General Structure and Classification of lichens based on morphology of the Lichen Thallus


The word lichen is gotten from a Greek word (Gr leikhēn = to lick). In Latin līchēn, implies a sort of plant. These are exceptional living beings from multiple points of view. Lichens speak to a cozy and long haul advantageous interaction of green growth and parasites. The growth accomplice is called mycobiont and a photosynthetic algal accomplice, the photobiont (prior known as phycobiont). A steady thallus with a particular morphology is framed when (at least two) accomplices meet up, prompting a drawn out advantageous relationship. However, generally, in numerous lichens, this affiliation separates, with the accomplices restoring the relationship from the independently scattered parasitic spores and photosynthetic cells. 

General Structure 

The contagious accomplice as a rule offers more to the construction and the algal accomplice produces nourishment for the lichen by photosynthesis. As the outside surface is framed by parasitic accomplice it is knowns as the exhibiting, while, the unicellular or filamentous photobiont cells are named as occupants as situated inside the lichen thallus. 

Lichenicolous growths These are framed when an organism harps on or in lichens as parasites (microbes), commensals or saprobes. These are otherwise called lichen-possessing organisms. So it speaks to relationship of two parasites with a solitary photobiont. There are around 300 genera and 1000 types of obligately lichenicolous parasites currently known. 

These are known to 

Induce nerves on the thallus (for example Polycoccum galligenum), 

Occur as saprophytes on dead or rotting lichen thalli (for example Niesslia cladoniicola), 

Occur as parasites causing necrotic patches (for example Lichenoconium lecanarae) executing portions of thalli. 

Para symbiosis-It is a steady circumstance of Lichenivorous growths wherein the host lichen is absolutely unaffected from outward appearances, along these lines speaking to harmonious relationship with a generally existing beneficial interaction for example Arrhinia glaucomaria on Lecanora rupicola. 

Advancement of mole like designs named cephaloid (sing. cephalodium. Gr. kephale = head) happens when a solitary mycobiont structures a relationship with two or seldom three distinctive photobionts. These outgrowths structure basic piece of the lichen. 

Construction of Heteroamorous Lichens' Thallus 

The vertical part of foliose lichen which is a commonplace illustration of heteroamorous type, the accompanying layers might be recognized start to finish. 

Upper Cortex. Typically made out of firmly intertwined mycelium, that gives it a phone appearance. This cell appearance is alluded to as pseudoparenchymatous. 

Algal Layer. Made out of interlaced hyphae with the algal cells. This is the ideal area for the algal cells beneath the upper cortex where it gets the ideal measure of sunlight based radiation, for photosynthesis, yet not immediate sun based radiation which would be destructive. 

Medullary Layer or medulla. Made out of freely interlaced mycelium. This layer is altogether contagious. 

Lower Cortex. Generally same arrangement as the upper cortex and joined to the foundation by exceptional connection organs as clarified before. These designs are completely parasitic in beginning, and serve to moor the thallus to the foundation. 

Development of Lichen Thalli 

In spite of the fact that lichens need roots, they are generally immovably joined to the foundations by different sorts of connection structures clarified previously. Lichens develop amazingly gradually; with a couple of millimeters increment their length or breadth every year. In the event of the quickest developing assortments not in excess of 30 mm are added to their length every year.

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