Orchids of Assam: A Pictorial Guide is a comprehensive photographic and taxonomic treatment with an updated enumeration of the orchids of Assam. It aims at providing the readers with information about the orchids of Assam in detail with colour pictures, colour plates of flower sections and drawings. It furnishes a general introduction, a brief description of Assam with climate, vegetation, botanical history of orchid study, habitat and orchid population, ethnobotany, threats and conservation of orchids within Assam. It includes the morphology of orchids followed by a detailed analysis of 395 specific and 10 intraspecific taxa belonging to 101 genera of native orchids of Assam. The life form, growth habit, morphology and pollination of orchids have been discussed under the heading "morphology". A large number of figures of the habit, inflorescence, flower and lip have been provided to show the diversity in the vegetative and floral forms of orchids. All the species and genera are enumerated alphabetically. In the enumeration, while a generic name is provided with the author citation and generic description only, a species binomial is followed by author citation, species description, flowering and fruiting, habitat and general distribution. The description for all the species has been drawn from the live plants along with colour plates made from fresh flowers for these orchids. It will serve as a comprehensive identification guide not only for botanists worldwide, but also for foresters, nature lovers, orchid lovers, nursery workers and amateur orchid growers.