What is the meaning of xylem lumen?
Xylem lumen may be defined as the inner open space or a central hollow cavity present inside the xylem. It serves as the passage for the water and minerals to flow through it.
Balloon like expansions of xylem parenchyma into the lumen of the vessels in secondary xylem are called
Tracheae or xylem vessels are long tube-like structures that are formed by cells stacked like coins. How is the presence of inner lumen explained here?