In this article we will discuss about the general features of lower fungi.
The lower fungi comprise the simplest and the primitive group of true fungi represented by about 1,500 species. The majority of these are aquatic (Saprolegnia), some are amphibious (Phytophthora) and some terrestrial (Rhizopus).
They live either as strict parasites or saprophytes. Strictly parasitic species live on algae, ferns and seed plants. A number of them cause diseases of economic plants, such as the downy mildew of grape, brown rot of lemon and potato blight.
All of these were first recognised as a coherent group in 1873 by the German mycologist Heinrich Aton De Bary. He placed them in the class Phycomycetes (Gr. phykos meaning alga, mycetes meaning mushrooms, fungi, and hence alga-like fungi). Popularly they are called the algal fungi because they bear a striking resemblance to some of the algae (Vaucheria) in morphology of the thallus and sex organs.
The lower Fungi or Phycomycetes are:
(a) The somatic phase consists of either a unicellular thallus or a non-septate coenocytic mycelium. The septa usually remain suppressed in the actively growing stage.
(b) Asexual reproduction takes place by sporangiospores and sometimes by conidia. The sporangiospores are motile (zoospores) in aquatic species and non-motile in the terrestrial species.
(c) The spore producing units are usually not grouped into a complex fructification.
(d) Sexual reproduction, when present, is either isogamous or heterogamous.
(e) Karyogamy generally follows plasmogamy almost immediately so that there is no dikaryophase in the life cycle.
The Lower Fungi (Phycomycetes) include the simplest members of true Fungi. The most primitive among them are the aquatic species. The common examples of Lower Fungi are the black molds, water molds, downy mildews and white rusts.