Phellem – Definition & Detailed Explanation – Botanical Terms Glossary

What is Phellem?

Phellem, also known as cork tissue, is a specialized type of tissue found in the outer bark of woody plants. It is a protective layer that covers the stems, branches, and roots of plants, providing a barrier against physical damage, pathogens, and environmental stresses. Phellem is derived from the cork cambium, a layer of meristematic tissue that produces cork cells. These cells undergo a series of changes, including suberization, to form the impermeable and protective layer known as phellem.

What is the function of Phellem in plants?

The primary function of phellem in plants is to provide protection against external threats. It serves as a physical barrier that prevents the entry of pathogens, such as bacteria and fungi, into the plant tissues. Phellem also helps reduce water loss through transpiration and protects the plant from mechanical damage, such as abrasion and herbivory. Additionally, phellem plays a role in regulating gas exchange and temperature control in plants.

What are the characteristics of Phellem?

Phellem is characterized by its thick-walled cells that are impregnated with suberin, a waxy and hydrophobic substance. This suberized layer makes phellem impermeable to water and gases, creating a protective barrier for the plant. Phellem cells are dead at maturity, lacking protoplasts and other living components. The cells are arranged in layers, forming a continuous and durable outer covering for the plant.

How does Phellem protect plants?

Phellem protects plants by forming a physical barrier that prevents the entry of pathogens, such as bacteria, fungi, and viruses. The impermeable nature of phellem also helps reduce water loss through transpiration, conserving the plant’s internal water supply. Additionally, phellem provides protection against mechanical damage, such as abrasion from environmental factors or herbivory from animals. By regulating gas exchange and temperature control, phellem helps maintain the optimal conditions for plant growth and development.

What is the difference between Phellem and other plant tissues?

Phellem differs from other plant tissues, such as phloem and xylem, in its structure and function. Unlike phloem and xylem, which are involved in the transport of nutrients and water within the plant, phellem serves primarily as a protective layer. Phellem is composed of dead cells that lack protoplasts, while phloem and xylem contain living cells that are actively involved in nutrient transport. Additionally, phellem is characterized by its suberized cell walls, which make it impermeable to water and gases, unlike the more permeable cell walls of phloem and xylem.

How is Phellem important in plant survival?

Phellem is essential for plant survival as it provides protection against a wide range of external threats. By forming a physical barrier that prevents the entry of pathogens and reduces water loss, phellem helps maintain the health and integrity of the plant. Without phellem, plants would be more susceptible to infections, dehydration, and mechanical damage, which could compromise their ability to grow and reproduce. Overall, phellem plays a crucial role in ensuring the survival and success of woody plants in diverse environments.