A comparision of ghost orchid (Dendrophylax lindenii) habitats in Florida and Cuba, with particular reference to seedling recruitment and mycorrhizal fungi

The ghost orchid, Dendrophylax lindenii, is a rare, leafless epiphyte native to southern Florida and Cuba. Populations of D. lindenii in southern Florida and Cuba are separated by c. 600 km and occur in different habitats. We describe D. lindenii in its natural habitats in the Florida Panther National Wildlife Refuge and Guanahacabibes National Park, Cuba. Population size, fungal endophytes and seedling recruitment are also discussed. In total, 116 individuals of D. lindenii were recorded in Florida during July 2015, whereas only 16 specimens were known to occur there previously. In Cuba, 241 individuals were counted, nearly one-third (30.3%) of which were seedlings (nearly double the percentage of seedlings documented in Florida; 16.4%). In Florida, D. lindenii grew on just two host tree species, Fraxinus caroliniana and Annona glabra, most (69%) on the former, whereas in Cuba 18 tree species acted as hosts, primarily Maba crassinervis (16.2%), Erythroxylum aerolatum (15.4%) and Comocladia dentata (14.9%). More than half (55.2%) of D. lindenii individuals in Florida (55.2%) and Cuba (52.7%) were documented on the north-facing (NW, N, NE) bark of host trees. Significant differences (P = 0.035) were detected in directional orientation between the two sites, with Cuban orchids preferring NE, N and E and those in Florida preferring NW, NE and SW surfaces. Roots from mature D. lindenii in Florida yielded an endophyte identified as a strain of Ceratobasidium. We propose that D. lindenii colonizes host trees with moist, corrugated or semi-corrugated bark harbouring Ceratobasidium for seed germination.