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extraordinary organisms which are neither plants, nor
one of the most important group of organisms on this
some of the world's largest and possibly oldest
fairy rings, right out of children's story books
hallucinogenic magic mushrooms
some are silent killers with deadly poisons.
a vital ingredient in beer and bread.
decomposers, essential for natural recycling, helping to
guarantee life on earth.
miracle cures for disease.
indispensible partners for many plants.
Fungi cannot make their food from sunlight, water
and carbon dioxide as plants do, in the process
known as photosynthesis. This is because they lack
the green pigment known as chlorophyll, which
plants use to capture light energy. So, like
animals, they must obtain their food from other
organisms. They do this in three ways. They may
break down or 'rot' dead plants and animals.
Organisms which obtain their food this way are
known as 'saprophytes'. Alternatively they may feed
directly off living plants and animals as 'parasites'. A
third group is associated with the roots of plants in
what are termed Mycorrhizae.
There are literally thousands of different kinds of
fungi. Worldwide, 200,000 species have been
described. It is estimated that there may actually
be as many as 1 - 1.5 million species.
In Britain there are more than 20,000 species of
fungi. Most of these are micro-fungi, too small to
be easily noticed. Approximately 3,000 are macro
The main body of most fungi is made up of
fine, branching, usually colorless threads called
hyphae. Each fungus will have vast numbers of
these hyphae, all intertwining to make up a tangled
web called the mycelium.
The mycelium is generally too fine to be seen by the
naked eye, except where the hyphae are very closely
packed together. The picture on the left was taken
through a microscope. The hyphae are magnified
100 times life size.
Some fungi, such as Honey Fungus, which is a
parasite of woodland trees, have hyphae collected
together into long cables, called rhizomorphs.
Because there are so many hyphae packed together,
they are easily seen, forming black 'bootlaces'.
These can spread through a woodland infecting
Fungal mycelium is mostly hidden from human
view, not only because of its small size, but also as a
result of its location. The tangled mycelia mass is
usually hidden deep within its food sources, such as
rotting matter in the soil, leaf litter, rotting wood, or
dead animals. The mycelium remains undetected
until it develops one or more fruiting
bodies, containing the reproductive spores
There are literally thousands of different kinds of fungi. Two
hundred thousand species have been identified world wide
and there are likely to be well over a million species.
We identify different species mostly by the structure of their
fruiting bodies and the arrangement and types of spores
which they produce.
There are a great many fungi which are very small
(micro-fungi). They will not be covered here. However,
there are many other fungi with large enough fruiting bodies
to be easily seen.
Many fungi have fruiting bodies e.g. a mushroom which are
stalked. This helps to raise the spores some distance off the
ground, so that when they are released, they can easily catch
wind currents and be carried to new places.
Fruiting bodies of fungi will generally produce millions
of spores. A single fruiting body like a
mushroom, may produce more than 10,000 million
Even though they are tiny, finding room for all these
spores on a relatively small fruiting body presents a
major problem. The fruiting bodies of fungi are
therefore cleverly engineered to provide space for the
production of enormous numbers of spores, without
having to produce an enormous fruiting body to
accommodate them all. Different types of fungi have
accomplished this in different ways.
Fungi such as mushrooms, have hundreds
of paper-thin folds, called gills, on the
underside of the mushroom cap. The spores
are produced all over these gills, which
provide an enormous surface area base for
the spores. Gills are sometimes also known
Some other fungi have small tubes or
pores within the fruiting body. The
spores develop all over the inside of
the pores, which again help to
produce a large surface area.
Still other fungi have developed fruiting
bodies covered with enormous numbers of
tooth-like structures which bear the
spores. Others just have large numbers of
folds all over the fruiting body. All of these
different methods for increasing surface area
of the fruiting body and the different
structures which result, provide a useful
way to identify different kinds of fungi.
Fungi with fruiting bodies large
enough to be readily visible will
usually belong to one of two main
groups. The Basidiomycetes, or
This type of fungus includes our familiar edible
mushroom. Most, but not all gill fungi, have a stem
bearing a cap on top. The gills, or lamellae as they
are also known, are on the underside of the cap. The
spores line the surface of the gills. A single fruiting
body may produce as many as 10,000 million
These are fungi which have fruiting bodies similar to many of
the gill mushrooms, in that they have a cap and a stem.
However, boletes do not have gills on the undersurface of the
cap. Instead, they have thousands of tiny tubes arranged
perpendicular to the surface of the cap. The underside of the
cap thus looks as if it is covered with thousands of little holes,
or pores. Each hole is the end of one of the tiny cylinders,
which is lined with spores.
Polypores tend to have very tough, leathery or
woody fruiting bodies. They are often plate-like
and most grow out of tree trunks or rotting wood,
although some may grow on soil. Some of these
fungi are known as Bracket Fungi, because they
look like shelves growing out of the sides of trees.
Fungi with sporophores (fruiting bodies) large enough
to be readily visible will usually belong to one of two
main groups. The Basidiomycetes or the
Ascomycetes. The main difference between these two
groups is in the way in which they produce their
In the Basidiomycetes, the spores are produced
externally, on the end of specialized cells called
In Ascomycetes, spores are produced internally,
inside a sac called an ascus.
Asci and basidia are both microscopic structures.
Fungi with spores
produced inside a sac
called an ascus.
Each ascus usually
here are 4
contains 8 spores
4, depending on the
from 1 to
Ascomycetes are 'spore shooters'. They are fungi
which produce microscopic spores inside
special, elongated cells or sacs, known as
'asci', which give the group its name. As the spores
mature within an ascus, increasing fluid pressure
builds up inside until eventually the top bursts
off, rapidly releasing the spores. In some
species, the spores may be shot out distances of up
Ascomycetes are very varied. They can be identified
from the fruiting bodies which bear the asci and the
way in which the asci develop.
•Each ascus usually
contains 8 spores
4, depending on the
•Fungi with spores
produced inside a sac
called an ascus.
CUP FUNGI, MORELS
XYLARIA AND DALDINIA
The asci are arranged in a The asci are grouped
layer on the surface of the together into flask-shaped
fruiting body. structures known as
In the cup fungi, asci are perithecia.
found packed together into These are sunk into the
a layer which lines the surface of the fungal
inside surface of a cup- fruiting body. They open
shaped disc. to the outside through a
small hole, known as an
Most fungi rely on gravity to carry their spores down and
into air currents which will then carry them away to
other places. Gill fungi, boletes and polypores all have
their spore producing surfaces on the undersurface of the
fruiting bodies, so that the spores drop out into air
currents below. Many of the fruiting bodies also have a
stalk. This helps to raise the spore producing surface
higher up and so increase the chances of the spores
dispersing far and wide.
The fact that spores fall out under gravity can be used to
good effect to produce spore prints. This is done by
collecting the fruiting bodies of fungi such as gill
fungi, boletes or polypores and placing the cap or spore
producing surface onto a piece of paper. White paper is
usually best, although some fungi may have white
spores, in which case, black paper will show them up.
Puffballs and earthstars, employ a different method
to disperse their spores. In these fungi, the spores
are held in a mass inside a more or less spherical
ball. There is a small pore in the wall on the top of
the ball. Raindrops or animal contact placing
pressure on the top of the ball will force the spores
inside to puff out and be carried away by air
In earthstars, the outer wall splitting and opening
into a star shape has the effect of raising the fruiting
body higher above the leaf litter. There will be more
air currents higher up which help the spores to
Fungi such as stinkhorns use insects to disperse
their spores. The stinkhorn fruiting body has a slimy
spore mass which smells like carrion. This attracts
insects which normally feed on carrion, particularly
flies and as they walk around in the spore
mass, spores stick to their feet and bodies. When
they fly away, the spores will be transferred to other
When they fly away, the spores will be
transferred to other places.
Ink Caps use a quite different method to disperse their
spores. They are gill fungi in which the gills break
down as they mature. This results in a dripping black
inky fluid containing the spores. At one time this fluid
was used as ink, giving these fungi their common
Bird's Nest fungi produce fruiting bodies which
resemble a bird's nest. These are hollow structures
containing small hard packets of spores called
peridioles. Rain drops in heavy storms splash into the
'nest' structure ejecting the peridioles some distance
from the fruiting body.
An astonishing partnership between two very
Colonies which may be 9,000 years old
Colorful dyes for clothes
Packing for ancient Egyptian mummies!
High mountain dwellers and Arctic survivors
Lichens present a very intriguing problem for people
whose job is to name different kinds of organisms. This is
because a lichen is not a separate organism in the sense of
being one type of individual. It is actually a close
partnership between a fungus and an alga. (Algae are
very simple plants).
The two types of organisms in the partnership are so
closely interwoven that they appear as a single individual.
This individual looks entirely different to either of the
partner organisms making up the structure. Lichens are
distinctive and they form many different, recognizable
types. Many of these have been given specific names of
their own, despite the fact that each lichen is already a
mixture of different species.
Approximately 18,000 species of lichen have been
described and identified worldwide. The algal
partners in lichens can be found living on their own
in nature, as free-living species in their own right.
The fungal partners in British lichens are
recognizable Ascomycetes or Basidiomycetes.
However, they have come to need the right kind of
algal partner in order to survive. Unlike other fungi
or indeed their algal partner, they cannot survive on
Of the more than 1500 *genera of algae worldwide,
relatively few make suitable
Lichens colonize some of the most inhospitable
habitats on earth. They can survive in extremely
cold areas such as on high mountains and in
regions such as the arctic. They may be virtually
the only plant form surviving in some of these
areas and can be vitally important sources of food
for animals. They are also found throughout less
extreme climates, inhabiting just about any solid
surface. This can range from rocks on sea shores,
to walls, trees and concrete. A few are unattached
and blow about freely.
Lichens have a variety of different growth forms.
The simplest lichens are crusts of loosely mixed
fungal hyphae and algae. Others are more complex,
with leafy or shrubby forms like miniature trees,
also having specialized structures to attach them to a
encrusting forms which spread over and
into the surface of their habitat. They
cannot be removed from the surface without
lichens with leafy lobes, which spread out
in a horizontal layer over the surface. They
are attached by root-like threads and can be
easily removed with a knife.
lichens are shrubby forms with many
branches. They can be removed from
the surface by hand.
Lichens reproduce either by tiny parts of the lichen
breaking off and growing somewhere else, or by the
fungal partner producing spores. Lichens may have
powdery masses on their surface. These are the tiny bits
of the lichen body which will be shed to form new lichens.
The individual bits are called soredia and they contain
both the fungus and the algal partner together.
In most cases, fungal spores are either produced in
apothecia or perithecia on the surface of the lichen. The
spores come only from the fungal partner and do not
contain any algal cells. They may germinate after being
shed from the fruiting body, but they will only be able to
form a new lichen if they happen to make contact with a
suitable algal partner. Without the alga, the germinating
spore will die, as the fungus cannot survive on its own.
Lichens grow relatively slowly. The actual growth rate depends both
on the species and on the environmental conditions around it. The
smaller encrusting lichens may grow as little as 1mm a year! Larger
forms may grow up to 1cm per year.
This slow growth rate has been used to develop a method of dating
surfaces on which lichens are growing. The method, known as
lichenometry, has been used in places such as the arctic, where
lichens grow very slowly and can live for very long times. The
method works by using a series of photographs over a period of time,
to work out the growth rate of the particular lichen. From the size of
the lichen, it is then possible to calculate how long it has been
growing there. Using this method, some individual lichen colonies
have been estimated to be 9000 years old. If this is so, then these
particular lichens may well have been alive while people were still in
the Stone Age and woolly mammoths roamed!
Lichens absorb water and minerals from rainwater and
directly from the atmosphere, over their entire surface
area. This makes them extremely sensitive to atmospheric
pollution. As a result, there are usually very few lichens
around industrial centers and towns.
Different lichen species vary in their tolerance to
pollution and therefore make very good biological
indicators of levels of atmospheric pollution.
A walk around your local churchyard can often reveal a
lot about air quality in your area. Churchyards are
usually relatively undisturbed areas, with stone
headstones which provide a good substrate for lichens. A
good look at these lichens will give an indication of how
good the air quality is locally.
Lichens have had a wide variety of uses over the
ages. Before the advent of modern dyes they were
extremely important sources of dyes for clothing.
Different lichens yielded different dye colors and
they could be mixed to produce a wide variety of
Lichens also have an interesting chemistry and
produce a large number of acids, many of them
found only in lichens. The litmus dye used so widely
as an acid/alkaline indicator in chemistry comes
from lichens. Some species also have antibiotic
properties. Some of the lichen acids are utilized in
drugs that can be more effective than penicillin.
Fungi can be found in just about any habitat you
care to mention, from sea water through to
freshwater, in soil, on plants and animals, on human
skin and even growing on microscopic crevices in
Most of the fungi you would find in these places
however, are very small and would need a
microscope or magnifying lenses to see. The
following discussion on fungal habitats concentrates
on macro fungi, that is, those with fruiting bodies big
enough to be easily seen
Woods and meadows are the best places to go hunting for
fungi. Of the two, woods are by far the best place to look, as
over 80% of fungi are associated with trees.
Some fungi, such as the Fairy Ring Toadstool, Marasmius
oreades, and the edible field mushroom, Agaricus
campestris, prefer open, grassy places.
Also watch out for a different group of fungi which grow on
animal dung. These tend to have very specific habitat
requirements and you will usually find that particular species
will grow only on a certain kind of dung, at a particular stage
of decay. In order to identify the fungus, you may first need
to identify the type of dung!
Fungi are common in woodlands because of all the rotting
wood and leaf litter, which provides a wide range of the dead
organic matter which most fungi feed on.
Many fungi are also associated with trees because they are linked
into the tree roots. The association benefits both the fungi and the
trees. This particular type of association between fungi and the roots
of plants such as trees, is known as a mycorrhiza.
Some fungi have very specific associations and will grow only with
one kind of tree, for example, the bolete, Uloporus lividus, grows only
Other fungi may be found in association with several different trees.
Chanterelles, for example can be found linked with birch, pine, oak
and beech trees.
Soil type is also important. Some fungi may be associated with a
particular tree, but only where it is growing on suitable soil. The
most important factor is usually whether the soil is acidic or
calcareous (chalky). Soil fertility also plays a part. Fields which have
been heavily fertilized with artificial nitrates are less likely to be good
mushroom hunting territory than those which have been organically
Mycorrhizae are associations between fungal hyphae and
the roots of plants. Almost all terrestrial plants, including
wild plants, trees and commercial crops will form
mycorrhizal associations with fungi in the soil. These
Mycorrhizae are vitally important for the growth and
health of the plants.
The fungi extract food (sugars) that they need from the
plants, but in return they supply the plants with some of
the nutrients and water which they may require. Thus
both the fungi and the plants flourish because of the
association. This is known as a symbiotic relationship.
Certain plants, such as orchids, are totally dependent on
a fungus associated with their roots in order to grow at
Through their enormous collecting network of hyphae
in the soil, the fungi help to supply nutrients, especially
phosphorus, to the plant roots they are associated with.
This can have amazing effects on plant growth,
particularly in soils which are not very fertile. In soils
containing little phosphorus, plants with Mycorrhizae
have been shown to grow up to 20 times faster than
The survival of plant seedlings may also be up to five
times greater if they have Mycorrhizae to help them
collect nutrients and water from the soil. Helping
plants to obtain phosphorus from the soil may also give
them increased drought tolerance, as this is one of the
effects of improved phosphorus nutrition.
Mycorrhizal fungi can often form associations with many
different kinds of plants at the same time. The fungal hyphae
of several different kinds of fungi may therefore be like a giant
underground network connecting most of the plants in a
habitat together. It is possible, although not proven, that this
enables different plants to exchange nutrients between them
via the fungal hyphae. If this is so then this would hugely
improve the chances of seedlings surviving, because they are
not just dependent on their tiny root system, but have access to
the great underground collecting network.
The presence of a good network of mycorrhizal fungi in the
soil is therefore of vital importance for good plant growth in
most habitats. Where the fungi are absent, or only present as
isolated spores in the soil, plant growth will be reduced, apart
from those species which do not require mycorrhizae. Most of
these are what are commonly termed weed species.
Mycorrhizae also help to develop good soil structure through
production of a protein which helps to stick small particles of soil
together to form larger ones. This means that water can move more
easily through the soil and provides more air spaces and thus air, for
soil organisms and plant roots.
There are several different kinds of mycorrhizae. In some, the fungal
hyphae actually enter the cells of the plant roots. These are called
endomycorrhizae. There are several different kinds of these
endomycorrhizae, of which a type abbreviated to AM (Arbuscular
Mycorrhizae), is perhaps the best known. Eighty percent of the
world's plant species, from grasses, to trees, most crop plants, shrubs
and flowers, form AM associations.
Another type is called an Ectomycorrhiza (ECM). In this kind, the
fungus forms associations with plant roots, but does not actually
enter the root cells. This kind is mostly formed with different types of
trees, such as pines, firs, spruces and oaks, amongst many others.
ECM fungi may form thick hyphal strands known as rhizomorphs
which can conduct water and nutrients relatively long distances.
Many of the fungi common in woodland are ectomycorrhizal
fungi, with mushroom or toadstool-like fruiting bodies
Fungi, together with bacteria, are responsible for
most of the recycling which returns dead material to
the soil in a form in which it can be reused. Without
fungi, these recycling activities would be seriously
reduced. We would effectively be lost under piles
many meters thick, of dead plant and animal
Mycorrhizae and plant growth
Fungi are vitally important for the good growth of
most plants, including crops, through the
development of mycorrhizal associations. As plants
are at the base of most food chains, if their growth
was limited, all animal life, including human, would
be seriously reduced through starvation.
Fungi are also important directly as food for
humans. Many mushrooms are edible and different
species are cultivated for sale worldwide. While this
is a very small proportion of the actual food that we
eat, fungi are also widely used in the production of
many foods and drinks. These include cheeses, beer
and wine, bread, some cakes, and some soya bean
Penicillin, perhaps the most famous of all antibiotic drugs, is
derived from a common fungus called Penicillium. Many
other fungi also produce antibiotic substances, which are
now widely used to control diseases in human and animal
populations. The discovery of antibiotics revolutionized
health care worldwide.
Some fungi which parasitize caterpillars have also been
traditionally used as medicines. The Chinese have used a
particular caterpillar fungus as a tonic for hundreds of years.
Certain chemical compounds isolated from the fungus may
prove to be useful treatments for certain types of cancer.
Fungi such as the Chinese caterpillar fungus, which
parasitize insects, can be extremely useful for
controlling insect pests of crops. The spores of the
fungi are sprayed on the crop pests. Fungi have been
used to control Colorado potato beetles, which can
devastate potato crops. Spittlebugs, leaf hoppers and
citrus rust mites are some of the other insect pests
which have been controlled using fungi. This
method is generally cheaper and less damaging to
the environment than using chemical pesticides.
Fungal parasites may be useful in bio-control, but
they can also have enormous negative consequences
for crop production. Some fungi are parasites of
plants. Most of our common crop plants are
susceptible to fungal attack of one kind or another.
Spore production and dispersal is enormously
efficient in fungi and plants of the same species
crowded together in fields are ripe for attack. Fungal
diseases can on occasion result in the loss of entire
crops if they are not treated with antifungal agents.
Fungi can also parasitize domestic animals causing
diseases, but this is not usually a major economic
problem. A wide range of fungi also live on and in
humans, but most coexist harmlessly. Athletes foot
and Candida infections are examples of human
It has already been noted that fungi play a major role in
recycling organic material. The fungi which make our
bread and jam go moldy are only recycling organic
matter, even though in this case, we would prefer that it
didn't happen! Fungal damage can be responsible for
large losses of stored food, particularly food which
contains any moisture. Dry grains can usually be stored
successfully, but the minute they become damp, moulds
are likely to render them inedible. This is obviously a
problem where large quantities of food are being
produced seasonally and then require storage until they