Protective tissues prevent desiccation (loss of water from plant body), infection, and mechanical injury.Helps in preventing the entry of pathogens.Cork, which is a protective tissue, is light and does not catch fire easily.So,they are used as insulators,shock absorbers,linoleum (in flooring),sports goods (shuttle cocks,cricket balls,wooden paddles in table tennis,etc.).Cork can also be used commercially.

Protective Tissues in Plants

There are several protective tissues in plants that play a crucial role in safeguarding the plant from external factors. Two of the main protective tissues are epidermis and cork.

Epidermis:
The epidermis is the outermost layer of cells that covers the entire plant body, including the leaves, stems, and roots. It acts as a protective barrier between the plant and its surroundings. The epidermis consists of tightly packed cells that form a continuous layer.

Functions of Epidermis:
1. Protection: The primary function of the epidermis is to protect the underlying tissues from physical damage, such as mechanical stress, UV radiation, and excessive water loss. The outermost layer of the epidermis, called the cuticle, is made up of waxy substances that provide a waterproof barrier, preventing excessive transpiration and reducing the risk of desiccation.

2. Prevention of Pathogen Invasion: The epidermis acts as the first line of defense against pathogen invasion. It secretes various chemical compounds, including antimicrobial substances, to inhibit the growth of pathogens and prevent infections.

3. Gas Exchange: The epidermis contains small openings called stomata, which facilitate gas exchange. Stomata are surrounded by specialized cells known as guard cells that control their opening and closing. This allows the plant to regulate the exchange of gases, such as carbon dioxide and oxygen, for photosynthesis and respiration.

4. Root Hair Formation: In roots, the epidermis also plays a role in the absorption of water and nutrients. It possesses root hairs, which are extensions of individual epidermal cells that increase the surface area for enhanced absorption.

Cork:
Cork is a protective tissue found in the bark of woody plants, such as trees. It is a secondary tissue that replaces the epidermis in older stems and roots. Cork cells are dead at maturity and are characterized by their thick, waterproof cell walls containing a substance called suberin.

Functions of Cork:
1. Protection: Cork provides mechanical protection to the underlying tissues, preventing damage from physical abrasion, herbivory, and extreme climatic conditions.

2. Waterproofing: The presence of suberin in the cork cell walls makes them impermeable to water and gases. This helps reduce water loss through the bark and prevents the entry of pathogens and toxins.

3. Insulation: Cork acts as an excellent insulator, protecting the plant from temperature extremes. Its low thermal conductivity helps regulate internal plant temperature and prevents heat loss.

4. Gas Exchange: Despite its waterproof nature, cork allows a limited amount of gas exchange through specialized structures called lenticels. These small pores in the cork layer permit the exchange of gases between the internal tissues and the outside environment.

In conclusion, the epidermis and cork are two essential protective tissues in plants. The epidermis acts as a physical barrier, regulates gas exchange, prevents water loss, and defends against pathogens. On the other hand, cork provides protection, waterproofing, insulation, and limited gas exchange. Together, these tissues contribute to the overall health and survival of plants in diverse environmental conditions.