Kingdom Fungi
Fungi used to be classified as plants, but there are enough
differences between them that we now classify them in their own
kingdom. Below is a summary of the differences between plants and
fungi.
Plants
Fungi
Similarities
cells are eukaryotic
numerous organelles
have cell walls
most are anchored in soil or other substrate
reproduction can be sexual, asexual or both
stationary
Differences
have one nucleus per cell
often have many nuclei per cell
most are autotrophs
are heterotrophs
starch is the main storage molecule
have few or no storage molecules
most have roots
have no roots
have cellulose in cell walls
often have chitin in cell walls
some reproduce by seed
none reproduce by seed
Fungi are adapted for two main functions: absorption of nutrients and
reproduction.
Fungi are heterotrophic – they do not make
their own food like plants. When they digest
food, they digest it externally first and then
absorb them into the cells. In multi-celled
fungi, the cells that do the
absorption are called hyphae.
Together these cells form a
Figure 1: Hyphae from undergound
mesh of tissue called
mycelium. These parts are usually at or below the
surface of the ground (see below). The only visible
parts of a fungus are usually the reproductive
structures, such as a mushroom.
Figure 2: Hyphae of
puffballs
Field mushrooms are only one of many types of reproduction that is
found in Kingdom Fungi. All fungi produce spores at some point in
their life cycle. They are produced inside sporangia and are so small
that they can be carried by air currents to a new growing location.
When mushroom spores land in a suitable location, they will
germinate and grow into new hyphae. When two of these hyphae
meet in the ground, they will fuse together, becoming dikaryotic (a
cell with two haploid nuclei) and grow up out of the soil. First a button
and then a full mushroom cap and stalk will grow. As the mushroom
matures, it grows gills under the cap. These gills are where the
spores develop. When mature, a single mushroom can release as
many as two billion spores!
Life cycle of a mushroom
Cool fact: Armillaria ostoyae, the honey
mushroom, is the largest known living
organism. It grows in an aspen forest in
Washington State, and covers an area of
600 hectares, or six square kilometers.
The Importance of Fungi
The fungi that most people are aware of seem only to cause
problems: such as mushrooms on their lawn, mold on their food, or
athletes foot between their toes. However, fungi also benefit humans
directly. Yeast is used to make bread, wine, and beer, Penicillum
produces antibiotics, Aspergillus is used to flavour soft drinks. Some
mushrooms are tasty foods for humans, such as morels and truffles.
Some fungi even help break down toxic materials in dumps and
waste water treatment facilities.
The most important thing about fungi is that they are vital to
ecosystems. They help to recycle nutrients when they decompose
dead organic material. Many fungi have a symbiotic relationship with
the roots of plants. The fungi help the plants absorb minerals from
the soil while the plants provide some nutrients for the fungi. Some
seeds and plants will not grow at all without the presence of these
mycorrhizal fungi.
Classification of Fungi
Kingdom Fungi is divided into three divisions (division is the same as
a phylum):
Division Mastigomycota
- produce flagellated (motile) spores, and have cellulose cell
walls
Division Amastigomycota
- produce nonmotile spores, and have chitin cell walls
- include classes:
 Zygomycetes (bread molds)
 Ascomycetes (yeast, truffles)
 Basidiomycetes (mushrooms, bracket fungi)
Division Deuteromycota
- known as imperfect fungi
- e.g. parasitic fungi, Penicillum and athletes foot fungus
Fungi as Symbionts
Lichens:
 Highly integrated symbiotic associations of millions of algal cells
(cynobacteria and /or chlorophyta ) tangled in a lattice of fungal
hyphae (cup and/or club dungi)
 Fungi provide inorganic material and protection while the algea
provide organic materials
 Classification:
A)
B)
C)
A
Foliose (leafy)
Fruticose (shrubby)
Crustose (crusty)
B
C