Natural History Photographs

Interactions among fungi and bacteria
Lichens with algal and
cyanobacterial symbionts

Some fungi are associated with two symbionts, a green alga and a cyanobacterium. The morphology of the lichen depends very much on the symbiont, which can be seen especially well in Sticta canariensis. The fungus may live together with either the green alga or the cyanobacterium - the result being a completely different morphology. Sometimes you may find composite thalli, in which the green algal morph thallus develops from the cyanobacterial thallus.

Sticta canariensis

green algal photomorph
cyanobacterial photomorph
composite thalli

In contrast to Sticta canariensis, the species shown here below are true tripartite symbioses. In these lichens, the cyanobacterial photobiont is located instructures that clearly stand out from the remaining thallus; such structures are called cephalodia.

Amygdalaria spec.
In the right-most photo, the cephalodia are highlighted.

Nephroma arcticum

Peltigera aphthosa

Placopsis gelida

Placopsis lambdii