The mosses of Central America form one of the richest moss floras in the Neotropics. The Moss Flora of Central America is a revisionary flora, that is to say a rigorous scientific account of the 921 moss species found in Central America, analyzed from field, herbarium, and literature sources. This fourth part is the final section of the flora. The Moss Flora of Central America is based upon the study of historical collections held in major U.S. herbaria as well as recent collections made by the author and colleagues. It authenticates modern species names, while accounting for older non-valid names, gives detailed descriptions of each plant's form, an account of the habitat and ecology of each species, provides the distribution of the species both within Central America and world-wide, and presents detailed discussions of the unique features of each species as well as the best ways of distinguishing species from each other. Differences between moss species are often difficult to discern, and so each species in the flora is illustrated with a full page of line drawings. Also, lists of all previous illustrations of the species are given. Publication of the Moss Flora of Central America is in English, with the text of the flora and accompanying specimen databases also available on the web. The flora is available in Spanish, and this version of the flora can also be accessed on the web. The Moss Flora of Central America will stimulate the study of mosses throughout the Neotropics by providing in a single reference (in English and Spanish) diagnostic keys and descriptions to all the mosses in the region. It will involve the naming of large numbers of un-named collections that have accumulated in herbaria over the last twenty-five years. These collections, as well as duplicate material that will be widely distributed, will form the basis of a primary reference collection that will greatly enhance the ability of scientists to recognize species throughout the Neotropics. This will allow mosses to be meaningfully incorporated into many other interdisciplinary studies, most notably ecological studies. Furthermore, this assessment of Central American mosses can also be used to support or criticize studies done with other forms of plants or even animals in the region. Mosses occupy microhabitats that are extremely sensitive to changing physical conditions. In this time of suspected global warming and the uncertain impact of global climatic changes on world ecosystems, the Moss Flora of Central America will provide critical baseline bio-data from a crucial and ecologically sensitive part of the world. This baseline data in conjunction with future studies on the mosses of Central America will be useful in assessing the effects of climatic changes in this critical region of the world.
