Xylem

• xylem

  = transports water and mineral ions and support the cell.
• adaptations:

  -made from dead cells aligned end to end to form a continuous column

  -tubes are narrow so water column don't break easily

  -lignin deposits in walls allow xylem to grow and stops it collapsing.

  -bordered pits allow water to move sideways from one vessel to another.
• uni-lateral movement

  -long hollow, made of several columns of cells fusing together

  -thick walled parenchyma packs around xylem vessels, storing food and containing tannin deposits.

  -xylem fibres are long cells with lignified secondary walls that provide extra mechanical strength.

  -lignin can form rings, spirals or solid tubes with lots small unlignified areas called bordered pits= where water leaves the xylem to other areas.