Wednesday, April 21, 2010

Lichen Photomorphs in Costa Rica

Last year I traveled to Costa Rica in search of lichens. One of the most exciting lichenological phenomena that I observed was the presence of 'photomorphs' in the lichen-forming fungal genus Sticta. Photomorphs (a.k.a., photosymbiodemes) are created when the same fungus associates with two entirely different photobionts (most noticeable when one photobiont is a green alga and the other is a cyanobacterium). I observed this in several species of Sticta while in Costa Rica. This photo shows one example, where the bright green lobes are associated with a green alga and the darker brown lobes are associated with a cyanobacterium:
Some other nice photos from my trip include a moth disguising itself as a lichen...
...and a rainbow over some lichen-covered fence posts by the side of the highway near Cerro de la Muerte.
Costa Rica is beautiful; I look forward to returning some day!

- Brendan

[Travel and research expenses for the field component of this trip were covered by a handful of small grants: Christiane and Christopher Tyson OTS Research Fellowship, Lewis and Clark Fund for Exploration and Field Research Grant, Sally Hughes-Schrader Travel Grant, & Explorers Club Diversa Award.]


  1. I never knew about photomorphs! How exciting. In this image, both the dark and green lobes have a similar shape. Is this always the case? If so, then it seems the fungus has complete control over morphology.

  2. Hey Bernadette,
    In general, yes, the fungus is the major determiner of the overall morphology of a lichen, and your observation regarding the photo is absolutely correct. However, there are actually some instances in which the cyanomorphs and chloromorphs take on entirely different morphologies, and were even initially classified in different genera (e.g., 'Dendriscocaulon', which is a genus created for the fruticose cyanomorphs of a few genera of typically foliose lichens). Great question!