support in the plant stem

• Hollow tubes 
• lateral walls (reinforced w/ additional cellulose)
• impregnated w/ lignin 
• pit areas in walls 
• allow lateral movement of water (surrounding cells + tissues)

• Outer cap to vascular bundle 
• by the time fibres have finished growing they are...
• dead
• empty cells
• w/ tapering, interlocking walls 
• ^ thickened by additional layers of cellulose
• impregnated w/ lignin 

Also found between xylem vessels so make whole bundle stronger

support in a herbaceous plant...

1. Turgidity of all cells packing tissue (PARENCHYMA)

2. Turgid w/ vacuoles engorged w/ dilute cell sap

3. rigid (not stretchy) - turgor pressure 

4. all packing cells (tightly) contained in (tough) epidermis  - mechanical support (some protection against parasites eg, funghi) 

• similar to parenchyma 
• have additional layers of cellulose (corners of cells) 
• flexible, supporting cells 
• occurs in leaves + stems 

when hebaceous plants are deprived of water they wilt - showing the importance of turgidity in all living cells supporting the stem and leaves 

• also supported by vascular bundles 
• leaf traces (supply leaves attatched to stem at intervals)