Notes on The Kingdom Fungi
 
Characteristics of Fungi:
 
1. Fungi are eukaryotic
2. The majority are multicellular ( yeast is single celled)
3. Lack chlorophyll
4. Nutritionally they are heterotrophic, they digest food outside the body and absorb it . They are saprophytes, parasites and some are mutualistic.
5. Their basic body plan constitutes a mass of netlike filaments called hyphae. The entire mass is called the mycelium. Most fungal hyphae are divided into cells by cross walls called septa. Some fungi are aseptate, lacking cross walls. They are said to be coenocytic. Some types of fungi contain lateral hyphae that absorb nutrients from other organisms, called haustoria.
6. Reproduction is accomplished by the release of sexual or asexual spores. For many species of fungi sexual reproduction is a contingency used when environmental conditions are difficult. Under favorable conditions asexual spores are produced by the millions and dispersed over a large area.
Haploid conditions prevail in the life cycles of most fungi. Conjugation occurs in many fungal species.
 
Diversity of Fungi:
 
Fungi are classified into units called Divisions. There are 4 divisions based primarily on variations of sexual reproduction. The names of the divisions are based on the sexual structure that characterizes that group of fungi.
 
1. Division Zygomycota: These are mostly terrestrial fungi that live in soil or on decaying plant or animal material. Their hyphae are coenocytic, with many haploid nuclei. Asexual spores, usually wind swept, are produced by structures called sporangia, at the tips of aerial hyphae. Sexual reproduction involves the formation of resistant bodies called zygosporangia that can remain dormant when the environment is too harsh for growth. Examples are black bread mold ( Rhizopus stolonifer).
 

 
 
Division Ascomycota: These are sac fungi. They range from unicellular yeast to large cup fungi. The sexual reproductive structure is the asci, a small sac like structure. These asci are packed into large fruiting structures called ascocarps. The hyphae are multicellular septate structures. They lack sporangia but reproduce asexually by producing chains of spores at the tip of specialized hyphae. These spores are called conidia. Two types of spores are produced by this type of fungus, conidia and ascospores. Conidia are asexual, while the ascospores are sexual.
 
Reproduction of Ascomycetes:
 

 
 
These fungi are important in decomposing lignin and collagen of dead plants and animals. Some are mutualistic ( lichen) and many are parasitic to plants ( powdery mildew and Dutch elm disease).
 
Division Basidomycota: The mushroom, shelf fungi, puffballs and stink horns are examples of this division. The name is derived from the sexual reproductive structure called the basidium. The club like shape gives the name to some of the most common fungal types in this division.
 
Reproductive cycle of the mushroom:
 
 

 
 
 
Division Deuteromycota: These organism have no known sexual life style. They are also known as fungi imperfecti. Examples of this group are Penicillium and Arthrobotrys.
 
 
Lichens: Highly integrated symbiotic associations of millions of algal cells tangled in a lattice of fungal hyphae. Classification: leafy ( foliose), fruticose ( shrubby), and crustose ( crusty).
 
Mycorrhizae: mutualistic association of a fungus and a root. 90% of the fungi is bascidomycota