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General Features of the Lamina (Blade) |
| Three Tissue Systems are present!
Epidermal - Ground (Mesophyll in leaves) - Vascular (Veins) |
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Leaf Anatomy - Lamina or Blade |
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| The Adaxial Epidermis
generally has a thick cuticle on the upper (adaxial) surface. Secretory &
Non-secretory Trichomes may be present. Stomata may occur on the upper epidermis but these
are most frequent on the lower (abaxial) surface. The Abaxial Epidermis usually has a thin cuticle. However, it may have a dense layer of trichomes which increase the "boundary layer" effect which decreases the rate of transpiration. Stomata are routinely present on the abaxial surface and are usually more abundant than on the adaxial surface. |
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Lamina from Ohia' lehua Metrosideros polymorpha showing a thick adaxial cuticle (C) and abaxial Trichomes (T) |
Same but with Polarizing Optics. This brings out trichomes, crystals and cells with thick, highly organized Cell Walls |
Mesophyll |
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| Palisade mesophyll is composed of columnar cells that can be one to several layers thick. It is most common on the adaxial side of the leaf where sunlight is usually most abundant. Palisade parenchyma are more efficient for photosynthesis and water retention because of their large surface areas but small intercellular air spaces. |
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| Spongy mesophyll is usually found on the abaxial side of the leaf. It may consist of stellate parenchyma or chains of elongate cells which have large, lateral intercellular spaces. |
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| Some plants have a uniform mesophyll which is composed of relatively isodiametric cells. |  Mesophyll Cells in Wheat do not have pronounced shapes, and give a uniform appearance. |
| Nerium oleander (Oleander) has pronounced Palisade and Spongy Layers |
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