Question

Lichens growing on rocks are called
(a) Saxicolous
(b) Corticolous
(c) Lignicolous
(d) Terricolous

Answer 1

Hint: That symbiotic relationship of algae and fungi which can be found in extreme habitats such as hot and cold climates and are grown in almost all the places like rocks, bark, soil, wood, etc, and are named accordingly. The Latin name for the rock or stone is “sax”

Complete answer:
The process in which the two organisms that live in a close relationship physically and they both help each other i.e mutually benefited. This phenomenon is called symbiosis and the organisms are called symbionts. Liches are plant-like organisms but not plants that are formed from the fungi especially cyanobacteria and live in association with filaments of species of fungi. They grow in different habitats. Saxicolous are the lichens that grow on rocks, corticolous are the lichens that grow on bark, lignicolous are the lichens that grow on wood, and terricolous are the lichens that grow on soil.

Additional information:
- Lichens appear in many environmental conditions and can be grown in extreme conditions like arctic tundra regions and hot climates of deserts, they can be found below the sea level or high altitude regions.
- They are abundantly grown on plant barks and areas with more moisture content. They can also be grown on rocks, soil, bones, walls, etc
- Lichens cover about 6-8% of the earth’s surface and are about 20000 species found on the earth.
- Lichens that grow on rocks, bark, wood, and soil are called saxicolous, corticolous, lignicolous, terricolous respectively.
So, the correct answer is ‘(a) Saxicolous’

Note:
- In many parts of the world, lichens are consumed by humans as food but the two limitations found are their polysaccharides cannot be digestible and their secondary toxins are removed before eating.
- Lichens are also used in traditional medicine and research.