Flora of Australia Volume 51: Mosses 1 is the first of three volumes describing and illustrating more than 1000 species of Australian mosses. Together they will represent the first national account of these diverse and ecologically significant organisms. The main features of the first volume are: an introduction documenting 200 years of research on Australian mosses; moss classification and an overview of morphology and sexuality; an account of ecology and biodiversity; the origin and evolution of mosses; fossil bryophytes; and a key to the more than 300 genera of mosses known from Australia and its island territories. This volume includes traditional, Flora of Australia-style descriptions of 22 families, 42 genera and 238 species and infra-specific taxa, including synonymy, specimen citations and notes on habitat and distribution. Distribution maps are provided for species and infra-specific taxon as well as more than 50 pages of line-art illustrating habit and anatomy and 64 colour photographs.