Differentiate between:

(i) Xylem and phloem.

(ii) Vessel and sieve tube.

(iii) Tracheid and vessel.

Xylem

Phloem

1. It consists mainly the dead tissue (except xylem parenchyma).

1. It mostly has living tissue (except phloem fibre).

2. It is composed of tracheids, vessels, xylem parenchyma and xylem fibre, (in stems)

2. It is composed of sieve tube, sieve plates, companion cell, phloem parenchyma and phloem fibre.

3. It transports water and mineral from roots to other parts of the plant.

3. It transports prepared food from leaves to the other plant parts.

4. The flow is unidirectional.

4. Flow is bi-directional. 

Vessel

Sieve Tube

1. It is a part of Xylem tissue

1 It is a part of phloem tissue. 

2. It is a long distance channel made up of a number of dead cells with hollow lumen.

2. It is a long distance channel made up of a number of living cells with vacuolated cytoplasm.

3. Vessel conducts water and mineral salts.

3. Sieve tube conducts food or organic nutrients.

3. The wall is lignified.

3. The wall is unlignified.

4. The wall is thick.

4. The wall is thin.

5. The end walls are commonly dissolved completely.

5. The end walls are perforated to form sieves plate.

6. Besides conduction of sap, a vessel provides mechanical strength.

6. It does not provide any mechanical strength.

Vessel

Tracheid

1. A vessel consists of a large number of cells fused together in a single file.

1. A tracheid consists of a single cell.

2. The ends are rounded.

2. The ends are pointed.

3. The septa between adjacent cells of a vessel are usually absent.

3. The walls between adjacent tracheids, remain intact.

4. The vessel is quite long (1-6 metres).

4. The tracheid is comparatively short (generally 1 mm).

5. The wall is less thickened.

5. The wall is more thickened.

6. The lumen is wide.

6. The lumen is narrow.