The family was erected by Fries in Systema Mycologicum, volume I of which was published in 1821. Under the International Rules of Botanical Nomenclature this work becomes the starting point for nomenclature of the family; consequently names which were published prior to that date may be disregarded. Under this family Fries placed species in which the hymenium of the fructification is carried in narrow pores inserted in the usually ventral portion. In the three volumes of the Systema Fries recognised five genera—Cyphella, Daedalea, Lenzites, Polyporus and Solemnia, though he dispersed them among several families; and in later works added Favolus and Irpex (1828), Cyclomyces (1830). Trametes (1838) and Polystictus (1851). Ten genera in all.
Genera were delimited by Fries on such macrofeatures as pore form and texture of the context; species on pileus shape, size, colour, and whether stalked, sessile, or resupinate. Such were possibly adequate features for the relatively few species then known from Europe: in fact, there was little else to employ, as at that period the microscope was little better than a toy. As more species were recognized, especially when the wealth of forms from the tropics were collected, it became evident to students that the few genera of Fries were inadequate for taxonomic purposes. Furthermore, since Fries did not define his genera adequately, their interpretation has subsequently provided a problem for taxonomists, aggravated by the fact that type species and type collections were not indicated, nor in many cases preserved.
Consequently later mycologists attempted to improve upon the several systems published by Fries, notably Karsten (1879. 1881. 1889). Quelet (1886), Patouillard (1900). Murrill (1907–08, 1914, 1942). Ames (1913), Donk (1933), Pilat (1936–1942) Cooke (1940), and Bondarzew & Singer (1941). Most arranged genera upon macrofeatures, their numbers ranging from a modest 16 to 90. None of these classifications enabled one to identify species accurately, or defined genera so that species could be placed under them without some degree of confusion. In the result when I commenced to study Australasian species in 1946 a thorough search was made of the literature to ascertain if other methods of classifying genera and species could be found. A promising field appeared in two papers published by E. J. H. Corner (1932a, 1932b), who dealt with anatomical details of a few species, a new field of study in the family. Some six months were spent examining anatomical details of 350
species then available. It was found that genera could be defined by certain anatomical features; and species identified so readily that later when working through Australian and New Zealand collections in Kew herbarium, it was possible to name all but half a dozen despite that most were represented by single specimens, often poorly preserved, or fragmentary.
Corner, in his two now classical papers, described the anatomy of three species. He showed that in “Polystictus” xanthopus three series of hyphae composed the fructification. These he named skeletal, binding, and generative. Skeletal hyphae provided a rigid framework, binding hyphae held the first together and formed most of the tramal walls upon which the hymenium developed, generative hyphae supplied the hymenium and surface tissues. In Fomes laevigatus and F. senex Corner. found that there were two hyphal series. skeletal and generative. He therefore postulated that one, two, or three hyphal systems were involved in forming the fructification of different species in the family. These he named respectively monomitic, dimitic and trimitic hyphal systems, thus:
|Hyphal System||Hyphal Series|
|Monomitic||Generative hyphae only.|
|Dimitic||Skeletal and Generative hyphae.|
|Trimitic||Skeletal, Binding and Generative hyphae.|
My studies (1947–1950) confirmed those of Corner. They showed that three hyphal systems were involved in producing the fructification of different species, exactly as Corner had forecast; that not more than three were involved. Furthermore, certain fundamental differences were noted between species with brown and with hyaline hyphae (as seen under the microscope), mainly in the presence or absence of clamp connections and correspondingly of the number of nuclei in the hyphal cell. These differences are fundamental, and useful as aids in segregating certain genera and species into related groups. They are shown in tabular form, thus:
Monomitic Hyphal System: Champ connections present in hyaline hyphae (or if absent replaced with bridging hyphae); clamp connections absent from species with brown hyphae.
Dimitic Hyphal System: Clamp connections present in hyaline hyphae (or replaced with bridging hyphae); clamp connections absent from species with brown hvphae.
Trimitic Hyphal System: Clamp connections present in generative hyphae of species with hyaline or brown skeletal and binding hyphae.
Once these and certain other microfeatures are mastered, and providing spores and basidia are present, any polypore can be identified from a mere fragment, because such features are constant, and do not change with habitat, or climate, as do most macrofeatures.
Let us now consider briefly how anatomical features may be used in delimiting genera. Out of the scores of generic names which have been proposed it has been necessary to select sufficient for an adequate classification. About 25 genera can be separated on features which are both constant and can be defined accurately. Some genera could be further subdivided on minor micro-features, but as yet there appears to be little advantage in maintaining a large number of genera for what is after all a relatively small family.
Most selected are well established names: but in the past have had no concise application. Consider. for example, the genus Fomes as used in its broad sense to embrace perennial species with round pores arranged in strata.
Though used by Fries in 1838 as a sectional name, Fomes was not employed in a generic sense until so used by Kickx in 1867. Under Fomes Kickx placed, in that order, F. salicinus, F. igniarius, F. fomentarius and F. lucidus. One is therefore the type species, but which? Some workers have arbitarily chosen F. igniarius, others, F. fomentarius without realizing that they are generically different plants. Two species possess brown, one hyaline hyphae; two possess trimitic hyphal systems with clamp connections; two dimitic hyphal systems without clamp connections. F. salicinus and F. igniarius possess brown hyphae, dimitic hyphal systems and are without clamp connections. They are therefore co-generic, and as the former has not been proposed as a type it may be disregarded further. F. fomentarius has brown hyphae and a trimitic hyphal system with chlamp connections in the generative hyphae. It is therefore not co-generic with F. igniarius. Upwards of 150 species of Fomes with brown hyphae and dimitic hyphal systems are known: whereas there are only about eight with brown hyphae and trimitic hyphal systems, as in F. fomentarius. Consequently stability in nomenclature would best be secured by regarding F. igniarius as the type species, since it also agrees most closely with the general interpretation of the genus. A generic name for F. fomentarius lies to hand in Elfvingiella which Murrill (1914) erected with it as type species. Fomes lucidus, on the other hand. has a trimitic hyphal system with hyaline hyphae and peculiar roughwalled spores, which may be termed ganodermous. It does not agree with the others as is evident, so must be placed under some other name. To it Karsten (1881) gave the name of Ganoderma. with G. lucidum as type species. So we have no less than three genera for the four species placed by Kickx under Fomes.
Two other species of world-wide distribution, usually placed under Fomes. now require consideration, namely F. applanatus and F. annosus. Both possess dimitic hyphal systems without clamp connections in the generative hyphae. But they are not Fomes, as defined above, nor co-generic with one another. For in F. applanatus skeletal hyphae are brown, freely branched in a peculiar manner—a condition found only in a few related species—and spores are ganodermous; whereas in F. annosus skeletal hyphae are hyaline. unbranched, amylaceous, and pores are smooth and hyaline. Karsten (1881, 1889) had provided generic names for both, with these species as types, namely Elfvingia for the former. Fomitopsis for the latter.
Thus the old genus “Fomes” consists of five genera, which may be defined accurately by the following characters:
|Hyphal system dimitic, without clamp connections.|
|Hyphae hyaline, spores smooth||Fomitopsis (F annosa)|
|Hvphae brown, spores smooth||Fomes (F. igmarius)|
|Hyphae brown, spores ganodermous||Elfcingia (E. applanta)|
|Hyphal system trimitic. generative hyphae with clamp connections.|
|Hyphae hyaline. spores ganodermous||Ganoderma (G. lucidum)|
|Hyphae brown spores smooth||Elfvingiella (E. fomentaria)|
(Certain other associated microfeatures are not listed.)
Friesian genera concerning which there has been uncertainty of interpretation, or were used to embrace species of several genera, can be defined similarly to include related species only. Polyporus, Lenzites and Daedalea have been used by most workers to contain species with hyaline or brown hyphae and monomitic. dimitic and trimitic hyphal systems. Polystictus, introduced by Fries in 1851
and regarded by most workers as a receptacle for thin species of Polyporus, has not been clearly defined, then or subsequently. And Trametes, erected by Fries in 1836, has remained a puzzle genus since. By aid of the features discussed it is possible to define them accurately and precisely, though as yet the position of Polystictus is doubtful. A rough guide to their diagnostic features is:
|Hyphae hyaline; with clamp connections or bridging hyphae.|
|Hyphal system monomitic or dimitic.|
|Pores round or oval.|
|Fructifications pileate||Polyporus Mich. ex Fr.|
|Fructifications resupinate||Poria (Pers.) Gray|
|Pores becoming irpiciform with a permanent poroid border||Irpex Fr.|
|Hyphal system trimitic, with clamp connections.|
|Pores round or oval||Coriolus Quel.|
|Pores lamellar or labrynthiform||Lenziles Fr.|
|Hyphal system monomitic, without clamp connections.|
|Setae absent from the hymenium||Coltricia Gray|
|Setae present in the hymenium||Inonolus Karst.|
|Hyphal system dimitic, without clamp connections.|
|Spores smooth||Hapalopilus Karst|
|Spores ganodermous||A mauroderma Murr.|
|Hyphal system trimitic, with clamp connections.|
|Pores round||Trametes Fr.|
|Pores lamellar or labrynthiform||Daedalea Pers. ex Fr.|
(A few genera, mainly of tropical distribution, have been excluded.)
In many of the old genera, difficulty arises in deciding the type species. Reasons are that early workers did not designate such, and as our concepts have changed because of the differential features employed, type species chosen arbitarily by later workers are not necessarily suitable for the purpose, as has been shown when discussing the type species for Fomes.
Anatomical features are equally useful in delimiting species, especially variable species, as to macrofeatures, not uncommon in tropical and subtropical regions; or resupinate plants placed under Poria or Fuscoporia. These latter are, incidentally, merely genera of convenience, the former containing resupinate forms of Polyporus, the latter of Fomes.
“Polyporus” occidentalis was found in Kew herbarium filed under five genera and twenty species; yet the microstructure of this common subtropical species shows it to be a Coriolus close indeed to our common C. hirsutus Daedalea trabea may develop fructifications with poroid. daedaloid, lamelloid or irpicioid hymenia. grow pileate or resupinate, range in colour from orange, through grey, ferruginous, to umber. In consequence it bears a formidable list of synonyms, because of these variable macrofeatures; yet has a microstructure so distinctive, that identification of each specimen is certain, no matter how diverse its gross morphology. A common Australasian species, “Polyporus” ochrolencus, is found in literature under Polyporus, Polystictus, Fomes, Trametes, and Ungulina, and bears upwards of twenty-five synonyms. Its microstructure shows it to be none of these genera, but a Fomitopsis with characteristic micro-features of that genus. One final example is provided in “Polyporus” schweinitzii, which has a world-wide distribution. Commonly treated as a Polyporus, Polystictus, or Fomes, it has also been described under Daedalea, Phaeolus, Cladomeris and Inodermus. Its microstructure is unmistakably that of Coltricia, as one section will show under a microscope.