Myceliar Peronosporomycetes: Downy Mildews and Water Moulds

Abstract

The fungi discussed here are those commonly known as the water moulds and downy mildews. These two groups of fungi have long characterized the two subclasses, Saprolegniomycetidae and Peronosporomycetidae, respectively. Traditionally, the saprotrophic water moulds have been regarded as the less ‘advanced’. This perception may change in the light of molecular biological data now becoming available. Because they are so well known, the families and genera of both subclasses of these fungi have been regarded as stable. Molecular biological data is confounding this comfortable concept to such an extent that it is not possible, at this stage, to present a satisfactory systematic account with entries for each species. Therefore, extensive bibliographies are included here for genera because species names are not separately entered in PART V. Some of the problems are discussed in more detail below.