Published on

Published in: Technology, Education
1 Like
  • Be the first to comment

No Downloads
Total views
On SlideShare
From Embeds
Number of Embeds
Embeds 0
No embeds

No notes for slide


  1. 1. The Fascinating World of Fungi
  2. 2.  extraordinary organisms which are neither plants, nor animals.  one of the most important group of organisms on this planet  some of the world's largest and possibly oldest individuals  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.
  3. 3.  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.
  4. 4.  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 (large) fungi.
  5. 5.  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.
  6. 6.  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 neighboring trees.
  7. 7.  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
  8. 8.  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.
  9. 9.  Fruiting bodies of fungi will generally produce millions of spores. A single fruiting body like a mushroom, may produce more than 10,000 million spores!  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.
  10. 10. 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 as lamellae.
  11. 11. 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.
  12. 12.  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.
  13. 13.  Fungi with fruiting bodies large enough to be readily visible will usually belong to one of two main groups. The Basidiomycetes, or the Ascomycetes
  14. 14. 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 spores!
  15. 15. 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.
  16. 16. Polypores 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.
  17. 17.  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 microscopic spores.  In the Basidiomycetes, the spores are produced externally, on the end of specialized cells called basidia.  In Ascomycetes, spores are produced internally, inside a sac called an ascus.  Asci and basidia are both microscopic structures.
  18. 18. Basidiomycetes Ascomycetes Fungi with spores produced externally, on specialized Fungi with spores cells called produced inside a sac basidia. called an ascus. Typically, t Each ascus usually here are 4 contains 8 spores spores per (sometimes basidium, 4, depending on the although species). this varies from 1 to many, depending on the species.
  19. 19.  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 to 30cm.  Ascomycetes are very varied. They can be identified from the fruiting bodies which bear the asci and the way in which the asci develop.
  20. 20. •Each ascus usually contains 8 spores (sometimes 4, depending on the species) •Fungi with spores produced inside a sac called an ascus.
  21. 21.  Cup Fungi, Morels (Order Pezizales) Earth tongues (Order Helotiales) Truffles (Tuberales)  Cordyceps fungi (Order Clavicipitales) Xylaria and Daldinia (Order Sphaeriales)
  22. 22. CUP FUNGI, MORELS CORDYCEPS FUNGI (ORDER PEZIZALES) (ORDER CLAVICIPITALES) EARTHTONGUES (ORDER XYLARIA AND DALDINIA HELOTIALES) (ORDER SPHAERIALES) TRUFFLES (TUBERALES  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 ostiole.
  23. 23. Apothecium Perithecium Discomycetes Pyrenomycetes
  24. 24.  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.
  25. 25.  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 currents.  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 disperse further.
  26. 26.  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 places.
  27. 27. When they fly away, the spores will be transferred to other places.
  28. 28.  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 name.  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. 
  29. 29.  An astonishing partnership between two very different organisms  Colonies which may be 9,000 years old  Colorful dyes for clothes  Packing for ancient Egyptian mummies!  Pollution indicators  High mountain dwellers and Arctic survivors
  30. 30.  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.
  31. 31.  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 their own.  Of the more than 1500 *genera of algae worldwide, relatively few make suitable
  32. 32. Habitats  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.
  33. 33.  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 surface.
  34. 34. Crustose encrusting lichens encrusting forms which spread over and into the surface of their habitat. They cannot be removed from the surface without crumbling away.
  35. 35. Foliose leafy lichens 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.
  36. 36. Fruticose shrubby lichens lichens are shrubby forms with many branches. They can be removed from the surface by hand.
  37. 37.  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.
  38. 38.  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!
  39. 39.  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.
  40. 40.  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 colors.  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.
  41. 41.  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 CD-ROM disks!  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
  42. 42.  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.
  43. 43.  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 under alders.  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 fertilized. 
  44. 44.  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 all.
  45. 45.  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 those without.  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.
  46. 46.  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.
  47. 47.  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
  48. 48. Recycling 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 remains.
  49. 49.  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.
  50. 50.  Food 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 products.
  51. 51.  Medicines 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.
  52. 52.  Bio-control 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.
  53. 53.  Crop Diseases 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.
  54. 54.  Animal Disease 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 fungal infections
  55. 55.  Food Spoilage 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 are needed.