Xylem:
- It is a type of complex tissue present in plants, that primarily transports water & nutrients from roots to stem and the leaves.
- They are responsible for providing mechanical strength to plants.
- Xylem is composed of four different kinds of elements: Tracheids, Vessels, Xylem Fibers, and Xylem Fibers.
Tracheids:
- These are dead, tube-like cells with a tapering end.
- They are present mostly in the gymnosperm and the lower angiosperm.
- They also have a thick lignified wall & lack protoplasm.
- Their main function is the transportation of water and mineral.
Vessels:
- These are long tube-like cylindrical structures.
- The walls are also lignified and usually have a large central cavity. lacking protoplasm.
- They usually have many cells called vessel members that are interconnected by a perforation in common walls.
- They are primarily involved in the conduction of water, and minerals & give mechanical strength to the plant.
Xylem Fibers:
These are dead cells with the lignified walls & a central lumen involved in water transportation and providing mechanical support.
Xylem Parenchyma:
These are living thin-walled cells that help in storing food in form of starch or fat.
On basis of origin, there are two types of xylem cells:
- Primary xylem: It originates from the procambium, further divided into the protoxylem & metaxylem
- Secondary xylem: It originates from the vascular cambium