Back to 9.1 Structure of Plants
9.1.3 Explain the relationship between the distribution of tissues in the leaf and the functions of these tissues.
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1. Palisade Mesophyll
- Located in the upper portion of the leaf where light is most available. The cells of this region are chlorosplast rich, thus allowing for maximal photosynthesis
2. Veins
- Distributed througout the leaf so as to transport raw materials and products of photosynthesis. The veins occur roughly in the middle of the leaf so as to be near all cells.
3. Spongy Mesophyll
- Located just superior to the stomata allowing continuous channels for gas exchange (loosely packed, surfaces for gas exchange)
4. Stomatal Pores
- Located on the bottom surface of the leaf. This area receives less light with a resulting lower temperature. The lower temperature minimizes water loss from the pores and the plant, thus the lower epidermis usually has a thinner cuticle than the upper epidermis. Guard cells open and close, controlling water loss by transpiration and allowing gas exchange.
5. Cuticle (waxy layer) Upper Epidermis
- The positioning of epidermis is such that the remaining structures of the leaf are protected and supported. It also prevent water loss.
6. Lower Epidermis
- Contains the stomatal pores which allow gas exchange with the leaf
7. Phloem
- Transports the products of photosynthesis (sugars, amino acids)
8. Xylem
- Transports water and minerals into the leaf tissue from the stem and roots
9. Vascular Bundle
- Xylem and Phloem tissues combine in the vascular tissue to provide support to the leaf.