Asexual reproduction in lichens takes place by the formation of soredia and isidia which is possessed by both the algal and fungal partners of the thallus.
The more organized soredia occurring on localized area are called soralia. These are pustule-like and are seen as small white areas.
Soredia are asexual “reproductive bodies” found in lichens. They are knots of hyphae containing a few algal cells. They are small granule-like or bud-like outgrowths on the upper surface of the thallus. Each soridium is formed of one to a few algal cells surrounded by closely arranged fungal hyphae produced by branching of a hypha from the algal region.
Isidia are small, finger-like or conical outgrowths developed on the upper surface of the thallus. Isidia develop into new plants when they detach.