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A leaf (pl.: leaves) is a principal appendage of the stem of a vascular plant, [1] usually borne laterally above ground and specialized for photosynthesis.Leaves are collectively called foliage, as in "autumn foliage", [2] [3] while the leaves, stem, flower, and fruit collectively form the shoot system. [4]
A tree structure, tree diagram, or tree model is a way of representing the hierarchical nature of a structure in a graphical form. It is named a "tree structure" because the classic representation resembles a tree , although the chart is generally upside down compared to a biological tree, with the "stem" at the top and the "leaves" at the bottom.
Leaves of most plants include a flat structure called the blade or lamina supported by a network of veins, a petiole and a leaf base; [1] but not all leaves are flat, some are cylindrical. [ citation needed ] Leaves may be simple, with a single leaf blade, or compound, with several leaflets .
English: The medium scale structure of a leaf featuring the major tissues; the upper and lower epithelia (and associated cuticles), the palisade and spongy mesophyll and the guard cells of the stoma. Vascular tissue (veins), made up of xylem, phloem and sheath cells, and example trichromes are also shown.
For example, the leaves of pine, oak, and cabbage all look very different, but share certain basic structures and arrangement of parts. The homology of leaves is an easy conclusion to make. The plant morphologist goes further, and discovers that the spines of cactus also share the same basic structure and development as leaves in other plants ...
Vein – the externally visible vascular bundles found on leaves, petals, and other parts. Veinlet – a small vein. Leaf Arrangement or Phyllotaxy: Whorl – three or more leaves or branches or pedicels arising from the same node. Leaf Type: Abruptly pinnate – a compound leaf without a terminal leaflet. Leaf Blade Shape:
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An unrooted binary tree on n labeled leaves can be formed by connecting the nth leaf to a new node in the middle of any of the edges of an unrooted binary tree on n − 1 labeled leaves. There are 2 n − 5 edges at which the n th node can be attached; therefore, the number of trees on n leaves is larger than the number of trees on n − 1 ...