Unformatted text preview: layered hypodermis • The epidermis is covered with a waxy cuticle (thickness varies). • Epidermis Functions Protection Gas exchange • Special cells in leaf epidermis Guard cells that form stomata • Guard cells are concentrated on lower epidermis in most leaves. Guard cells are most often pairs of "bean-shaped" cells with thick, rigid inner walls. They contain chloroplasts. The opening between guard cells forms stomata for gas exchange • Stomata open and close with changes in turgor caused by solute differences between the guard cells and the surrounding epidermal cells. The thinner walls of the guard cell stretch as it swells with water whereas the thicker, inner walls do not. This differential stretching creates the stoma. Chemical signals, photosynthesis and osmotic changes are necessary for most stomatal function. We will discuss this mechanism later....
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- Fall '09
- Photosynthesis, guard cells, lower epidermis, leaf epidermis