Lichen morphology

Under magnification, a section through a typical foliose lichen thallus reveals four layers of interlaced fungal filaments.

[3] In lichens that include both green algal and cyanobacterial symbionts, the cyanobacteria may be held on the upper or lower surface in small pustules called cephalodia.

The lower cortex of foliose lichens often bears rootlike fungal structures known as rhizines, which serve to attach the thallus to the substrate on which it grows.

Although each lichen thallus generally appears homogeneous, some evidence seems to suggest that the fungal component may consist of more than one genetic individual of that species.

A podetium (plural podetia) is a lichenized stem-like structure of an apothecium rising from the primary body of the thallus.