Leaf

Leaves are the green, thin, flattened lateral outgrowths of the stem, and collectively all the leaves of a plant are called the phyllome. Characteristically a leaf is a lateral appendage of the stem, borne at a node, exogenous in origin, of limited growth, and - unlike the stem - never ends in an apical bud; it has three main parts (leaf base, petiole and lamina), and its lamina is traversed by vascular strands called veins. Leaves are the plant's primary photosynthetic organs and its main site of transpiration; their primary functions are photosynthesis, transpiration, gaseous exchange, protecting the buds in their axil, and conducting water and dissolved solutes. Beyond these, leaves take on secondary functions through modification: storage (Aloe, Agave, Kalanchoe, Sedum, Brassica oler …