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Evolutionary adaptation

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In the course of evolution, leaves have adapted to different environments in the following ways: citation needed Waxy micro- and nanostructures on the surface reduce wetting by rain and adhesion of contamination ( See Lotus effect ). Divided and compound leaves reduce wind resistance and promote cooling. Hairs on the leaf surface trap humidity in dry climates and create a boundary layer reducing water loss. Waxy plant cuticles reduce water loss. Large surface area provides a large area for capture of sunlight. In harmful levels of sunlight, specialized leaves, opaque or partly buried, admit light through a translucent leaf window for photosynthesis at inner leaf surfaces (e.g. Fenestraria ). Kranz leaf anatomy in plants who perform C4 carbon fixation Succulent leaves store water and organic acids for use in CAM photosynthesis. Aromatic oils, poisons or pheromones produced by leaf borne glands deter herbivores (e.g. eucalypts). Inclusions of crystalline minerals deter herbivor...
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General characteristics

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Leaves are the most important organs of most vascular plants. Green plants are autotrophic, meaning that they do not obtain food from other living things but instead create their own food by photosynthesis. They capture the energy in sunlight and use it to make simple sugars, such as glucose and sucrose, from carbon dioxide and water. The sugars are then stored as starch, further processed by chemical synthesis into more complex organic molecules such as proteins or cellulose, the basic structural material in plant cell walls, or metabolized by cellular respiration to provide chemical energy to run cellular processes. The leaves draw water from the ground in the transpiration stream through a vascular conducting system known as xylem and obtain carbon dioxide from the atmosphere by diffusion through openings called stomata in the outer covering layer of the leaf (epidermis), while leaves are orientated to maximize their exposure to sunlight. Once sugar has been synthesized, it needs to...
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Leaf development

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According to Agnes Arber's partial-shoot theory of the leaf, leaves are partial shoots, being derived from leaf primordia of the shoot apex. Early in development they are dorsiventrally flattened with both dorsal and ventral surfaces. Compound leaves are closer to shoots than simple leaves. Developmental studies have shown that compound leaves, like shoots, may branch in three dimensions. On the basis of molecular genetics, Eckardt and Baum (2010) concluded that "it is now generally accepted that compound leaves express both leaf and shoot properties."
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