Part 6 of the Flora of Chiapas is the first publication in the series that contains accounts of more than a single family (Part 2 did not treat genera of pteridophytes within families). This permits the timely publication of several smaller families that have been prepared for the Flora. An account for each of these five families is presented in its entirety by one or more specialists familiar with the plants in southem Mexico. Treatments for at least four other families, large and small, are being prepared for future parts of the Flora.