Venation (botany)

A leaf ( : leaves) is any of the principal appendages of a

vascular plant Vascular plants (), also called tracheophytes () or collectively Tracheophyta (), form a large group of land plants ( accepted known species) that have lignified tissues (the xylem) for conducting water and minerals throughout the plant. They ...

stem, usually borne laterally aboveground and specialized for

photosynthesis Photosynthesis is a process used by plants and other organisms to convert light energy into chemical energy that, through cellular respiration, can later be released to fuel the organism's activities. Some of this chemical energy is stored i ...

. Leaves are collectively called foliage, as in "autumn foliage", while the leaves, stem, flower, and fruit collectively form the

shoot In botany, a plant shoot consists of any plant stem together with its appendages, leaves and lateral buds, flowering stems, and flower buds. The new growth from seed germination that grows upward is a shoot where leaves will develop. In the sp ...

system. In most leaves, the primary photosynthetic tissue is the

palisade mesophyll Palisade cells are plant cells located on the leaves, right below the epidermis and cuticle that is the outermost layer of the leaf. In simpler terms, they are known as leaf cells. Palisade means "stake" in latin, they are vertically elongated an ...

and is located on the upper side of the blade or lamina of the leaf but in some species, including the mature foliage of ''

Eucalyptus ''Eucalyptus'' () is a genus of over seven hundred species of flowering trees, shrubs or mallees in the myrtle family, Myrtaceae. Along with several other genera in the tribe Eucalypteae, including '' Corymbia'', they are commonly known as e ...

'', palisade mesophyll is present on both sides and the leaves are said to be isobilateral. Most leaves are flattened and have distinct upper (

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