Synopsis Polymorphic ferns of Western Ghats, South India is a book with complete details on the taxonomy, cytology and ecology of ten species complexes of ferns. Approximately about 20 different morphological characters have been studied in about 1000 specimens, a result of intensive field work. The extent of variations in all the species complexes is established for the first time. This would help botanist lacking field knowledge when describing new species and thereby avoid many taxonomic confusions. Western Ghats, South India with high species diversity typifies a tropical region. So far diversity has been known only at the species level and in this book for the first time diversity at the intraspecific level is dealt with. The presumed causative agents of the variations, the environmental and genetical factors are established. The climatic factors such as temperature, rainfall, humidity for a span of 10 years is included. Nomenclatural uncertainties of the ten species complexes are settled. There are exhaustive references to literature from research Journals, Scientific magazines, periodicals and proceedings.