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.
1. Soredia:
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.
2. Isidia:
Isidia are small, finger-like or conical outgrowths developed on the upper surface of the thallus. Isidia develop into new plants when they detach.