edge of the leaf is called the margin. A simple leaf has one continuous blade, while a compound leaf's blade is divided into sections. The four main types of venation patterns are parallel, pinnately netted, palmately netted, and dichotomous. Gas exchange occurs through stomata on the lower epidermis, which are controlled by guard cells.
6. Main Parts of a Leaf Tip/Apex Midrib Margin Veins Base Petiole Blade Leaf Courtesy of Corinne Banowski
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9. Types of Compound Leaves Odd Pinnately Compound Even Pinnately Compound Palmately Compound Courtesy of Wm. C. Brown Publishers
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12. Types of Leaf Venation Parallel Netted Veins Pinnately Netted Veins Palmately Netted Veins Courtesy of Wm. C. Brown and McGraw Hill Publishers Dichotomous Netted Veins
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16. Internal Parts of A Leaf Petiole Blade Cuticle Upper Epidermis Palisade Mesophyll Vein Spongy Mesophyll Lower Epidermis Guard Cell Stomata Air Spaces Stoma, singular Courtesy of Wm. C. Brown Publishers
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Notes de l'éditeur
Some examples of these types of trees are: Odd pinnate = Green Ash Even pinnate = Common Thornless Honeylocust Palmately = Umbrella Schefflera
You can use this slide as review with the students. The order of the layers is: Cuticle Upper Epidermis Palisade Mesophyll Spongy Mesophyll Stomate Guard Cell
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