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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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Anatomy

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Medium-scale features edit Leaves are normally extensively vascularized and typically have networks of vascular bundles containing xylem, which supplies water for photosynthesis, and phloem, which transports the sugars produced by photosynthesis. Many leaves are covered in trichomes (small hairs) which have diverse structures and functions. Small-scale features edit The major tissue systems present are The epidermis , which covers the upper and lower surfaces The mesophyll tissue inside the leaf, which is rich in chloroplasts (also called chlorenchyma ) The arrangement of veins (the vascular tissue) These three tissue systems typically form a regular organization at the cellular scale. Specialized cells that differ markedly from surrounding cells, and which often synthesize specialized products such as crystals, are termed idioblasts . Major leaf tissues edit Epidermis edit The epidermis is the outer layer of cells covering the leaf. It is covered with a waxy cuticle which is impe...
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Leaf

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A leaf (plural leaves ) is the principal lateral appendage of the vascular plant stem, usually borne above ground and specialized for photosynthesis. The leaves and stem together form the shoot. Leaves are collectively referred to as foliage, as in "autumn foliage". In most leaves, the primary photosynthetic tissue, the palisade mesophyll, is located on the upper side of the blade or lamina of the leaf but in some species, including the mature foliage of Eucalyptus , palisade mesophyll is present on both sides and the leaves are said to be isobilateral. Most leaves are flattened and have distinct upper ( adaxial ) and lower ( abaxial ) surfaces that differ in color, hairiness, the number of stomata (pores that intake and output gases), the amount and structure of epicuticular wax and other features. Leaves are mostly green in color due to the presence of a compound called chlorophyll that is essential for photosynthesis as it absorbs light energy from the sun. A leaf with ...
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