Cattleyas are frequently called "the Queen of the Orchids," and Carl Withner's passion for them started before World War II. About 12 years ago he published the first in this series of six books, which now comes to a conclusion with this final volume. The South American Encyclia species have not previously been the subject of a book, and the genus presents many problems and difficulties. A few of the species are known from a single herbarium specimen and may well now be extinct because of the continuing loss of habitat.

This volume also includes taxonomic and nomenclatural changes affecting species covered in the earlier volumes, as well as additions and changes to the text of each of the five volumes.