Adrenal Glands

A lichen, rather than being a single entity, is a symbiosis of various species such as fungus and cyanobacteria or algae. Cyanobacteria are commonly referred to as blue-green algae, despite the fact that they are not algae. Chlorophyll is found in photobiont, which is a non-fungal component. 

One photobiont and one mycobiont are common lichen partners, although this is not always the case; some lichens have many photobiont partners. The fungal partner is assumed to be made up of filamentous cells called hyphae. These hyphae can branch, but they maintain a constant distance between them and increase through extension.

Lichen

A few lichens exhibit filamentous formations among photobionts, whereas others are formed up of chains of more or fewer cells. Ascomycetes or Basidiomycetes species are the most common fungus in lichens. The most common algal partners are green algae (Chlorophyta) or blue-green bacteria (Cyanophyceae). 

Although algae may typically thrive on their own in water or damp soil, most fungal partners cannot survive without their phycobiont. Although the largest lichens can produce thallus up to 3 feet long, the most are only a few centimetres long. They have a wide range of colours, from yellow to green to black.

Characteristics of Lichens

Lichens have a number of distinguishing characteristics, some of which are mentioned here for your reference.

• Lichens are a sort of composite thalloid plant that is formed when algae and fungus come together.
• Both use the carbohydrate produced by the algal partner during photosynthesis, while the fungal partner is responsible for water absorption and retention.
• Thalli are characterised as crustose, foliose, or fruticose based on their morphological structure.
• Lichen reproduces in three different ways: vegetative reproduction, asexual reproduction, and sexual reproduction.
• Basidiospores resemble bracket fungus and are produced by Basidiolichen. Near the bottom of the fruit body, basidiospores form.
• Lichen is a slow-growing fungus that can survive in difficult conditions such as high temperatures and dry weather.

Types of Lichens

Lichens can grow in one of the following ways.

• Crustose disperses throughout the substrate.
• Foliose tissue sheets are flat, leaf-like, and loosely attached tissue sheets.
• Squamulose are tightly grouped light flattened pebble units.
• Fruticose are easily accessible upright branching tubes.

Regardless of the differences in fundamental development, lichens have the same interior architecture. The lichen’s layers are defined by the relative density of the fungal partner’s filaments, which make up the majority of the lichen’s body.

The filaments are closely packed together at the outer surface to form a cortex, which helps in environmental interaction.

The algal companion cells are not spread below the cortex because the fungal filaments are dispersed. Underneath the algal layer, which is made up of loosely woven fungal filaments, is the medulla. 

There is another layer under the medulla in foliose lichens, which is in direct contact with the underlying substrate in squamulose and crustose lichens.

Economic Importance of Lichens

Lichens are used for a variety of purposes, including:

• Roccella tinctoria is used to make orchin dye.
• Rochella montagnei is the source of litmus.
• Cladonia rangiferina (Reindeer moss) is a nutritious and antibiotic-rich plant.
• In the perfume industry, Ramalina and Evernia are used.
• Lichens are signs of air pollution.
• Many lichens, such as Usnea and Cladonia, can be used to make medications.
• Lobaria pulmonaria, for example, is used in the tanning of leather.
• Some lichens, such as Usnea, are used in brewing.

Another important function of lichens is that they allow algae to survive in adverse environments where they would otherwise perish. Because the fungus protects its algae, these normally water-dependent animals can thrive in dry, sunny conditions if there are few rain showers or flooding to replenish and store food for the next drought spell.

Because lichens allow algae to live in a wide range of temperatures around the world, they also provide a means for carbon dioxide in the atmosphere to be converted into oxygen, which we all require.

Conclusion 

Lichens are the result of a symbiotic relationship between mycobiont and phycobiont. The algal partner is responsible for photosynthesis, while the fungal partner is responsible for shelter and reproduction. Lichens can reproduce sexually or vegetatively.

They are regarded as an excellent pollution indicator since they grow in the least contaminated areas. Various lichens can be used to make medications. Ecologists can use lichens to better understand the process of biological succession.