The kingdom Fungi is divided into four main classes in NCERT: Phycomycetes, Ascomycetes, Basidiomycetes and Deuteromycetes. These classes differ mainly in their mode of nutrition and mode of reproduction.
| Class | Mode of Nutrition | Mode of Reproduction |
|---|---|---|
| Phycomycetes | - Mostly saprophytic on decaying organic matter - Some are obligate parasites on plants | Asexual: By motile zoospores or non-motile aplanospores produced endogenously in sporangia. Sexual: By fusion of gametes; may be isogamous, anisogamous or oogamous; forms a thick-walled zygospore. |
| Ascomycetes | - Mostly saprophytic (decomposers) on dead organic matter - Some are coprophilous (growing on dung) - Some are parasitic on plants | Asexual: By conidia (asexual spores) produced exogenously on special hyphae called conidiophores. Sexual: By ascospores produced endogenously in sac-like asci, usually contained in fruiting bodies called ascocarps. |
| Basidiomycetes | - Mostly saprophytic decomposers on soil, logs or tree stumps - Many are parasitic on plants (rusts and smuts) - Some form symbiotic associations (e.g., mycorrhizae) | Asexual: Generally uncommon; asexual spores are usually absent; reproduction may occur by fragmentation of mycelium. Sexual: Sex organs are absent; sexual reproduction occurs by plasmogamy between compatible hyphae leading to a prolonged dikaryotic phase and formation of basidia, each producing four basidiospores exogenously. |
| Deuteromycetes (Fungi Imperfecti) | - Mostly saprophytic, growing on leaf litter and organic debris - Some are parasitic and may cause diseases - Many act as important decomposers | Asexual: Only asexual reproduction is known; occurs by conidia (conidiospores). Sexual: Sexual reproduction is absent or not yet observed; hence called “Fungi imperfecti”. |