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Vascular tissue

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**Components of Vascular Tissue:**
Vascular tissue in plants consists of xylem and phloem.
– Xylem and phloem transport fluid and nutrients internally.
– Vascular cambium and cork cambium are meristems associated with vascular tissue.
Vascular tissue system in a plant comprises all its vascular tissues.
Vascular tissue cells are long, slender, and function in fluid conduction.

**Arrangement of Vascular Tissue:**
Vascular tissue forms long strands called vascular bundles.
– Vascular bundles include xylem, phloem, and supporting cells.
– In stems and roots, xylem is closer to the interior, while phloem is towards the exterior.
– Some dicot stems may have phloem inwardly from xylem in Asterales.
– Vascular cambium lies between xylem and phloem, producing new cells for growth.

**Functions of Vascular Cambium:**
– Vascular cambium increases plant girth through cell division.
– It allows for the production of woody growth in trees.
Cork cambium develops among phloem to protect the plant’s surface.
– Production of wood and cork are forms of secondary growth.
– Vascular cambium maintains plant growth as long as it produces new cells.

**Vascular Tissue in Leaves:**
– Vascular bundles in leaves are located among spongy mesophyll.
– Xylem faces the upper leaf surface, while phloem faces the lower leaf surface.
– Aphids are typically found on the lower leaf surface due to phloem location.
Vascular tissue in leaves transports sugars manufactured by the plant.
– Vascular bundles in leaves are crucial for nutrient transport.

**Related Topics:**
– Xylem and phloem are key components of vascular tissue.
Cork cambium and vascular cambium are associated with vascular tissue growth.
– Stele in biology is related to the structure of vascular tissue.
– Vascular plants rely on vascular tissue for internal transport.
– Understanding the circulatory system helps comprehend vascular tissue function.

Vascular tissue (Wikipedia)

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 the vascular tissues within a particular plant together constitute the vascular tissue system of that plant.

Cross section of celery stalk, showing vascular bundles, which include both phloem and xylem
Detail of the vasculature of a bramble leaf
Translocation in vascular plants

The cells in vascular tissue are typically long and slender. Since the xylem and phloem function in the conduction of water, minerals, and nutrients throughout the plant, it is not surprising that their form should be similar to pipes. The individual cells of phloem are connected end-to-end, just as the sections of a pipe might be. As the plant grows, new vascular tissue differentiates in the growing tips of the plant. The new tissue is aligned with existing vascular tissue, maintaining its connection throughout the plant. The vascular tissue in plants is arranged in long, discrete strands called vascular bundles. These bundles include both xylem and phloem, as well as supporting and protective cells. In stems and roots, the xylem typically lies closer to the interior of the stem with phloem towards the exterior of the stem. In the stems of some Asterales dicots, there may be phloem located inwardly from the xylem as well.

Between the xylem and phloem is a meristem called the vascular cambium. This tissue divides off cells that will become additional xylem and phloem. This growth increases the girth of the plant, rather than its length. As long as the vascular cambium continues to produce new cells, the plant will continue to grow more stout. In trees and other plants that develop wood, the vascular cambium allows the expansion of vascular tissue that produces woody growth. Because this growth ruptures the epidermis of the stem, woody plants also have a cork cambium that develops among the phloem. The cork cambium gives rise to thickened cork cells to protect the surface of the plant and reduce water loss. Both the production of wood and the production of cork are forms of secondary growth.

In leaves, the vascular bundles are located among the spongy mesophyll. The xylem is oriented toward the adaxial surface of the leaf (usually the upper side), and phloem is oriented toward the abaxial surface of the leaf. This is why aphids are typically found on the undersides of the leaves rather than on the top, since the phloem transports sugars manufactured by the plant and they are closer to the lower surface.[citation needed]

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