the title ‘Danger! Poisonous Plants’.
One way of looking at the differences between plants, animals and fungi is to sum up their different lifestyles: plants are producers; they manufacture food by the process of photosynthesis with the help of the green pigment chlorophyll and energy from sunlight; animals are consumers that ingest their food; fungi cannot manufacture food, but instead absorb material that they break down externally, they are recyclers.
Plants and fungi can also be separated by morphological and chemical differences. Most plants are made up of cells and cellulose is a principal component of their cell walls. In contrast, most fungi (and all mushrooms and toadstools) are made up of elongated cell-like filaments, the structural component of which is largely chitin, a chemical also found in the wing cases of insects. Some fungi such as the yeasts are single celled but, in common with the filamentous fungi, they lack cellulose.
Plants, fungi and animals are termed eukaryotes: their DNA is packaged in chromosomes within nuclei. Bacteria are more primitive and lack internal structures associated with their genetic blueprint and are known as prokaryotes. It is only recently that some fungal-like organisms, the actinomycetes, have been found to be prokaryotic and are now classed along with bacteria. The strange slime moulds, which have fungal-like methods of reproduction, ingest their food in a manner similar to amoebae and have now been placed with the protozoans. Much more recently, the structure of important membranes (cristae) within the mitochondria (‘power stations’) of eukaryotes has been shown to be tubular in animals and plants, but flattened in fungi. In the 19th century, Cooke concluded:
It is exceedingly difficult to give a logical definition of what constitutes a fungus.
Spooner and Roberts, writing in 2005, were prepared to give it a try:
The Fungi comprise non-photosynthetic eukaryotes with an absorptive nutrition that do not have an amoeboid pseudopodial stage, and may occur as both single celled and multicelled organisms. The cell walls contain chitin and B-glucans, and their mitochondria have flattened cristae.
A rather more user-friendly definition is:
A very diverse assemblage of organisms and micro-organisms that obtain their nutrients from decaying organic material or from living plants, animals or even other fungi.
Other organisms that have long proved difficult to classify include the lichens, which were frequently grouped with the mosses. It is now known that a lichen consists of two organisms, a fungus and an algal component (or more rarely a type of bacterium). As the algae in lichens are capable of photosynthesis, lichens are more plant-like. As each species of lichen involves a different species of fungus, lichens are now classified by their fungal component and are included within the fifth kingdom of the fungi. Not withstanding this, the lichens differ from other fungi in many ways and have not been included in this book.
Fairy Inkcap – Coprinus disseminatus
{Laurie Campbell/NHPA}
People often express surprise that fungi have been placed in their own kingdom. This is usually because of an assumption that there are not very many different species of mushroom and toadstool, compared with the number of flowering plants.
Looking at the numbers from a British perspective, there are about 2,000 species of flowering plant growing in the wild. The recently published (2005) Checklist of the British & Irish Basidiomycota lists some 2,200 species of mushrooms and toadstools (agarics). In addition, the list includes 430 brackets and relatives, over 100 puffballs and relatives, around 100 club and coral fungi, about 20 hedgehog fungi and over 200 jelly fungi. All of the latter groups are included in books about ‘mushrooms’ together with some of the larger species of ascomycete (see here) such as the morels and truffles, taking the total number to well over 3,000 species of larger fungi. When all the lichens and smaller species of ascomycete are included along with the moulds and yeasts, together with plant parasites known as rusts and smuts we reach a figure in excess of 14,000 named species of fungi in Britain.
With the exception of garden escapees and deliberately introduced plants there have been very few newly discovered British species of flowering plant during the past 20 years. In contrast, species of larger fungi that have not previously been recorded in Britain are being discovered every year. Some of these may well be new to Britain (see here), but others represent native species that have previously escaped the attention of anyone capable of identifying them. As the number of both amateur and professional mycologists has grown so has our knowledge of the diversity of different fungal species in Britain.
Esher Common in Surrey, a 380 hectare site within easy reach of London (and the mushroom experts at Kew) has probably undergone more mycological recording than anywhere else in Britain, which means that it is possibly the best recorded area anywhere in the world. To date, over 3,200 species of fungi have been found there and new ones are being added to the list every year. The fact that there has been at least one professional mycologist based at Kew Gardens for the past 125 years, in conjunction with over a century of recording by members of the British Mycological Society, has left Britain with a wealth of fungal records.
Despite this, knowledge concerning the distribution of larger fungi in Britain is very patchy and some parts of the country are under-recorded; areas with many records may reflect the close proximity of a good mycologist rather than a region that is especially rich in fungi. Although some new records of the larger fungi reflect habitat and climate change (see pages ref1 and ref2), others are the result of keen observation and perseverance in attempts to identify species that are not featured in books about British fungi. That this can involve amateur mushroom hunters is explained in Chapter Six.
While new records of larger fungi are still relatively uncommon, the number of newly discovered species of microfungi is much higher. In many cases these prove to be not just new records for Britain, but species that are new to science. One example is a fungus that grows on the fallen leaves of woody plants with leathery leaves, including the strawberry tree (Arbutus unedo). During the time that I was writing this book I heard a programme on Radio 4 about this newly discovered species. It has very unusual spore-bearing structures, unlike any previously described. My study window overlooks the front garden, which is home to a 10-year-old strawberry tree. I am looking forward to making a close (microscopic) examination of the decaying leaves from under the plant; there is always something new to look out for in the fungus world.
One of the principal aims of naturalists has been the classification and accurate naming of species; only when this is done can we answer the question, ‘How many species are there?’ The Swedish naturalist Carl Linnaeus may have revolutionised the classification and naming of plants in the middle of the 18th century, but he never came to terms with the fungi. In 1751 he wrote:
The order of Fungi, a scandal to art, is still chaos with botanists not knowing what a species, what a variety.
In one of his publications he included the fungi under the name Chaos, and even in his magnum opus of plant classification (Species Plantarum) published in 1753, he included only 10 genera of fungi and a total of just 90 species, despite the earlier work of an Italian mycologist who had listed over 900 species. It was left to Christiaan Persoon to sort out the chaos of the fungi. The man who was to do for fungi what Linnaeus did for flowering plants was born in the Cape of Good Hope in the early 1760s, was sent as a teenager to school in Germany and finally settled in Paris. His publications included books on the lower plants and four important works on the classification of fungi. His system of fungal classification was largely based on the morphology of the fruiting bodies and most of the 100 genera that he created