Part 3 gives keys, descriptions, and discussions for 239 moss species. In addition, for each species precise type information is provided; distribution within Central America is documented by the examination of specimens; world distribution is indicated; habitat notes based on personal field experience or taken from collection labels are provided; and a list of previously published illustrations is given. This volume contains numerous genera that treat all tropical American species of those genera, as well as major treatments on Lepidopilum (18 species), Thamniopsis (13 species), Pireella (11 species), and Porotrichum (11 species); it will likely prove useful for many genera throughout the Neotropics.

Bryophytes are of great importance in their ecosystems and for human well-being. They stabilize soil crust through colonization of bare grounds and rocks; they are essential in nutrient recycling, biomass production, and carbon fixing; they control water through an effective retention mechanism; and they have economic value as peat for fuel, horticulture, oil absorption, and as sources of a wide variety of chemical compounds. Bryophytes have long been used for medicinal purposes and provide a food source for reindeer, geese, ducks, sheep, musk-ox, lemmings, and other rodents. Threats include deforestation, cultivation of forests, reclamation of land, urbanization, roads, dam-building, mining, drainage of wetlands and over-grazing. This plan reviews the situation worldwide and proposes a variety of initiatives. It is aimed at those who work with and care about nature conservation, including governmental and non-governmental organizations as well as politicians and the general interested public.