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Structure of leaf and plant.DIAGRAM of astivation.

• Epidermis – Outer layer of tissues.
• Cuticle – Waxy protective outer layer of epidermis that prevents water loss on leaves, green stems, and fruits.  The amount of cutin or wax increases with light intensity.
  

•     Leaf hairs – part of the epidermis

•     Palisade layer – A tightly packed layer of parenchyma tissues filled with chloroplasts for photosynthesis.

•     Chloroplasts – Sub-cellular, photosynthetic structures in leaves and other green tissues.  Chloroplasts contain chlorophyll, a green plant pigment that captures the energy in light and begins the transformation of that energy into sugars.

•  Vascular bundle – Xylem and phloem tissues, commonly known as leaf veins.

•   Spongy mesophyll – Layer of parenchyma tissues loosely arranged to facilitate movement of oxygen, carbon dioxide, and water vapor.  It also may contain some chloroplasts.

•   Stomata – Natural openings in leaves and herbaceous stems that allow for gas exchange (water vapor, carbon dioxide, and oxygen).

•     Guard cells – Specialized kidney-shaped cells that open and close the stomata.

Fig 1:- Leaf cross section with stomata.

II. External Features

•     Leaf blade – Flattened part of the leaf

•     Petiole – Leaf stalk

•     Stipules – Leaf-like appendages at the base of the leaf.

 Fig:- 2.  Leaf external features.