Epiphyte Taxonomy and Evolutionary Trends

Abstract

About 28,000 species, c. 9% of all vascular plants, have an exclusively or primarily epiphytic lifestyle. In addition, there are about 800 species of hemiepiphytes in genera like Ficus, Coussapoa, or Clusia. The distribution of epiphytes among the 11 subclasses of land plants is highly biased – epiphytism is particularly prominent among polypod ferns and among monocotyledons. One family stands out more than any other among the 76 families with epiphytic members, Orchidaceae. This family alone accounts for about 68% of all species. In the following, all important families with epiphytes are briefly introduced and a detailed list of epiphyte genera with species numbers is provided. Inherent problems with the compilation of such a list are discussed as well as the likelihood of quantitative and qualitative changes in the future. Phylogenetic analyses of taxa with epiphytic and terrestrial members are the most important tool to deduce evolutionary trends, since the fossil record of epiphytes is very poor. Based on the taxonomic participation and geographical distribution I then ask the question how representative our current understanding of epiphyte ecology really is. A bibliometric analysis shows that the ecological literature of the last 120 years has been highly biased toward a few taxonomic groups and particular regions. I alert the reader that all conclusions in following chapters will inevitably carry this bias.