Introduction

Cork cambium is the layer of cambium that is usually seen in woody plants. Different types of tissues and cells form the plant body, which helps the plant to grow by producing new cells and tissues. Cork cambium is a type of secondary meristematic tissue.

The Secondary tissues are formed during the secondary growth which results in pressure being applied on the epidermis of the stems and roots and eventually, they rupture. After the death of epidermal cells and extracellular tissue, a new protective secondary tissue layer is formed. This is periderm. The periderm consists of three regions. Cork cambium is one of them (2) & (4).

Definition of cork cambium

It is a secondary meristem arising from the living permanent cells which have the capacity to divide. The stem of a woody plant has a layer of cambium that produces cork on the outside and phelloderm on the inner side is called cork cambium. It is also called phellogen.

When sufficient pressure is created from the inner part of the tissues and the epidermis ruptures, this cambium is formed in the surface layers of the cortex. It forms the bark of woody plants (1).

Characteristics of cork cambium

1. Involved in secondary growth.

2. This tissue produces the cork and the secondary cortex.

3. Cork cambium cuts more phellem or cork cells on the outer side than phelloderm on the inner side.

4. The growth and development of this tissue are very variable between different types of species.

5. This cambium originates from the secondary lateral meristem.

6. It is a type of tissue found in many vascular plants as part of the epidermis.

7. This tissue is also derived from pericycle cells of roots.

8. In dicot roots, this tissue originated from the cortex.

9. It is the meristematic cell layer that is responsible for the development of the periderm.

10. This secondary meristematic tissue is composed of parenchyma and collenchyma cells. So it is capable of division (3).

The function of cork cambium

1. The primary function of the tissue is to protect the plant’s body against physical damage.

2. It provides new dermal tissues which eventually replace the epidermis-formed protoderm.

3. This tissue also helps reduce water loss.

4. Periderm is produced by this cambium. The cork cambium, cork cells, and phelloderm combine to form the periderm.

5. It produces cork or phellem towards the outer side and secondary cortex towards the inner side.

6. This tissue plays a primary role in increasing the density of the stems of woody plants.

7. It makes cork cells that contain a waxy substance called suberin (1) & (4).

Definition of Vascular cambium

The vascular cambium is a lateral meristematic tissue. It is a vascular tissue of plants. A cylindrical layer of meristematic tissue that is found between the primary xylem and primary phloem is called vascular cambium. Main cambium, wood cambium or bifacial cambium are the common names of vascular cambium. Only dicot plants have vascular cambium, monocots do not have vascular cambium (5).

Characteristics of vascular cambium

1. It is located between the primary xylem and phloem of the plant’s young stem and root.

2. This tissue is a lateral meristem that forms a secondary xylem on the inside and a secondary phloem on the outside.

3. Vascular cambium is the main growth tissue in the stem and roots of plants.

4. This type of cambium is present in woody plants and most dicots plants.

5. Vascular cambium forms the phloem.

6. Apical meristem is the origin for vascular cambium.

7. Vascular cambium activity is seasonally affected. In summer, vascular cambium forms wide xylem vessels to conduct more water to the leaves of the plant as the rate of photosynthesis is higher in summer. In winter, the rate of photosynthesis is low, so the vascular cambium produces small xylem vessels.

8. The vascular cambium is single-layer cells (2) & (3).

The function of vascular cambium

1. The vascular cambium produces secondary xylem and secondary phloem.

2. It provides structural support to the plant.

3. This tissue produces vascular tissue to help the internal flow of plants.

4. It also helps in the growth of roots and shoots.

5. Wood is formed from a secondary xylem produced by the vascular cambium.

6. The main function of this tissue is to form xylem and phloem cells.

7. Increased diameter of plant stems and roots is caused by vascular cambium (4).

Difference between Vascular cambium and cork cambium

There are two types of tissue present in dicot plants known as cork cambium and vascular cambium. Both tissues are plant tissues but some differences are observed between them.

Content	Vascular cambium	Cork cambium
1. Definition	Vascular cambium is a plant tissue located between the primary xylem and the primary phloem.	Cork cambium is the lateral meristematic tissue that produces cork on the outside and phelloderm on the inner side.
2. Location	It is located between the primary xylem and the primary phloem.	This tissue is located outside the vascular tissue.
3. Produce	This type of cambium produces secondary xylem and secondary phloem.	This tissue produces both cork cells and the secondary cortex.
4. Shape	The shape of this tissue is spindle or cuboidal.	Its shape is rectangular or polygonal.
5. Evolved from	The vascular cambium evolved from the apical meristem.	This tissue evolved from the secondary lateral meristem tissue.
6. Presence of lenticels	It does not produce lenticels.	Cork cambium contains lenticels because this tissue produces lenticels.
7. Medullary ray	This tissue generates a medullary ray.	It does not produce a medullary ray.
8. Substances	The vascular cambium did not produce fatty substances.	The cambium produces fatty substances (suberin).
9. Cell arranging	Non-stratified type.	Stratified types.
10. Importance	The primary role of this tissue is to produce vascular tissue to support the internal flow of the plant and to provide structural support to the plant.	It protects the plant from external damage. These tissues also play an important role in preventing water damage (2) & (5).

Similarities

In addition to the above differences, some similarities exist between these two tissues. Such as-

• Cork cambium and vascular cambium both tissue are both generated from meristematic tissue.
• These two tissues help in the secondary growth of the stem and root of dicot plants. They increase the diameter of the stem and roots.
• Both tissues are actively capable of division.
• Vascular cambium and cork cambium are found in tubular rings.
• These two types of secondary meristematic tissue in plants produce a type of cell that provides protection and structural support to the dicot plant (3).

Q&A

1. Cork cambium is the protective tissue of a stem. What mechanism does it use to protect the stem?

• The water deposition in the cork cambium acts as a barrier and protects the stem from physical damage.
• Accumulation of minerals in this lateral meristematic tissue acts as a barrier and protects the stem from physical damage and water loss.
• Deposits of wax and oils in this cambium act as an obstruction and maintain the stem from physical damage and water loss.

2. What is cork cambium?

The stem or roots of a woody plant have a layer of cambium that produces cork on the outside and the phelloderm on the inner side is called cork cambium.

3. What is the Function of cork cambium?

• The main function of this tissue is to protect the plant’s body against physical damage.
• It also helps reduce water loss.
• Cork cambium makes cork cells that contain a waxy substance called suberin.
• This tissue plays a primary role in increasing the density of the stems of woody plants.

4. What does cork cambium produce?

It produces cork cells in its outside part and the secondary cortex or phelloderm to its inside part. The secondary cortex or phelloderm is a layer of parenchyma. Periderm is produced by cork cambium. Cork cambium also produces new dermal tissue. The new dermal tissue eventually replaces the epidermis formed by the protoderm.

5. What is cork cambium?

Cork cambium is a lateral meristematic tissue on the outside of the vascular tissue. This tissue is the layer of bark between the primary phloem and cork cells. Cork cambium is rather simple in comparison to the cambium. It has only one type of initial cell.

Reference

1. B Agarwal and V. K. Agarwal. Unified Botany, B.Sc. second Year. Shiva Lal Agarwal & Company Publications, Indore. Chapter: Vascular cambium and its functions. Page no- 78 to 80. & chapter: secondary phloem, cork cambium, and periderm. Page no: 90 to 97.