Leaves are any of the principle appendages of a vascular plant stem. Usually borne laterally aboveground and specialized for photosynthesis. Leaves are collectively called foliage, as in “autum foliage”. While the leaves, stem, flower, and fruit collectively form the shoot system. In most leaves, the primary pho  Leaves are any of the principle appendages of a vascular plant stem. Usually borne laterally aboveground and specialized for photosynthesis. Leaves are collectively called foliage, as in “autum foliage”. While the leaves, stem, flower, and fruit collectively form the shoot system. In most leaves, the primary pho