What does it mean to impregnate xylem a cell wall?

The walls of xylem cells are lignified (strengthened with a substance called lignin). This allows the xylem to withstand pressure changes as water moves through the plant.

Explanation:

The xylem transports water and minerals from the roots up the plant stem and into the leaves.

In a mature flowering plant or tree, most of the cells that make up the xylem are specialised cells called vessels.

Vessels:

it would be heredity