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Leaf [ Botany ]

Dictionary of botanic terminology - index of names

     
  A leaf is an outgrowth from a node on a plant's stem and come in many shapes and sizes, they are often green and flattened to maximise their surface area for the capture of energy from sunlight and exchange gases,  that are used for photosynthesis by means of the chlorophyll  pigment contained in chloroplasts.  

Leaves vary greatly from plant to plant and are useful in classification and identification. Some leaves also store food and water, provide support, or form new plants. Where high light intensities are harmful, leaves may reduce the effects of the light by orientating themselves vertically; by becoming thickened or covered with hairs or wax or by having a highly reflective surface.

Leaf Parts: Any of these parts may be lacking,  modificate or reduced. Lamina: The expanded portion or blade of a leaf.
Leaf apex: The tip of a leaf opposite to the petiole
Midrib The the central vein of a leaf  it is usually continuous with the petiole.
Vein: The vascular structures on a leaf which  arrangement is called
venation
Petiole: The stalk or stem that connects the leaf to the plant, frequently with a basal enlargement called pulvinus (petiole are absent in sessile leaves)
Axil: The angle between the upper side of the stem and a leaf or petiole
Stem
(also called the axis) from which the leaves arise.
Stipule: The pair of small, appendages one on each side at the base of the petiole.

The forms of leaves lamina vary greatly from plant to plant and are useful in classification and identification.
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