|The majority of mushrooms and toadstools (known
scientifically as fungi) usually appear in the Autumn in Britain, although quite a few may
be seen at other times of year.
Spring produces the St.
George's Mushroom (Calocybe gambosa), a lawn and grassland species which is very
good to eat. Another fairly common one is Entoloma clypeatum (many fungi,
including this one, do not have a common name and can only be mentioned under their less
user-friendly, scientific Latin name). The latter fungus grows under bushes belonging to
the rose family, such as Hawthorn. These two fungi belong to a section of the Fungus world
known as Basidiomycetes. However, many more of the species
commonly found in spring, belong to a different section of the fungus world, the Ascomycetes. Some of these are quite small and cup-shaped and may
or may not have a stalk.
These small 'cup' fungi, as they are known, vary from just 0.5mm
across to several centimeters. Many are very brightly coloured. They grow on all sorts of
things from decaying vegetation to rotting wood.
The group of fungi known as Ascomycetes also includes some much
larger and weirder-looking species called Morels. These can be 15cm tall, with stout stems
and caps which are grain-like in appearance. Some of these are edible and are considered
to be delicious!
The spring fungi quite often grow in the summer as well. If
conditions are suitable, autumn species may come up early and can put on quite a show.
In the autumn, mushrooms can appear in great numbers. This is
because the earth has warmed up and the weather is usually warm and damp. This encourages
fungi to grow. The majority of autumn fungi are 'mushroom' shaped, although cup fungi may
also be around. If winter is slow to come and fairly mild, some fungi may persist until
cold, frost or excess water rots them. There are some species though, which can actually
resist frost. These are the 'Winter Fungus' (Flammulina velutipes) and the Wood
Blewit (Lepista nuda). The Wood Blewit is not quite so resistant to frost, but
can often be seen in January.
All of these visible fungi we have been discussing are the fruiting
bodies of the fungus. They are actually only a very small part of the fungus. They are one
of the ways in which fungi reproduce themselves and they exist just to produce spores.
The spores, when released to a suitable habitat, send out
thread-like structures called hyphae, gradually building up a network of these threads
called a mycelium. The mycelium can eventually become vast, covering huge areas of land.
It absorbs the food it needs from its surroundings. Fungi can be divided into three main
groups depending on how they go about this. Some fungi fit into more than one group
depending on the circumstances.
- The first method of obtaining food is called 'saprophytic'
and the fungi that use this method are called saprophytes'. These are a
very important group of fungi, as without them we would be swiftly buried in leaves, dead
twigs, trees, plants, animals and other organic matter.
Fungi growing on dead wood.
- These saprophytic fungi are essential to the processes of decay.
Without them to help recycle nutrients, life on earth as we know it would cease. The
fungal mycelium absorbs the food it needs from whatever dead, rotting material it is
growing on. In so doing, the rotting remains are gradually broken down. Fungi are not the
only organisms involved in the rotting process. Bacteria and other living organisms such
as earthworms are also vitally important. Eventually, the dead, rotting material playing
host to this variety of organisms, will totally disintegrate. After all the fungi,
bacteria and other invertebrates have extracted their food, what is left returns to the
earth to act as fertilizer.
- The second group of fungi are called mycorrhizal fungi.
Like the first group, they break down organic matter, but in addition, the mycelium is
attached to roots of living trees and plants. They extract food (sugars)
that they need from these living plants, but in return they supply the host plant with
some of the nutrients and water which the plant may require. Thus both the fungi and the
plants upon which they feed, 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 all.
- The last group are called parasites. They attack and
can kill living plants, trees and other animals. Some fungi, when they have killed their
host will then employ the first method and become a saprophyte, rotting the dead host.
The mechanisms used by various species of fungi to
spread their spores are very ingenious. An ordinary mushroom releases millions of spores
from the gills, dropping them out into the air under the mushroom cap. The wind and air
currents will then carry them away.
||Puffballs and Earthstars, with the aid
of rain or water drops, puff out their spores to be similarly carried away in the air
Birds Nest Fungi have their spores in
disc-like packets in the bottom of a 'nest' structure. Raindrops falling into the
bucket-shaped nest, scoop out packets of spores and propel them several centimeters away.
||Stinkhorn fungi make use of animals to
disperse their spores. They have a green slime on top of the fruiting body which smells
revolting to us, but which flies think is delightful! They are attracted to the smell,
walk in it, eat it and then fly away to spread the spores which have stuck to their feet.
produce their spores in sacs called asci, which shoot the spores out several centimeters,
well away from whatever they are growing on.
The most spectacular display of all comes from a
very small fungus, called Pilobolus, which is shaped like a miniature light bulb.
This fungus grows on various types of animal dung (click here for a
picture). The mycelium is actually breaking down the dung so that it will eventually
be recycled and absorbed into the soil.
This little light bulb is only 3mm high and with a
little black dot on top, which is a packet of spores. The 'light bulb' builds up a
pressure of 80lbs per sq. inch (three times the pressure in a car tyre) and at about
mid-day, it explodes and propels the packet of spores up about 2 metres in the air and
along 2-2.5 metres to land on surrounding grass. Another animal will come along and eat
the grass with the spores attached to it. It passes through the gut of the animal and is
expelled in the dung, where it proceeds to develop just as before. An extremely efficient
method of ensuring the spores find their way into just the right place to grow in their
Fungi produce a staggering variety of fruiting
bodies. Fruiting bodies of one fungus or another can be found more or less throughout the
year in Britain. They come in an enormous variety of colours, shapes and sizes with many
intriguing methods for dispersing the millions of spores which they produce.
The mushrooms or toadstools which we see are the
fruiting bodies of fungi. The main part of the fungal body, or mycelium, is hidden from
view in the ground, or in rotting matter. A single mycelium may cover a very large area.
Without fungi, life on earth as we know it would not
exist. They play a vital role in decomposing dead organisms and returning the resulting
nutrients to the soil for plants to reuse. They are also vitally important for the growth
of many plants and in particular trees, which may require the contributions from their
mycorrhizal fungi in order to flourish.