Xylem

• Tissue is made of: xylem vessels, xylem tracheids, and xylem parenchyma; function: transport water and dissolved ions from root to stem and all around the plants in one direction only and give mechanical support to plant organs
• Elongated and join end to end to form a column of cells; end walls between them break down forming a tube of hollow dead cells (with wide lumen) for the transport of water and mineral ions
• Cellulose walls become impregnated by lignin; impermeable to respiratory gases and water, so cells’ living content dies; some area lignification is incomplete leaving gaps called ‘bordered pits’
• Tracheid fibres in the xylem are individual dead cells that have lignified walls - for structural support only and Parenchyma cells are the only living cells in xylem tissue; storing starch and providing metabolic support for other cells during differentiation
• Xylem Adaptations

  A) lumen

  B) water

  C) water

  D) less

  E) broken

  F) continuous

  G) cohesion

  H) strengthens

  I) thickens

  J) collapse

  K) tension

  L) adhesion

  M) capillarity

  N) spiral

  O) annular

  P) reticulate

  Q) strech

  R) flexibility

  S) wide lumen

  T) pits

  U) cellulose

  V) lignin

  W) blockage

  X) supply