Lichens are slow growing, long living organism formed by the symbiotic association between algae and fungi that form a unique morphology distinct from both partner.
•The fungal partner is called mycobiont
•The algal partner is called phycobiont
Vegetative reproduction in lichen occurs by fragmentation isidia and soredia.
Soredia are minute, rounded, powdery vegetative reproductive bodies in lichen formed on the thallus surface in pustule like areas called soralia.
•Each soredium consists of few algal cells surrounded by fungal hyphae.
Soredia detaches from the thallus and are carried away by wind. On falling on suitable substrata, it germinates and give rise to new thallus
Isidia are stalked, branched or unbranched, pappilate outgrowths formed on the thallus surface.
It consists of algal cells and fungal hyphae covered by definite cortex. Sometimes this detaches from the parent plant and give rise to new thallus
•If it remains in the parent thallus, it will increase the photosynthetic efficiency by increasing the surface area for photosynthesis