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Fungi In The Scheme Of Life
Plantae
Fungi
Monera
Animalia
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Protista

Why Fungi Are Important
Important as decomposers
Spoil food
Produce antibiotics
Cause disease in plants

Why Fungi Are Important
Cause disease in animals (Athletes
foot, yeast infections, etc.)
Poison humans and animals
Important food source
Produce important fuels and
industrial chemicals (ie. ethanol)

 During the American Revolution (1775-1783),
more British ships were destroyed by wood-
digesting fungi than by enemy attack.

Fungal Characteristics
Eukaryotic
Multicellular (with one exception)
Heterotrophic
Absorb nutrients - may be
saprobes (absorb from dead
material), parasites, or mutualistic
symbionts (with algae make
lichen).

Fungal Characteristics
Secrete powerful enzymes
Cell walls contain chitin, a
polysaccharide also found in
arthropod exoskeletons
Lack flagella

Vegetative body consists of
mycelia made up of networks of
hyphae
Hyphae - Long threads of cells
designed to maximize surface
area and also transport nutrients
The Body Plan of Fungi

Hyphae
 Hyphae are designed to increase the surface area
of fungi and thus facilitate absorption
 May grow fast, up to 1 km per day, as they spread
throughout a food source
 In some fungi the cytoplasm in the hyphae are not
divided by cell walls. This continuous cytoplasm
contains several nuclei.
 In other fungi septa may be present. Septa partly
divide the hyphae into compartments but the
cytoplasm can still flow moving nutrients through
out the fungus

Classification of Fungi
 Classification of fungi is based on life cycle,
specifically reproductive structures.
 Fungi can reproduce both sexually and
asexually by means of spores
 There are three major phyla of fungi, classified
by their pattern of sexual reproduction.
 These are the conjugation fungi, the sac fungi,
and the club fungi.
 A fourth phylum called the imperfect fungi
includes thousands of fungi where their sexual
reproduction pattern is unknown.

Zygomycota (Conjugation Fungi)
Zygomycota - Zyg = yolk - Zygote
forming fungi. Eg. Rhizopus
(common bread mould)
About 600 described species
Mostly terrestrial
Root like hyphae, called rhizoids,
anchor the fungus, secrete digestive
enzymes, and absorb nutrients.

 Other hyphae,
called stolons, grow
in a network over
the surface of the
food. Give rise to
sporangiophores,
which are the
reproductive
hyphae.

 Usually reproduce asexually by spore formation.
 Conjugation occurs when hyphae of different
strains touch.
 The hyphae swell and produce a gamete-
producing structure.
 The wall between the two hyphae break and the
nuclei fuse to form a number of diploid (2n)
nuclei.
 Forms a zygospore which allows the fungus to
survive harsh environmental conditions. Will
grow again when conditions are favourable.

Ascomycota (The Sac Fungi)
 Ascomycota - Asc = sack - Truffles, yeasts,
powdery mildew, morels & cup fungi.
 Largest group of fungi
 All are multi-cellular with the exception of yeasts.

 Hyphae have septa.
 Sac Fungi produce
two kinds of spores :
Sexual spores –
ascospores
Asexual spores –
conidia
 Ascospores develop
within a saclike
ascus.

 The visible portion of the
fungus is the fruiting body
which contains the spore
bearing sacs (asci).
 Beneath the surface is a
large mycelium.
 Some members of this
group cause plant diseases.

Basidiomycota (The Club Fungi)
 Basidiomycota - Basidium = club
 About 25,000 described species including
mushrooms, toadstools, puffballs, rusts and smuts.
 Important decomposers of wood because of their
ability to hydrolyze lignin

 The fruiting body only
grows when conditions
are favourable.
 The main part of this
fungus is the mycelium
which grows
underground.
The largest living organism in the world is a club
fungus (a honey mushroom) in Oregon. It’s
mycelium covers an area of about 2200 acres; the
size of 1220 soccer fields.

 Asexual reproduction
is uncommon
 Sexual reproduction
produces basidiospores
which are produced in
the fruiting body or
“club” of the fungus.

 The mushroom consists of a stalk and a cap.
 The undersurface has many “gills” that are made
up of hyphae.
 Each gill has many basidia where the spores are
produced.

 Many types of mushrooms are edible but many are
also extremely poisonous.
 There are three main species of wild mushrooms
which can be harvested in Saskatchewan: morels,
chanterelles and pine mushrooms.
 Since the different species are harvested at different
times, these wild mushrooms can be harvested
throughout the growing season.
 Make sure you are able to positively identify any
wild mushroom you find before eating it as it may
be your last meal !!!!

Deuteromycota (Imperfect Fungi)
 Deuteromycota - Deuter = second -
The imperfect fungi
 These organisms exhibit all the
characteristics of fungi, but have not
been observed reproducing sexually
 As classification is based on sexual
reproduction, Deutoeromycetes cannot
be definitively placed in any phylum

Deuteromycota (Imperfect Fungi)
 Beneficial - Pennicillium Harmful – Athlete’s foot

Lichens
 Lichens – Symbiotic relationship between fungi and algae.
 Over 25,000 species described.
 Some lichens are estimated to be more than 4500 years
old.
 Ascomycetes are usually the fungal component although
some basidiomycetes lichens are known.
 Hyphae account for most mass.
 Fungus provides moist environment protection, support
and minerals.
 Algae provides fixed carbon (photosynthesis).

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Fungi

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