Lichen
Researchers recently discovered four new lichen species, enhancing biodiversity understanding in the Western Ghats.
Why in News?..Lichen
Lichen is in the news due to recent scientific discoveries and research that highlight its ecological importance.
Key reasons include:
- Discovery of new species: Indian scientists in the Western Ghats have discovered several new species of lichens in 2025, including Allographa effusosoredica, Parmotrema sahyadricum, Solenopsora rhizomorpha, Buelloa ghattensis, and Pyxine janakiae. These discoveries emphasize the rich, yet underdocumented, biodiversity of the region and the need for conservation efforts.
- Role as bioindicators: The new findings reinforce the critical role of lichens as natural bioindicators of air quality and ecosystem health. Their sensitivity to pollutants like sulfur dioxide and heavy metals makes them an effective, low-cost way to monitor environmental changes in both urban and remote areas.
- Ancient ecological significance: A recent study published in November 2025 suggests that ancient lichens (Spongiophyton fossils) were widespread about 410 million years ago, long before complex forests emerged, and played a crucial role in the formation of the Earth's first thin layers of soil. This research provides new insight into the "terrestrialization" of Earth (the shift of life from water to land).
- Astrobiology implications: Research in June 2025 showed that certain desert lichens can survive harsh conditions, including intense UVC radiation, leading scientists to believe they offer evidence for the possibility of life on other planets or exoplanets.
- Conservation and research value: The discoveries highlight the potential for further research into lichens' medicinal properties (some have antifungal and anti-cancer properties) and their role in carbon and nitrogen cycles, underscoring the value of protecting their habitats.
About Lichen
Lichens are unique composite organisms that result from a mutualistic symbiotic association between a fungus (the mycobiont) and a photosynthetic partner (the photobiont), typically a green alga or cyanobacterium. This partnership allows them to survive in diverse and often extreme environments where neither component could thrive alone.
Structure and Components
The body of a lichen is called a thallus, which has a form and structure distinct from its individual components.
- Fungal Partner (Mycobiont): The dominant partner, typically an ascomycete or basidiomycete fungus, forms the structural framework. It provides shelter and protection from harsh conditions like UV radiation and desiccation, and absorbs water and mineral nutrients from the atmosphere, rain, and substrate.
- Photosynthetic Partner (Photobiont): This component, usually green algae or cyanobacteria, contains chlorophyll and produces carbohydrates (food) for both organisms through photosynthesis. If the partner is a cyanobacterium, it can also fix atmospheric nitrogen, providing essential nutrients to the ecosystem.
- Internal Layers: The thallus is often stratified into distinct layers, including an outer protective cortex, a layer containing the photobiont cells, and a loosely packed inner medulla of fungal filaments.
Types of Lichens
Lichens are categorized mainly by their growth form or morphology:
- Crustose: These form a thin crust tightly attached to surfaces.
- Foliose: These are leaf-like lichens with distinct upper and lower sides, anchored by rhizines.
- Fruticose: These are branched or shrub-like, attached at a single point and growing upright or hanging.
- Other types include squamulose, leprose, and gelatinous forms.
Reproduction
Lichens reproduce both vegetatively and sexually. Vegetative reproduction, the more common method, uses structures like soredia and isidia for dispersal of both partners. Sexual reproduction occurs only in the fungal partner, which produces spores that must find a compatible photobiont to form a new lichen.
Ecological Importance and Human Uses
Lichens are significant in ecosystems, often being the first organisms to colonize bare ground and contributing to soil formation. They serve as bioindicators of air quality due to their sensitivity to pollutants. Lichens are also a food source for animals like reindeer and caribou, and have been used by humans for dyes, medicine, and perfumes.
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