XVI International Botanical Congess

Biodiversity in the lichen family Cladoniaceae in the Sonoran Desert Region is restricted to approximately 50 species in the genus Cladonia. Most of the species possess a simple morphology and cup-forming or unbranched, blunt podetia predominate. Less than ten percent of the species are branched. About half of the species are sorediate. What factors have restricted the presence in this region of other genera in the Cladoniacae? Why is the branching habit, which is common in Cladonia, poorly represented among the Sonoran lichens? Might the sorediate habit in Cladonia play a role similar to branches in lichen biology?