Xylem cells make up the vascular system of plants, circulating water throughout the plant.
A xylem cell is a cell responsible for providing support to a plant. These cells also make up the vascular system of plants, carrying water throughout the plant and providing circulation. These cells can be both alive and dead, and there are several different types of xylem cells that can be found in the parts of a plant collectively known as the xylem.
Lignin makes cell walls rigid.
Plant cells start out as undifferentiated parenchymal cells. These cells can store energy for the plant and can also differentiate and mature into various cell types, including xylem cells. Plant xylem often contains multiple parenchyma cells, which leads some people to classify them as a xylem cell type, although this is technically incorrect.
When a xylem cell dies, it can still act as part of a support network for the plant, because the lignin in the cell walls is intact.
Support is created through tracheas and fibers, cells that contain a lot of lignin in their cell walls. Lignin makes the cell walls rigid, making the xylem as a whole very rigid so that it will support the plant and keep it upright. Trachia are also involved in conduction, as are cells known as vessel limbs. Vessel limbs are tubular xylem cells designed to force water against the force of gravity so that it can circulate in the upper parts of the plant.
When xylem cells die, they are still useful to the mother plant, unlike dead animal cells, which are often broken down and discarded because they no longer have a function. Although a dead xylem cell is no longer capable of performing complex biological functions, it can still act as part of a support network for the plant because the lignin in the cell walls is intact. These cells can also continue to conduct water through the xylem after death, because their conductive properties are purely mechanical, created by the cell’s shape, rather than being biological in nature.
Without xylem cells, a plant would have no vascular system. Vascular plants are capable of being much more complex than their non-vascular counterparts and can be considered an evolutionary advance of non-vascular plants. Vascular plants can also be called “woody plants” because their xylem gives them a woody texture and the ability to grow large, erect, and complex. Woody plants perform a number of important ecological functions and are also highly prized as ornamentals in gardens around the world.