A leaf is the principal lateral appendage of the stem which is in turn part of a plant. Hence a leave is an organ of a vascular plant. The shoot is formed together by the stem and the leaves. Foliage is a term used for referring leaves collectively. As is one must have often heard, 'autumn foliage'. The characteristic of this plant organ is that it is a dorsoventrally flattened organ, usually borne above the ground, and specialised for its function of photosynthesis. Photosynthesis is the process of converting the intake of carbon dioxide into oxygen. The primary photosynthesis tissue, in most leaves, known as palisade mesophyll, is located on the upper side of the blade or lamina of the leaf. However there are still exceptions, like in some species, including the mature foliage of Eucalypts, palisade mesophyll is present on both sides and these leaves are said to be isobilateral.
Many leaves have a distinct upper surface, also known as adaxial and distinct lower surface called abaxial which differ in colour, the number of stomata ( stomata are the pores present on leaves that intake and output gases), hairiness, the amount and structure of epicuticular wax and other features. When talking about the colour of leaves, they are mostly green, but there are always exceptions.
In this sub category you can download free PNG images: Leaf Food. In this category "Leaf" we have 19 free PNG images with transparent background.
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