XVI International Botanical Congess
Area cladograms of Vanilloideae coupled with estimates of molecular divergence time indicate that Pogoniinae evolved in South America during the Cretaceous, radiated and experienced a dispersal to North America during the Paleocene. Ancestors of the temperate genera subsequently migrated north and westward. The current disjunction between Asian and North American species of Pogonia supports the theory that a vicariance event divided a once widespread temperate flora. The pattern in Vanillinae also suggests a possible origin for the subtribe in South America prior to the breakup of Gondwana. Epistephium (South America) is sister to Eriaxis and Clematepistephium (New Caledonia) and these are sister to genera from Australasia. These interpretations indicate that Orchidaceae may have evolved earlier than traditionally believed.