{{Short description, Morphological structure found in some lichens
Cephalodia (singular cephalodium) are small gall-like structures found in some species of lichens that contain cyanobacterial symbionts. Cephalodia can occur within the tissues of the lichen, or on its upper or lower surface. Lichens that have both
green algal
The green algae (singular: green alga) are a group consisting of the Prasinodermophyta and its unnamed sister which contains the Chlorophyta and Charophyta/Streptophyta. The land plants (Embryophytes) have emerged deep in the Charophyte alga as ...
and cyanobacterial symbionts restrict the cyanobacteria to cephalodia. Lichens that have only cyanobacterial symbionts do not have cephalodia: instead the cyanobacteria are widely distributed throughout the lichen. Lichens with cephalodia can fix nitrogen, and can be an important contributor of nitrogen to the ecosystem.
References
*Brodo, I. M., S. D. Sharnoff, and S. Sharnoff. 2001. Lichens of North America. Yale University Press: New Haven.
LichensFungal morphology and anatomy