A complete monographic treatment of Pterostylis. Covers the historical background, classification, distribution, floral morphology, biology, ecology and phylogeny of Pterostylis. Many features are illustrated using line drawings and scanning electron micrographs. A total phylogenetic analysis based on morphological and DNA sequence data identifies 16 groups in two major lineages with Pterostylis. Detailed drawings are provided for the type species of each genus and a separate drawing shows a longitudinal section of a flower either of the type species or of a species representative of each genus. Contains a synopsis of the new interpretation of the subtribe Pterostylidinae. Complemented with colour plates.