Jim Bidlack - BIO 5354/4354 PLANT ANATOMY Lecture 23 - Leaf Structure I. Leaf cross section of a terrestrial dicot A. Axiality of the leaf 1. Leaf axil is found at the primordia - stem junction a) Adaxial - closest to the axal (ends up to be upper leaf surface) b) Abaxial - away from the axal (ends up to be lower leaf surface) B. Leaf anatomy (from the upper to the bottom surface) 1. Adaxial epidermis - upper epidermis, often cutinized 2. Palisade parenchyma/mesophyll - major photosynthetic tissue 3. Spongy parenchyma/mesophyll - less photosynthetic tissue, allows gas exchange a) Abundant in aerenchyma and some chlorenchyma 4. Vascular bundle (usually in spongy mesophyll) a) Xylem on top and phloem on the bottom 5. Abaxial epidermis - lower epidermis, has stomata (and substomatal chambers) II. Variations in angiosperm leaf anatomy A. Palisade layer 1. Number of layers related to light (more light, more palisade) B. Bundle sheath extension NOTE:
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