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A vascular bundle is a part of the transport system in vascular plants. The transport itself happens in the stem, which exists in two forms: xylem and phloem. Both these tissues are present in a vascular bundle, which in addition will include supporting and protective tissues. There is also a tissue between xylem and phloem, which is the cambium.
Vascular tissue is a complex conducting tissue, formed of more than one cell type, found in vascular plants. The primary components of vascular tissue are the xylem and phloem. These two tissues transport fluid and nutrients internally. There are also two meristems associated with vascular tissue: the vascular cambium and the cork cambium. All ...
Among living plants, this type of stele is found only in the stems of ferns. Most seed plant stems possess a vascular arrangement which has been interpreted as a derived siphonostele, and is called a eustele – in this arrangement, the primary vascular tissue consists of vascular bundles, usually in one or two rings around the pith. [12]
Tracheids were the main conductive cells found in early vascular plants. In the first 140–150 million years of vascular plant evolution, tracheids were the only type of conductive cells found in fossils of plant xylem tissues. [5] Ancestral tracheids did not contribute significantly to structural support, as can be seen in extant ferns. [6]
Most of the vascular cambium is here in vascular bundles (ovals of phloem and xylem together) but it is starting to join these up as at point F between the bundles. The vascular cambium is the main growth tissue in the stems and roots of many plants, specifically in dicots such as buttercups and oak trees, gymnosperms such as pine trees, as ...
The side walls of a vessel element have pits: more or less circular regions in contact with neighbouring cells. Tracheids also have pits, but only vessel elements have openings at both ends that connect individual vessel elements to form a continuous tubular vessel. These end openings are called perforations or perforation plates.
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The cortical bundle emerges radially from the xylem and produces shoots that run tangentially to the cortex, branching extensively and vascularizing every part of the cortex. [1] The size of the cortical bundle can vary greatly from species to species. [2] Because cacti live a long time, the cortical bundles have to function for many years.