Fungi
The term fungus (plural fungi) includes eukaryotic, spore-bearing, achlorophyllus, organisms
that generally reproduce sexually and asexually, and whose usually filamentous, branched somatic
structures are typically surrounded by cell walls containing chitin or cellulose, or both of these
substances, together with many other complex organic molecules.
General morphology, characters and somatic structures of fungi
The thallus: Thallus is a growth form lacking differentiation into root, stem and leaves. In
fungi, it is known as somatic (soma= body) phase. It may be plasmodial, unicellular,
pseudoplasmodial or mycelial. A filamentous structure of fungal body composed of multicells
is known as mycelium (pl. mycelia) and a fragment (unit) of mycelium is called hypha (pl.
hyphae i.e. web). Hyphae or mycelia may be septate (having cross wall in the filament) or
aseptate (without cross wall or septum).
Branching habit of mycelium: Dichotomous, sympodial, lateral, opposite, verticilliate,
monopodial etc.
Other somatic structures: Rhizoides (rootlike), appressorium (pl. appressoria), haustorium
(pl. haustoria), hyphopodium (pl. hyphopodia).
Hyphal aggregations and tissues: During certain stages of life cycle, fungal mycelia become
organized loosely or compactly that form some structures called plectenchyma (i.e. woven
tissue). Its two general types are known as prosenchyma (i.e. approaching a tissue)and
pseudoparenchyma (a type of plant tissue). These two types compose various other somatic
and reproductive structures like stroma (mattress), sclerotium (hard structure) and rhizomorph
(root shaped).
Reproduction in fungi: Fungi reproduce by three processes viz., (A) Vegetative, (B) Asexual and
(C) Sexual reproduction.
Vegetative reproduction
a. Fragmentation e. Rhizomorph
b. Fission f. Chlamydospores
c. Budding g. Oidia (small egg)
d. Sclerotium
Asexual reproduction
a. Exogenous: The spores (reproductive units) borne at the tip or outside the vegetative
structure called conidia (sing. conidium i.e. dust). Two types of conidia are thallospores
and conidiospores. The letter has got three types viz., Blastospores, Aleuriospores, and
Phialospores. The bearing structure is called conidiophore (phore=bearer). Generally,
conidia are developed on a simple (without branch) tubular conidiophore. Some other types
of conidia bearing structures are phialids (small bottle type), synnema, coremia, acervulus
(heap), sporodochia, pycnidia and sori (sing. sorus) or pustule.
b. Endogenous: The spores produces in sporangia (sing. sporangium; vessel or container)
and hence called sporangiospores. Sporangiospores are of two types viz. (i) plasmospores
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, or zoospores or swarm spores which are motile due to having flagella and (ii) aplanospores
which are non-motile due to lacking flagella.
Sexual reproduction
The sexual reproduction takes place by fusion of two compatible haploid nuclei, usually the
gametes. There are two distinct fungal species
a. Monoecious or hermaphroditic: they are bisexual having both sex organs on one
thallus (homothallic).
b. Dioecious: they are unisexual having either male or female sex organs on one thallus
(heterothallic)
Four distinct phases of sexual reproduction are: somatogamy, plasmogamy, karyogamy and
meiosis. These phases occur by any one of the following five general methods of sexual
reproduction,
i. Gametic copulation – (a) Isogamy and (b) Anisogamy
ii. Gametangial contact
iii. Gametangial copulation
iv. Spermatization
v. Somatogamy (Anastomosis)
Classification of Fungi, Taxonomy and Nomenclature
A. Taxonomy and units of Classification:
Super kingdom - Eukaryonta
Kingdom - Protista (now Fungi)
Sub-kingdom - Mycota
Division - mycota (suffix)
Sub-division - mycotina (suffix)
Class - mycetes (suffix)
Sub-class - mycetidae (suffix)
Order - ales (suffix)
Family - aceae (suffix)
Genus -
Species -
Suffix are used or added to the scientific names of a taxon. A taxon (pl. taxa) is a category in the
classification system. Whittaker (1969) provided five kingdom system viz., Monera, Protista,
Plantae, Animalia and Fungi, and thus Fungi is separated from Protista on the basis of nutrition
pattern.
B. Various classifications
Classification of fungi was given by various authors viz. Gwynne-Vaughan and Barnes (1927),
Martin (1931, 1941), E.A. Bessey (1950). C.J. Alexopoulos (1962) etc. The classification
forwarded by Ainsworth (1966 and 1972) is most widely accepted that has been given below:
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, Kingdom : PROTISTA (now FUNGI)
Sub-Kingdom : MYCOTA
Division : MYXOMYCOTA (Primitive Division : EUMYCOTA (Plasmodium or
fungi, plasmoidium or pseudoplasmodium absent,
pseudoplasmodium assimilative phase filamentous)
present)
Sub-division : Myxomycotina 1. Sub-div :
Mastigomycotina
Class : Acrasiomycetes Class : Chytridiomycetes
Hydromyxomycetes Hyphochytridiomycetes
Myxomycetes Oomycetes
Plasmodiophoromycetes
2. Sub-div : Zygomycotina
Class : Zygomycetes
Trichomycetes
3. Sub-div : Ascomycotina
Class : Hemiascomycetes
Plectomycetes
Pyrenomycetes
Discomycetes
Laboulbaniomycetes
Loculoasomycetes
4. Sub-div : Basidiomycotina
Class : Teliomycetes
Hymenomycetes
Gasteromycetes
5 Sub-div : Deuteromycotina
Class : Blastomycetes
Hyphomycetes
Coelomycetes
Nomenclature
Naming of fungi and their classification fall under the rule of International Code for Botanical
Nomenclature. The scientific name of an organism follows the pattern of binomial (bi = two+
nomen = name) nomenclature system, which is composed of two words. The first word designates
the genus and the genus name is always capitalized. The second word designates the species and
its name is not capitalized. Binomials when written are underlined and when printed italicized.
Modification or updating, if any, in the nomenclature is done by a Committee for Fungal
Nomenclature at each International Botanical Congress held at every four years interval.
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The term fungus (plural fungi) includes eukaryotic, spore-bearing, achlorophyllus, organisms
that generally reproduce sexually and asexually, and whose usually filamentous, branched somatic
structures are typically surrounded by cell walls containing chitin or cellulose, or both of these
substances, together with many other complex organic molecules.
General morphology, characters and somatic structures of fungi
The thallus: Thallus is a growth form lacking differentiation into root, stem and leaves. In
fungi, it is known as somatic (soma= body) phase. It may be plasmodial, unicellular,
pseudoplasmodial or mycelial. A filamentous structure of fungal body composed of multicells
is known as mycelium (pl. mycelia) and a fragment (unit) of mycelium is called hypha (pl.
hyphae i.e. web). Hyphae or mycelia may be septate (having cross wall in the filament) or
aseptate (without cross wall or septum).
Branching habit of mycelium: Dichotomous, sympodial, lateral, opposite, verticilliate,
monopodial etc.
Other somatic structures: Rhizoides (rootlike), appressorium (pl. appressoria), haustorium
(pl. haustoria), hyphopodium (pl. hyphopodia).
Hyphal aggregations and tissues: During certain stages of life cycle, fungal mycelia become
organized loosely or compactly that form some structures called plectenchyma (i.e. woven
tissue). Its two general types are known as prosenchyma (i.e. approaching a tissue)and
pseudoparenchyma (a type of plant tissue). These two types compose various other somatic
and reproductive structures like stroma (mattress), sclerotium (hard structure) and rhizomorph
(root shaped).
Reproduction in fungi: Fungi reproduce by three processes viz., (A) Vegetative, (B) Asexual and
(C) Sexual reproduction.
Vegetative reproduction
a. Fragmentation e. Rhizomorph
b. Fission f. Chlamydospores
c. Budding g. Oidia (small egg)
d. Sclerotium
Asexual reproduction
a. Exogenous: The spores (reproductive units) borne at the tip or outside the vegetative
structure called conidia (sing. conidium i.e. dust). Two types of conidia are thallospores
and conidiospores. The letter has got three types viz., Blastospores, Aleuriospores, and
Phialospores. The bearing structure is called conidiophore (phore=bearer). Generally,
conidia are developed on a simple (without branch) tubular conidiophore. Some other types
of conidia bearing structures are phialids (small bottle type), synnema, coremia, acervulus
(heap), sporodochia, pycnidia and sori (sing. sorus) or pustule.
b. Endogenous: The spores produces in sporangia (sing. sporangium; vessel or container)
and hence called sporangiospores. Sporangiospores are of two types viz. (i) plasmospores
1
, or zoospores or swarm spores which are motile due to having flagella and (ii) aplanospores
which are non-motile due to lacking flagella.
Sexual reproduction
The sexual reproduction takes place by fusion of two compatible haploid nuclei, usually the
gametes. There are two distinct fungal species
a. Monoecious or hermaphroditic: they are bisexual having both sex organs on one
thallus (homothallic).
b. Dioecious: they are unisexual having either male or female sex organs on one thallus
(heterothallic)
Four distinct phases of sexual reproduction are: somatogamy, plasmogamy, karyogamy and
meiosis. These phases occur by any one of the following five general methods of sexual
reproduction,
i. Gametic copulation – (a) Isogamy and (b) Anisogamy
ii. Gametangial contact
iii. Gametangial copulation
iv. Spermatization
v. Somatogamy (Anastomosis)
Classification of Fungi, Taxonomy and Nomenclature
A. Taxonomy and units of Classification:
Super kingdom - Eukaryonta
Kingdom - Protista (now Fungi)
Sub-kingdom - Mycota
Division - mycota (suffix)
Sub-division - mycotina (suffix)
Class - mycetes (suffix)
Sub-class - mycetidae (suffix)
Order - ales (suffix)
Family - aceae (suffix)
Genus -
Species -
Suffix are used or added to the scientific names of a taxon. A taxon (pl. taxa) is a category in the
classification system. Whittaker (1969) provided five kingdom system viz., Monera, Protista,
Plantae, Animalia and Fungi, and thus Fungi is separated from Protista on the basis of nutrition
pattern.
B. Various classifications
Classification of fungi was given by various authors viz. Gwynne-Vaughan and Barnes (1927),
Martin (1931, 1941), E.A. Bessey (1950). C.J. Alexopoulos (1962) etc. The classification
forwarded by Ainsworth (1966 and 1972) is most widely accepted that has been given below:
2
, Kingdom : PROTISTA (now FUNGI)
Sub-Kingdom : MYCOTA
Division : MYXOMYCOTA (Primitive Division : EUMYCOTA (Plasmodium or
fungi, plasmoidium or pseudoplasmodium absent,
pseudoplasmodium assimilative phase filamentous)
present)
Sub-division : Myxomycotina 1. Sub-div :
Mastigomycotina
Class : Acrasiomycetes Class : Chytridiomycetes
Hydromyxomycetes Hyphochytridiomycetes
Myxomycetes Oomycetes
Plasmodiophoromycetes
2. Sub-div : Zygomycotina
Class : Zygomycetes
Trichomycetes
3. Sub-div : Ascomycotina
Class : Hemiascomycetes
Plectomycetes
Pyrenomycetes
Discomycetes
Laboulbaniomycetes
Loculoasomycetes
4. Sub-div : Basidiomycotina
Class : Teliomycetes
Hymenomycetes
Gasteromycetes
5 Sub-div : Deuteromycotina
Class : Blastomycetes
Hyphomycetes
Coelomycetes
Nomenclature
Naming of fungi and their classification fall under the rule of International Code for Botanical
Nomenclature. The scientific name of an organism follows the pattern of binomial (bi = two+
nomen = name) nomenclature system, which is composed of two words. The first word designates
the genus and the genus name is always capitalized. The second word designates the species and
its name is not capitalized. Binomials when written are underlined and when printed italicized.
Modification or updating, if any, in the nomenclature is done by a Committee for Fungal
Nomenclature at each International Botanical Congress held at every four years interval.
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