Lichenology: Progress and Problems

Chimeroid Associations in the Genus Peltigera

“…We agree with Culberson (1977) that the identity of the mycobiont in the bluegreen and green parts of chimeroid associations cannot be proven by observations of the type presented here; only controlled laboratory experiments with isolates of mycobionts and appropriate phycobionts can determine the actual situation. The evidence presented supports a hypothesis that, at least in some populations of Peltigera aphthosa, a single fungus is capable of producing distinct lichen thalli by different morphogenic responses to different phycobionts.…”

“…The biological implications of the phenomenon, however, are only now becoming fully appreciated. If one species of fungus can indeed form two morphologically distinguishable lichens with different phycobionts, 'the principal lichenological axiom and article of faith that every different lichen differs because it is the product of a different fungal species', as stated by Culberson (1977), is brought into question. However inconvenient it may be for lichenologists to accept the possibility that this axiom is overstated, it is clear that new evidence is surfacing which necessitates its re-examination.…”