Myxomyceta

(also Mycetozoa, Myxothallophyta), slime molds, a division (phylum) of nonchlorophyllous fungiform organisms. Of the approximately 400 species, most are cosmopolitan. They exist vegetatively in the form of multinucleate protoplasmic masses (plasmodia), measuring from several millimeters to 1 m long; the vegetative stage is diploid. The reproductive stage is characterized by membranous spores; a motile, naked, biflagellate cell (rarely more than one) emerges from each spore. After several divisions the cells, without changing or losing their flagella, are transformed into myxamoeba and function as gametes to form zygotes. The zygotes fuse to form a plasmodium, which lives within the substrate or moves slowly along its surface. The plasmodium, or a part of it, is subsequently transformed into a brightly colored sessile (or stalked) sporangium with spores.

Myxomyceta usually develop on rotting wood or other plant remains in forests and damp places. Most species are saprophytic. Some cause crop diseases, for example, potato scab and clubroot of cabbage.