sieve-tube cells (also called sieve-tube elements) are arranged end to end to make
up a long sieve tube, which transports organic substances such as sugars and amino acids. Sugars
flow from one sieve tube cell to the next via perforated sieve plates found at the end junctions of two
cells. The nucleus and other cell components of the sieve-tube cells have disintegrated despite the
fact that they were still alive at maturity.
Companion cells are found alongside the sieve-tube cells,
providing them with metabolic support. The sieve-tube cells have fewer ribosomes and mitochondria
than the companion cells, which lack some cellular organelles.
Ground Tissue Ground tissue is primarily composed of parenchyma cells, but it may also contain
collenchyma and sclerenchyma cells, which aid in the support of the stem. The pith is the ground
tissue towards the interior of the vascular tissue in a stem or root, while the cortex is the layer of tissue
between the vascular tissue and the epidermis

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Key definitions Meristem – a formative plant tissue composed of tiny cells capable of proliferating forever and producing
similar cells or cells that differentiate to generate the final tissues and organs
Tissue – a collection of cells, generally of a certain kind, and their intercellular substance that forms one of the
structural components of a plant or animal
Vascular – relating to, or influencing a route for the conveyance of a bodily fluid (such as animal blood or
plant sap) or a system of similar channels
Valuable – possessing desirable or respected features or attributes
Exchange – the act or practice of replacing one item with another