What have the fungi ever done for us?

Fans of Monty Python may remember a sketch from ‘Life of Brian’ where Reg (John Cleese) and the team were decrying the behaviour of the omnipotent Roman empire by asking the rhetorical question: 'what have the Romans ever done for us?'. Only to be forced to admit that without their innovations, life as they knew it, would be very different and a lot harder.  Well I think the case can be easily made that fungi have done even more for us than the Romans did without the more unsavoury downsides of life in Roman times.

The wonder that is Fungi

Fungi is a very diverse kingdom of organisms ranging from single celled yeasts, through moulds that are multicellular with long filamentous structures (hyphae), to the more complex mushrooms and toadstools that we admire at this time of year. 

But what do they do for us?

Well, we are all familiar with the benefits of yeasts, such as for making bread or beer but they are also extensively used in the biotechnology industry for production of enzymes and pharmaceuticals.  They also have potential application in in helping us to clean up our environment such as bioremediation for removal of heavy metals from water.  Some filamentous moulds, a group that includes penicillium also have great potential for green production of bulk chemicals as an alternative to the petroleum-based industry we have all become so dependent upon.

However, probably the most important role of fungi is that they, along with bacteria, are the major decomposers in most ecosystems and therefore are an essential part of the process of recycling nutrients and making them available for plants. In other words, plants, and therefore animals, could not exist without fungi.  This is taken to the next level by the many complex symbiotic relationships between plants and fungi.  It has been estimated that over 90% of plant species in terrestrial ecosystems have a dependant relationship with mycorrhizal fungi and could not flourish without them.  It is understood that the role of the mycorrhizal fungus is to help the plant with uptake of inorganic nutrients, especially in nutrient poor soils.  It has also been observed that mycorrhizal networks help with uptake of water during periods of drought.  Additionally, fungi present within tissues of the plant may also protect it to some extent from being eaten by animals.  In return it is thought that the fungi benefit by getting organic carbon from the plant. 

In the very complex relationships between mycorrhiza and orchids it has been shown that, as well as providing nutrients and supporting water uptake, the fungus enables germination of the orchid seeds and protocorm development by providing carbon compounds too.  It has even been discovered that in species such as the Coralroot Orchid, the mycorrhizal fungus can transfer carbon from nearby tree roots to the orchid.

What about mushrooms and toadstools?

The reason that most people, myself included, develop an interest in fungi is from seeing the large numbers of toadstools that appear in our gardens and woodlands in the autumn.  They have an amazing diversity of form and colour which complements and enhances our appreciation of the seasonal changes. 

These toadstools are the fruiting bodies of an amazing network of hyphae that intertwine with plant roots and soil particles in the ground below.  Many are saprobic, breaking down dead plant material but some are also mycorrhizal.  Most of the structures that we recognise as toadstools are from a group of fungi called basidiomycetes.  So-called, because they form spores outside the cells on structures called basidia.  For these fungi, when the toadstool is ripe, the spores drop down and are passively distributed by the wind.  Each individual network of hyphae may produce multiple fruiting bodies and spread over quite a large area.  This can be easily seen from the rings of toadstools that appear in grass.  On poor soils the ring is also associated with brighter green grass demonstrating the fungi is supporting the growth of the grass.  Some hyphal networks can be very large and it has been reported that one single network covered an area of several square kilometres.

Mushrooms for meadows

There are a wide variety of fungi that are associated with grassland and meadows.  These are most abundant where the land has been left undisturbed for many years and has not been fertilized (unimproved).  This is not too surprising when we understand the complex relationships between fungi and plants and also the networks of hyphae that inhabit the soils below the sward.  The most obvious toadstools found in grassland are large such as the impressive Parasol (Macrolepiota procera) whose caps are often up to 25cm in diameter and 30 cm tall.  I found one of these giants a couple of years ago just down from the top of Roundton Hill although the ones in our meadow are not quite that impressive.  Similarly large is the Horse mushroom which together with the more diminutive Field Mushroom make an excellent and easily identifiable culinary treat.

Colourful Waxcaps

However, if you get down and look amongst the grass and mosses you will find the real specialists of the autumn meadows, the waxcaps.  These are all members of the Hygrophoraceae family.  So named from the Greek “Hygros”, meaning wet or moist, as except in very dry conditions, their caps all have a moist shining surface.  Apart from the somewhat larger Meadow Waxcap (Cuphophyllus (Hygrocybe) pratensis), most of these remain within the sward and are less than 5cm high with caps 1 – 3cm in diameter.  However, the colour range is spectacular with every thing from the normal browns to bright yellows, greens and scarlet.  There’s even a pure white one appropriately named the Snowy Waxcap (Cuphophyllus virgineus).  As I implied earlier, these fungi are good indicators of established and undisturbed meadows, although if you are lucky you will probably be able to find a few on uncut patches in your lawns or local parks, particularly if  they haven’t been treated with pesticides or fertilisers.  So, get down close to the grass and have a good look!

Everything that looks like a fungus may not actually be one

When you start to look more closely at what is growing amongst the grass you can find some strange looking things.  In our meadow at this time of year, you can see quite a few patches of what look like clumps of white jelly like roots sticking up about 5 cm in short grass.  These are appropriately named, White Spindles (Clavaria fragilis) and are another indicator of unimproved grassland.  Although very different to look at, this species is still in the same phylum as the mushrooms and toadstools.  However, if you search on some old stumps at the edge of the field you will most likely find another white spindly fungus but this time, dryer looking, and with black colouration at the base.  This also has a descriptive common name, Candlesnuff Fungus (Xylaria hypoxylon) but is from a completely different phylum: Ascomycetes.  In these fungi the spores form inside the tissue of the fungus in sacks called asci and are forcibly ejected from them into the air.

Occasionally when you look amongst the grass you may see something that looks like a granular white splatter of semolina.  Others refer to it as looking like animal vomit and one of its common names is Dog Sick Slime Mould (Mucilago crustacea); although I have to admit that the vomit our dog produces never looks like that!  Interestingly, slime moulds, although sharing some of the characteristics of fungi, are in fact members of a completely separate kingdom: Protista, a part of the amoebozoan domain.  These curious organisms normally exist as single cells and can move around in response to chemical and other stimuli to feed on microorganisms living on decaying material.  I believe that this creamy-white mass is the result of an aggregation of cells to form a plasmodium which in turn has transformed into a spore producing structure analogous to the toadstools of fungi.

Don’t fungi cause plant diseases?

As a gardener I have to admit that sometimes fungi, especially those that cause blackspot on my roses and blight on my tomatoes can be a bit of an irritation but in reality, it is all our own fault.  In a natural ecosystem the complex relationship between fungi and plants has reached a point of perfect harmony and mutual benefit.  However, as gardeners, we bring in foreign plants from different ecosystems, and we should not be surprised that they are not adapted to live with our local fungal fauna.  Similarly, when serious plant fungal diseases like Ash dieback (Hymenoscyphus fraxineus) get introduced into the UK from other continents, our indigenous species have not had a chance to evolve effective defence mechanisms and are seriously impacted.  The solution is to look after our soils, support our indigenous fungal communities to live in balance with our indigenous plant species and minimize the introductions of exotic plants which risk introducing harmful fungal diseases and also are likely to be more susceptible to infection from local ones.

I would like to believe that this blog has provided an interesting introduction to appreciation of the world of fungi and that I have convinced you of how important fungi are to our biosphere.  I also hope that I have encouraged you to explore your garden and surroundings to see what you can find and help you to get more pleasure from the natural world around you. 

Disclaimer

Any views or opinions represented in this blog are personal and belong solely to the author and do not represent those of people, institutions or organizations that the author may or may not be associated with in professional or personal capacity, unless explicitly stated