Question

The cambium which produces cork is called as
A. Phelloderm
B. Phellogen
C. Periblem
D. Plerome

Answer 1

A plant undergoes two types of growth i.e. primary growth and secondary growth. The primary growth includes the increase in the length of the stem and root whereas the increase in thickness or girth of a plant is considered as secondary growth.

Complete answer:
The secondary or lateral meristem helps in the secondary growth of the plant. Secondary meristem includes fascicular vascular cambium, interfascicular cambium, and cork cambium. They produce secondary tissues. The secondary tissues are protective and are present in the outermost layer of the body thus called external protective tissues, such as in stems, roots, and leaves. They protect the body from infections, dehydration, injuries, etc.
When the plant undergoes secondary growth, its girth increases due to the vascular cambium, and thus its outer cortical and epidermal layer breaks down. To replace these layers, another meristematic tissue called cork cambium starts developing in the cortex region. Cork cambium is also known as Phellogen.

Thus the cambium that produces cork is Phellogen. The correct option is (B) Phellogen.

Additional information: Phellogen is the meristematic tissue responsible for the secondary growth in plants. It is made up of thin-walled rectangular cells having few layers. Phellogen forms cork or phellem on its outer side, while the secondary cortex or phelloderm on the inner side. Phellogen along with phellem and phelloderm consists of the periderm. Cork has a deposition of suberin in their cell wall which makes it impervious to water.

Note:
Primary growth occurs in all plants but secondary growth occurs only in special type of plants. The plants that do not show secondary growth are monocotyledons. Secondary growth occurs in plants in which a cambium is present between the xylem and phloem and such plants are mostly dicotyledons.