Features of xylem and phloem vessels

Describe the features of a phloem vessel

• Companion cell is attached to to the sieve tube element by the plasmodesmata, it does all the processes of living cells for sieve cells and is very metabolically active

• Contain parenchyma which are packing tissues keeping all phloem elements in place

• Phloem fibres for support

• Few organelles in the sieve tube element, only a cytoplasm

Describe the features of a xylem vessel

• Dead, making it easy for water to flow

• Walls are strengthened with lignin which is waterproof, killing cells and is deposited as rings

• Gaps in lignin called pits allow water to leave the tubes (lateral movement of water)

• Lignin also provides mechanical strength preventing xylem collapse, and allowing the adhesion of water

• Parenchyma are packing tissues

• Xylem fibres for support

• Vessels are wider

• Tracheids are narrower

What is the direction of movement in xylem?

One way

What is the direction of travel in the phloem?

Bi-directional, up and down