The mosses of Big Bend National Park: a phytogeographic study

The phytogeographical affinities exhibited by the intra-and interfloristic relationships of the mosses of Big Bend National Park are reported. A checklist of elements making up the moss flora of the 708,281 acre Big Bend National Park was compiled from identifications of collections made in each physiographic and vegetational area in the Park. In addition, herbarium specimens collected by previous workers were annotated to make the checklist as complete as possible. One hundred seven species, four varieties and one hybrid, representing twenty-one families and fifty-seven genera are reported. A bryogeographic analysis of each family, genus and species is reported to indicate origin and floristic history of each taxon and the flora as a whole. A new method for determining centers of speciation for the various families is developed. World and North American distributional analyses of each taxon are presented to indicate interfloristic relationships exhibited by this moss flora. World distributional analysis divides the taxa into seven groups: Endemic, Cosmopolitan, Northern Hemisphere, Pantropical, North American, Central and South American and Discontinuous Distributions. Northern Hemisphere taxa, Central and South American taxa and Cosmopolitan taxa are the largest groups in this flora. North American distributional analysis divides the taxa into six groups: Widespread, Northern, Eastern, Western, Southwestern and Mexican. The Mexican taxa and Southwestern taxa represent the largest groups in this moss flora. Relationships exhibited by this flora to other adjacent and distant North American floras are also presented. Comparisons of the distributions of the mosses and vascular plants of Big Bend National Park are made and similarities in the North American distributions of these two groups are discussed. Floristic evidence of past migrations, invasions and interfloristic influences are combined with the present distributional analyses to suggest the possible origin and evolution of the flora of Big Bend National Park