Collins Mushroom Miscellany. Patrick Harding

recognised today.

      The next great taxonomic mycologist was born in the last decade of the 18th century and had a background that was remarkably similar to that of Linnaeus, who was born nearly 90 years earlier. Like Linnaeus, Elias Fries was born in southern Sweden and was the son of a clergyman. Both men went to the same school and ultimately both became Professor of Botany at the University of Uppsala. Fries recorded the event that was to start his interest in fungi. As a 12-year-old he was picking wild strawberries when he found a large specimen of a species of Hericium, a beautiful creamy-white fungus that looks like a cross between a coral and a mass of stalactites.

      As with the method Linnaeus used to classify plants, many of the fungal classification schemes devised by Fries are now little used, but his knowledge of fungi enabled him to describe, name and study nearly 5,000 species, including many from outside his native country. Fries concentrated on the agarics (mushrooms and toadstools), where he was the first person to use spore colour to separate different groups, a feature still considered important by modern taxonomists. Fries died in 1878 and so was a contemporary of two of Britain’s great 19th century mycologists, the Reverend Berkeley and Mordecai Cooke (see here).

      Because there was a long-held belief that fungi were the result of the devil’s work, the study of fungi was not approved by the Church until the 19th century, by which time knowledge about mammals, birds and flowering plants was already at an advanced stage. Watling has commented that as a result of this the scientific understanding of fungi lags 100 years behind that of many organisms.

      The 20th century continued to produce eminent European and North American mycologists. Of the latter, one character was Curtis Lloyd who, before he died in 1926, became one of the leading experts in puffballs and their relatives. He once bought the stock of a failed shoe shop for the sake of the boxes to house his collection. He was not above playing a joke on his fellow mycologists and even named a fictitious puffball Lycoperdon anthropomorphus.

      Good and Bad Mushrooms (c. 1900)

      {Archives Charmet/BAL}

      The work of European and American mycologists has resulted in a fairly good knowledge of at least the larger fungi in many northern temperate parts of the world. Despite this there is a paucity of information about fungi in tropical and subtropical regions, where the diversity of plant and animal species is at its greatest. It is for this reason that estimates of the total number of fungal species in the world remain guesswork. Writing in 1981, Rod Cooke introduced his book Fungi with:

      There are over 50,000 known kinds of fungi, and it has been estimated that about 200,000 more await discovery.

      A quarter of a century later the number of known, named species is in the region of 100,000, and the total has been estimated to be closer to 1.5 million different species. The figure of 1.5 million has been arrived at by observations, spanning a range of habitats, that the number of fungal species is, on average, six times greater than the number of flowering plant species. This ratio also works for Britain as a whole, as there are approximately 12,000 named species of fungus and some 2,000 species of flowering plant.

      Some scientists believe that the global figure for the number of fungal species may be much higher, particularly as many insects, mosses and ferns appear to harbour unique, but largely unstudied, species of fungus. One estimate has put the worldwide fungal species count as closer to 9 million. Whatever the true figure there is plenty of work to be done: every year mycologists at Kew name about 1,500 new species, collected from all over the world. That we may have named as few as 1% of the world’s fungal species is indicative of just how little we know.

Fungi, Folders and Files

      Section of an Ascomycete Fungus showing ascospores

      {M I Walker/NHPA}

      The information stored in a computer needs to be readily accessible. To ensure this, individual inputs are given file names and grouped with other similar files in a named folder. Folders are themselves grouped under named categories, one example being the different users of the computer. This hierarchical pigeonholing of data into discrete bundles is analogous to the methods of classification into groups (taxa) used by taxonomists seeking to categorise species of living organism. Just as different computer users have different systems of grouping their stored information, so taxonomists differ in the way that they classify organisms. It is only since the latter part of the 20th century that the fungi, the group that include mushrooms, have been placed in their own discrete folder, often referred to as the fifth kingdom (see here).

      The problem for mycologists is how best to place the world’s 100,000 named species (equivalent to 100,000 files) into groups (folders, etc.) that reflect the similarity and evolutionary relationship of the species within each group. Given that the scientific names (and as a result the common names; see here) of species reflect the groups into which they are placed, the classification system has important knock-on effects.

      Until relatively recently all major groups of the fungal kingdom were separated by features such as the shape of the fruitbody and colour of the spores, or by details visible with an ordinary microscope. The latter includes the nature of the spore-producing tissue, the size, shape and ornamentation of the spores and details of the hyphal threads. Such classification systems invariably resulted in assemblages of fungi that had only one thing in common: they did not fit anywhere else. Most systems were far from perfect. The use of the electron microscope, chemical analysis and, above all, genetic analysis including the sequencing of DNA has resulted in a major regrouping of many fungal species. One result of this reclassification has been a change to the scientific names of some fungi, including species of mushroom and toadstool. In addition, some species formerly included within the fungal kingdom have been moved to other kingdoms.

Most mycologists now recognise five main groups (phyla) within the fungal kingdom. These are Basidiomycota, Ascomycota, Glomeromycota, Zygomycota and Chytdridiomycota.

      Members of the Basidiomycota produce sexual spores on the surface of special club-shaped cells known as basidia. The agarics, a historical term for mushrooms and toadstools with a mushroom-shaped fruitbody, belong in the Basidiomycota, in a class known as the basidiomycetes. Older schemes divided the agarics into some five orders, largely based on spore colour. Current thinking is to have just three orders: one order includes the boletes, such as the edible cep (Boletus edulis), with tubes in place of gills; a second embraces the crumblecaps (Russula spp.) and milkcaps (Lactarius spp.), typical of woodland habitats; and a third includes all other agarics.

      The basidiomycetes also include puffballs and their relatives, bracket and crust-forming fungi, club and coral fungi, and most of the larger jelly fungi. Two other classes of Basidiomycota include the rusts, smuts and other plant parasites; in total, around 500 British species of microfungi which, unlike the basidiomycetes, do not produce large fruitbodies.

      Candlesnuff fungus – Xylaria hypoxylon

      {Stephen Dalton/NHPA}

      Members of the Ascomycota, usually referred to as the ascomycetes, produce sexual spores inside elongated sac-shaped cells known as asci. This group includes morels and truffles which, along with some cup-fungi such as orange-peel fungus (Aleuria aurantia), have relatively large fruitbodies and are usually included in books about mushrooms. The ascomycetes also embrace thousands of species of cup fungi with miniature fruitbodies only a few millimetre across, most of which grow on rotting plant material.