What is the difference between Primary and Secondary Xylem?

Primary Xylem:

1. It is primary in nature and is derived from procambium.

2. It is differentiated into protoxylem and metaxylem.

3. Tacheids and vessels are narrow and long vessels do not possess tylosis.

4. Xylem fibres are less in number.

5. No differentiation of sapwood and heartwood and no formation of annual ring.

Secondary Xylem:

1. It is secondary in nature and is derived from fascicular and interfascicular cambium.

2. No such differentiation is seen.

3. These are wide and short. Vessels are blocked by tyloses.

4. These are abundantly present.

5. Sapwood and heartwood are distinct annual ring formation occurs.