Xylem

There are 4 types of xylem tissues:

~tracheid

~Xylem vessel

~xylem fibre

~xylem parenchyma



The main function of xylem tissues is for the transport of water and mineral and for support.



TRANSPORT & SUPPORT:

Tracheid: The tracheids are elongated, dead cells, with tapering ends.It is strengthened with the lignified secondary cell wall. The tapering ends overlap and interlock with each other ,increasing its strength.They have pits to connect to lumens of other cells.This allows water to move from one tracheid to another and to the surrounding cells.tracheids are the main water conducting ducts in ferns and conifer.Tracheids:

Xylem vessel :They are only found in angiosperms.They are cylindrical dead cells in which most water travels.Thus,it has no cytoplasmic content and no protoplasm.They have a bigger diameter than tracheids.The end walls of then vessels are perforated with large pores or completely disintegrated to allow continuous flow of water.The deposition of lignin in the secondary wall is not always uniform. As a result, the xylem vessels exhibit different types of secondary thickenings. On this basis, xylem vessels can be distinguished into five types.
~Annular
~spiral
~scalariform
~reticulate
~pitted

SUPPORT ONLY:
Xylem fibres : they are dead cells with lignified cell walls.they support the plant tissues.

PACKING TISSUES :
Xylem parenchyma : They are the only living xylem tissue. they are used to store food.