Question

What is the difference between primary and secondary phloem?

Answer 1

Phloem:

1. Plants rely on two tissues to transport vital nutrients and water: phloem and xylem.
2. The vascular tissue phloem transports carbon (photosynthates) from the leaves to the basal sections of the plant, whereas the undifferentiated tissue vascular cambium is in charge of secondary growth and the repair of injured phloem.
3. Phloem comprises specialised sieve tube cells that aid in nutrient transport throughout the plant.

Difference between primary and secondary phloem:

Primary phloem	Secondary phloem
1. It is made up of the procambium of the apical meristem.	1. A lateral meristem that generates secondary phloem is the vascular cambium.
2. It is found in the main plant body of all vascular plants.	2. Except for annuals, it is only found during secondary growth of dicots and gymnosperms.
3. Every organ contains primary phloem.	3. Secondary phloem is only found in the stems and roots of perennial dicots and gymnosperms.
4. It's on the margins of plant bodies.	4. It grows within the primary phloem.
5. A radial system is not in place.	5. Radial system is traversed by the radial system of phloem rays.
6. Phloem fibres are scarce.	6. Phloem fibres are exclusively present in the plant's peripheral regions.
7. The phloem fibres are more abundant.	7. There are often patches or bands of phloem fibres.
8. The cell types in the main phloem are distributed unevenly.	8. The secondary phloem arrangement is more uniform.
9. There are few sieve tubes in it.	9. It contains more sieve tubes.
10. Sieve tubes are thick and long.	10. Sieve tubes are thicker and shorter in length.
11. There is a scarcity of phloem parenchyma.	11. It contains a lot of phloem parenchyma.