Question

Periderm includes
A. Cork cambium (phellogen), cork (phellem) and secondary cortex (phelloderm)
B. Cork cambium and cork
C. Cork
D. Cork and secondary phloem

Answer 1

The periderm replaces the epidermis during growth in thickness of stems which is the secondary protective (dermal) tissue and roots of gymnosperms and dicotyledons (i.e., secondary growth).

Complete Answer:
Let’s discuss the question and find the correct answer.
- Cork cambium (phellogen), cork (phellem) and secondary cortex (phelloderm): The periderm constitutes the cork, phelloderm or secondary and cork cambium or phellogen cortex which is a multilayered tissue system.
- Cork cambium and cork: The cork cambium originates from the secondary lateral meristem while the vascular cambium originates from the apical meristem. The bark and the secondary cortex has been given rise by the cambium.
- Cork: The walls of cork cells contain a chemical called suberin, which makes them impermeable to water and gases. Water loss from plants has been prevented by the cork cells and also makes them more resistant to bacterial and fungal infection.
- Cork and secondary phloem: The sieve-tube members, companion cells, scattered parenchyma, ray parenchyma, and fibres have been consisted by the secondary phloem of angiosperms. Alternating with bands of sieve tubes and parenchyma cells the fibres occur in clusters or as bands.

Hence, the option A: Cork cambium (phellogen), cork (phellem) and secondary cortex (phelloderm) is the correct answer.

Note: The periderm is a multilayered tissue system unlike typical epidermis, the bulk of which usually constitutes the cork, or phellem, cork cambium or phellogen and phelloderm or secondary cortex.