Field Mycology 1 January 2000 AN INTRODUCTION TO CORTICIOID FUNGI Alick Henrici This article is addressed to those who find it treated alphabetically. In Nordic Macro- difficult to identify any corticioid fungus with mycetes Vol. 3 (NM3) corticioids are more confidence. ‘Corticiology’ is always likely to boldly grouped in various places throughout remain a minority interest even within the the book reflecting their supposed relation- minority interest that is mycology since there ships, interspersed with polypores etc. are major hurdles to be jumped to get into Some corticioids have been suspected to the subject. Once in however, it is a fascinat- have close relatives with very different ing and rewarding field. morphology. Thus Ramaricium is a corticioid genus with all the microscopic characters of What are corticioids and where do they Ramaria, while Gloiothele lactescens has fit? amyloid ornamented spores and emits a It doesn’t do to question too closely just what whitish liquid when squashed which even is meant by a corticioid fungus. The only smells and tastes like the milk of Lactarius sensible answer to “What is a Fungus?” is quietus. Molecular studies are now beginning well known to be “Anything studied by to confirm that some of these ‘anecdotal’ mycologists”. In a similar vein the only relationships are in fact absolutely real. sensible answer to “What is a corticioid?” is There is then the further question whether in “Anything included in Corticiaceae of North these cases the corticioids are ‘reduced Europe (CNE)”. There is, in fact, a contin- forms’ of the more structured species uum from smooth through merulioid to (comparable to the various genera of minute poroid forms connecting corticioids such as gill-less reduced agarics) or whether, as Phlebia or Phanerochaete to pored fungi such seems more likely, evolution led in the as Gleoporus or Ceriporia. Any demarcation opposite direction and Ramaria, Lactarius line will be arbitrary and the question of etc. evolved from different groups of corti- where to draw it is not one of importance. cioid ancestors. While such questions have in If the limits of corticioids are vague, so too the past been entirely matters of speculation, are the relationships between them, which they seem likely soon to receive incontrovert- provide a fascinating puzzle that is only just ible answers. If the whole aggregate of the beginning to be resolved. In the traditional Agaricales, the Aphyllophorales and the treatment offered by Rea (British Gasteromycetes do indeed have a single Basidiomycetae, 1922) the corticioids common ancestor, there is a good chance it (broadly defined) were a unit, a single family was some lignicolous saprophyte with a corti- Thelephoraceae, taking their place alongside cioid growth form. other families of the Aphyllophorales, such as There are about 350 corticioid species Clavariaceae, Polyporaceae and Hydnaceae, known in Britain, around a half of all the based on general fruitbody morphology. It is ‘Aphyllophorales’. Only round numbers are now realised that such groupings are only appropriate as both groups are artificial and skin deep. The ‘Gasteromycetes’, for without precise boundaries. Quite a number instance, are known to have evolved along of species have only been added to the British several different lines from different groups list in the last ten years or so. There must be of agarics and other fungi. They cannot be many more to come. The total compares accommodated in a single taxonomic group. with around 500 species in Scandinavia, Thc corticioids and polypores are similar where they have been studied fairly inten- cases. Relationships are still so little under- sively over the last forty years. stood that in CNE, the genera are merely 12 Field Mycology 1 January 2000 Arguments in favour able within each genus in Nordic When compared with agaricology, corticiol- Macromycetes Vo1. 3 (NM3), which includes ogy has much to recommend it: almost everything British and is highly • The chances of making significant finds are recommended, but arriving at the right much higher. Over large parts of the country genus is often difficult. Inevitably, in a work almost any record will be a new county of this size, there is insufficient information record! about each species to give the user much • This is an all-the-year-round subject. Prime confidence, having arrived at a determina- sites for corticioids are the undersides of tion, that it is, in fact, the correct one. The large logs. These will only be found frequency information in NM3 is a decided unrewarding during long periods of drought. asset. To a large extent, species recorded as • Collections do not have to be looked at with common in Denmark will also be common the same urgency as freshly gathered agarics. here, while species unknown in Denmark will This is not to say they should be left around be rare or unknown here. If you reach an for a week, either inside or outside the fridge. apparently rare species, be suspicious! NM3 Such treatment leads to collapsed basidia, cites illustrations from Breitenbach & strange hyphal outgrowths and much wasted Kränzlin, Fungi of Switzerland Vo1. 2, which time when identification is belatedly provides further essential reading. It gives attempted. However if they are promptly photos, drawings and quite full descriptions dried, they will lose few of their characters of around half the British species. and be no harder to identify under a micro- scope than when fresh. On not getting discouraged • While even the experienced corticiologist There is an interesting passage in CNE l:36 will identify relatively few species in the field, that reads: “It is no use to wander over vast they are rather more likely than agarics to areas turning one log here and another there. display striking features under the micro- It is better to do some walking before you scope. A Clitocybe unidentified in the field is start collecting and then find a place you feel apt to remain so in the lab; not so with a is suitable. Then stay there and act as a corticioid. vacuum cleaner. If it is a good collecting • The literature is much less extensive and place you will find new specimens for at least contradictory than for the agarics. There are half the day amounting to some 50-100 fewer synonyms and doubtfully defined samples.” The present writer remembers first species to deal with. Species concepts are reading this at a time when he was apt to often broader. spend a long evening struggling with no more than three specimens, only to end up with Getting started one probable identification, one long shot This is the problem area. Excellent identifi- and one still with no clues at all. Even 50 cation literature exists in the form of samples cheerfully collected in a morning Corticiaceae of North Europe (CNE), complete looked like providing a month’s hard work. in eight softback volumes, with superb You have to have faith that the process does microscopic drawings of all the species very soon become much quicker with experi- covered (including almost everything ence. Even so, a half-day in the field can British). Unfortunately there are two major easily generate two days at the microscope drawbacks. Most volumes of the set are now and still leave some issues unresolved. out of print, and even once obtained the keys There are several prerequisites for achiev- to genera in Vol. l are off-putting to the begin- ing a fast enough work rate to make the ner. The good news is that a replacement is whole exercise rewarding: in preparation, based on this work but • To see the essential structures at all clearly, extended to all of Europe. It is planned to you will need a good cell-wall stain (e.g. come out in two volumes in the near future. Congo Red), either that or phase contrast In the meantime, identification will remain optics on your microscope. a problem. There are now good keys avail- • You will also need some self-confidence in 13 Field Mycology 1 January 2000 your microscope technique. Any key will refuse to soften. They break cover slips. inevitably ask whether clamps and cystidia Eventually, they reveal mainly amorphous or are present (clamps are much easier to see crystalline matter. You give up, but in fact than on the swollen hyphae of agarics). You you haven’t given yourself a chance. This need to believe you would have seen cystidia material probably fruited a month ago. You if any had been present, etc. etc. can’t identify it, not from any inadequacy in • It is probably also essential to own a dissect- yourself or your literature, or your micro- ing microscope. Slides made with a fine scope, but because it long ago ceased to be in scalpel under a magnification of x20 or x30 an identifiable state. Choose instead are likely to be far more informative than something thin and soft from under a log. A squashes of arbitrary chunks picked off the small portion will lift off easily onto a hymenium at random. moistened scalpel and give a really informa- • Don’t waste time struggling with poor tive slide with no trouble at all. Now you are material. Collections that don’t promptly in business! reveal basidia and spores will seldom be identifiable with confidence and should Where to collect? usually be discarded without more ado. For many a field mycologist, the answer will • More than anything, what is needed is be obvious: it will be in their favourite woods simply more experience. Fairly soon a where they have already recorded widely in number of species will become familiar. other groups. But if the choice is wide open, Inspection under the dissecting microscope there are other factors to consider.