Xylem of the vascular conducting tissues is formed of lignified and sclarified dead cells. The cells of xylem need to conduct a large amount of water and therefore need to be hollow. Due to this the organelles are absent and the cells are hollow, also the ends of the cells do not have a cell wall and the cells are continuous. This is needed for the continuous transport of substances. For this, the xylem cells cannot be living and are dead.