Table of Contents
Introduction to Lichen
Lichen – Introduction: Lichens are composite organisms consisting of a fungus and an alga. The fungus is the dominant partner and provides the structure, while the alga provides the photosynthetic component. Lichens are found in a variety of habitats, from deserts to rain forests, and can be a dominant form of vegetation in some ecosystems.
Classification of Lichen
Lichens are a symbiotic association of a fungus and an alga. The fungus provides a protective sheath and water absorption while the alga photosynthesizes and produces food for the lichen. Lichens are classified according to their morphology and the fungus they contain. There are three main types of lichens: crustose, foliose, and fruticose. Crustose lichens are thin, flat, and tightly attached to the surface on which they grow. Folios lichens are leaf-like in appearance and are attached to the surface by a short stalk. Fruticose lichens are shrub-like in appearance and are attached to the surface by a long stalk.
Lichens can also be classified according to the type of fungus they contain. The most common types of fungus are as follows:
- Ascomycetes: This type of fungus contains sac-like cells called asci. Ascomycetes are the most common type of fungus found in lichens.
- Basidiomycetes: This type of fungus contains club-shaped cells called basidiospores. Basidiomycetes are common in lichens that grow in areas that are exposed to the air.
- Lichenized Glomeromycetes: This type of fungus is found only in lichens and is not found in any other environment. Glomeromycetes are a type of fungi that form a mutualistic relationship with the alga in lichens.
A. Based on their Growth
- Lichens are a symbiotic organism consisting of a fungus and an alga. The fungus provides the structure of the lichen while the alga provides the photosynthetic component. Lichens are classified based on their growth form.
- Foliose lichens are those that grow in the form of a leaf. Crustose lichens are those that grow in a crust-like form. Fruticose lichens are those that grow in the form of a shrub. Squamulose lichens are those that grow in the form of a scale.
- Lichens are also classified based on their color. Green lichens are those that have a green alga. Brown lichens are those that have a brown alga. Black lichens are those that have a black fungus.
- Lichens are an important part of the ecosystem. They provide food and shelter for animals and they stabilize the soil.
B. Based on their Habitat
Lichens are a composite organism consisting of a fungal partner and an alga or cyanobacterium. The fungus provides physical structure, while the alga or cyanobacterium photosynthesize to provide nutrients to the lichen. Lichens occur in a variety of habitats, including on tree bark, rocks, and in soils.
There are three main types of lichens, which are based on their habitat:
- Terrestrial lichens: These lichens grow on land, typically on rocks, trees, or in soils.
- Epiphytic lichens: These lichens grow on other plants, such as trees or shrubs. They typically use the host plant for physical support, but do not harm the plant.
- Aquatic lichens: These lichens grow in water, typically in salt or fresh water.
C. Based on their Internal Structure
- Organelles are organ-like structures inside of cells. They have specific functions that allow the cell to carry out its duties. There are three types of organelles: endoplasmic reticulum, Golgi apparatus, and mitochondria.
- The endoplasmic reticulum is a network of tubes that helps the cell process and package proteins. The Golgi apparatus is responsible for sorting and shipping proteins and other materials to the correct part of the cell. Mitochondria generate energy for the cell.
D. On the Basis of their Fungal Partner
Lichens are composite organisms that are formed from an alga and a fungus. The fungus provides the structure of the lichen while the alga provides the photosynthetic component. The two organisms are intimately associated and cannot live without each other.
Important Role of Lichens
Lichens are a symbiotic association of a fungus and an alga. The fungus is the dominant partner and provides the lichen with structure and water. The alga is the photosynthetic partner and provides the lichen with food. Lichens are important in the environment because they can grow on bare rock and form a biological crust that stabilizes the surface. They also provide food and shelter for animals.
