BASIDIOLICHENS

STUDY OF EXTERNAL FEATURES OF THALLUS (BASIDIOLICHENS)

• The basidiolichens are tropical in distribution and are found growing upon bare soil, rocks and trees.
• There are only three genera of basidiolichens and out of these Cora pavonia is the best known.
• The thallus is much lobed, internally attached to the substratum by rhizines and resembles superfically with ‘bracket fungi’.

STUDY OF INTERNAL STRUCTURE​ OF THALLUS (BASIDIOLICHENS)

• As seen in a vertical cut, the thallus is differentiated into three layers-the superior layer, the algal or gonidial layer and the inferior layer.
• The superior layer is uppermost and consists of loose felt of more or less perpendicular hyphae.
• The algal layer is the middle one. It is made of algal cells (Chroococcus species) intermixed with loose hyphae.
• The inferior layer is the lowermost which is a dense felt of hyphae running in all directions.
• The lowest surface bears concentric outgrowths of more or less perpendicular hyphae.
• Each outgrowth is known as sub-hymenium and its lower face bears a palisade-like layer of basidia.
• Each basidium bears four terminal sterigmata with basidiospores.
• Basidiospores are thus shed from the underside of the lichen. These on contact with alga form a lichen.