The below mentioned article provides biology notes on lower fungi.
They have comparatively a simple thallus which in some is unicellular and in others filamentous (mycelium). The septa usually remain suppressed in the actively growing vegetative mycelium.
They reproduce asexually by sporangiospores (generally motile, rarely non-motile), rarely by conidia. The early mycologists placed the lower fungi in a single class Phycomycetes which is split in this text into the following six classes on the basis of presence or absence of motile cells in the life cycle and the number, form and position of flagella on motile cells.
Motile Cells Produced:
1. Class Chytridiomycetes:
Included in this class are the lower fungi in which motile cells have a single flagellum of whiplash type inserted at the posterior end (opisthocont). The members of this class are called the chytrids.
2. Class Hyphochytridiomycetes:
The motile cells (zoospores) possess a single flagellum of tinsel type which is inserted at the anterior end.
3. Class Plasmodiophoromycetes:
The motile cells (zoospores) are biflagellate. Both the flagella are of whiplash type but one of these is longer than the other. The longer one has a sharply pointed end and the shorter one has a blunt end. The club root organisms are the examples of this class.
4. Class Oomycetes:
The motile cells are biflagellate. The two flagella are usually of nearly equal length. One of these points forwards and the other trails behind. The former is of tinsel type and latter of whiplash type. The common representatives of this class are the water molds, downy mildews and blights.
Motile Cells Lacking:
5. Class Zygomycetes:
Motile cells are absent. Asexual reproduction takes place by sporangiospores which are encapsulated and wind disseminated. The common examples are the pin molds and the bread molds.
6. Class Trichomycetes:
The motile cells are lacking. The asexual spores are produced exogenously at the tips of special hyphae (conidiophores) and are called the conidia.