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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 .
A number of different classification systems of the patterns of leaf veins (venation or veination) have been described, [28] starting with Ettingshausen (1861), [53] together with many different descriptive terms, and the terminology has been described as "formidable". [28]
The leaves also possess vascular bundles, which are generally visible as veins, whose patterns are called venation. Leaves tend to have a shorter life span than the stems or branches that bear them, and when they fall, an area at the attachment zone, called the abscission zone leaves a scar on the stem.
2. (of a leaf) Having arched leaf tissue between each lateral vein, i.e. the veins appear depressed in the leaf surface. burl A deformation or knot in the branches or trunk of a tree, sometimes sought after in woodworking. [24] burr 1. A prickly fruit. 2.
A primary vein, also known as the midrib, is the main vascular structure running through the center of a leaf. [1] The primary vein is crucial for the leaf’s efficiency in photosynthesis and overall health, as it ensures the proper flow of materials and structural integrity.
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 ...
With an opposite leaf arrangement, two leaves arise from the stem at the same level (at the same node), on opposite sides of the stem. An opposite leaf pair can be thought of as a whorl of two leaves. With an alternate (spiral) pattern, each leaf arises at a different point (node) on the stem. Distichous leaf arrangement in Clivia
In plant anatomy and evolution a microphyll (or lycophyll) is a type of plant leaf with one single, unbranched leaf vein. [1] Plants with microphyll leaves occur early in the fossil record, and few such plants exist today. In the classical concept of a microphyll, the leaf vein emerges from the protostele without leaving a leaf gap. Leaf gaps ...