The North American Species of Pholiota

Introduction

History

Fries (1821) established Tribe xxii, Pholiota of Agaricus, for many of the species here placed in the genus Pholiota. The history of the genus may be said to start from this publication since it is the official starting date for the nomenclature of agarics. Although the Greek word Pholiota means scale, some glabrous species such as Agaricus caperatus were admitted to the group. He included sixteen species, some of which (e.g., P. aurivella, P. adiposa, P. flammans, P. squarrosa and P. mutabilis) are still included.

In the same publication Fries erected a second group, Tribe xxv, Flammula, with fifteen species including Agaricus alnicola, astragalinus, spumosus, carbonarius, lubricus, lentus and others, species which are now included under Pholiota. Fries made a distinction between the two tribes on the basis of the character of the veil. In Pholiota he stated that the veil forms an annulus, membranous or radiate—floccose, and in Flammula it was said to be fugacious. In 1874, however, he characterized Pholiota as having an annulate partial veil, but then stated that Pholiota passes without distinct limits into Flammula.

Kummer (1871) was apparently the first to assign generic rank to these two Friesian tribes. Quélet (1886) proposed the genus Dryophila to encompass both tribes but then divided them into subgenera Pholiota and Flammula. Since Quélet's time, authors have varied between this concept and in maintaining both tribes as genera. Earle (1909) noting that the name Flammula is a homonym, having been used for a genus of phanerogams previously, proposed the name Visculus in place of it. Earle, in the same publication, recognized the genus Hypodendrum Paulet (1793). It will be noted that this name is "pre Friesian." Overholts (1932) used Paulet's name since he was following the old American Code at the time, and placed in the genus species with squarrose stipes. Those with glabrous or merely fibrillose stipes were placed under Pholiota. He excluded species of Flammula from his treatise.

In more recent times it has been observed that some of the species of the PholiotaFlammula group exhibit a germ pore broad enough to cause the spore apex to appear more or less truncate. Based chiefly on this character, Singer and Smith (1946b) proposed the genus Kuehneromyces for certain species in which the character was readily observable under ordinary magnifications with a compound microscope. More recently Singer (1957) proposed Pachylepyrium for certain species in which the spores are exceptionally heavily pigmented, smooth, and relatively thick-walled. Pleurocystidia were said to be lacking.

Despite the comment by Fries, upon which Quélet apparently acted, students of agarics since 1874 for the most part maintained Pholiota and Flammula as separate genera. Among these were some of the leading agaricologists of Europe: Ricken (1915), Rea (1922) and Lange (1935 –40). In North America Peck (1897) (1908), Atkinson (1900), Murrill (who used Karsten's name Gymnopilus in place of Flammula), Kauffman (1918, 1926), and Overholts (1927) accepted the same generic concepts. In 1953 Kuhner and Romagnesi followed Quélet (1886) in using the name Dryophila in that author's original concept.

Singer and Smith (1946, p. 264) expressed the opinion that the generic differences between Pholiota and Flammula in the sense of modern authors were too slight to justify maintaining both. In this respect they reiterated Quélet's (1886) opinion, but Singer (1951) sought to divide the group along lines other than originally indicated by Fries. This was a constructive move that has been followed by such recent authors as Moser (1955). Singer (1963) has given us the most detailed analysis of the whole group to date and it is the one which we have used as a point of departure for our study. Singer's work is of such importance that we include here the outline of his classification:

Pholiota

Subgenus Hemipholiota, type P. destruens

Sect. 1. Hemipholiota

Sect. 2. Sordidae, type Dryophila sordida

Sect. 3. Albocrenulatae, type P. albocrenulata

Sect. 4. Myxannulatae, type P. nameko

Subgenus Pholiota, type P. squarrosa

Sect. 5. Pholiota

Sect. 6. Adiposae, type P. adiposa

Sect. 7. Subflammantes, type P. subflammans

Subgenus Flammula, type Flammula flavida

Sect. 8. Flammula

Sect. 9. Lubricae, type P. lubrica

subsect. Polychrominae, type P. polychroa

subsect. Spumosinae, type P. spumosa

Sect. 10. Sericellae, type Agaricus scambus

Sect. 11. Privignae, type P. privigna

Sect. 12. Glutinigerae, type P. glutinigera

 

Our proposed classification follows by way of comparison:

Outline of Proposed Classification of Pholiota

 I. Subgenus Flavidula

Section Flavidula

Stirps Curvipes: P. curvipes, P. multifolia, P. subsulphurea, P. squamulosa

Stirps Aurea: P. aurea, P. fulvella, P. granulosa, P. erinaceella, P. pseudosiparia

Stirps Cinchonensis: P. cinchonensis

Stirps Curcuma: P. curcuma, P. murrillii, P. minutula, P. lactea, P. proximans, P. fagicola, P. subechinata

Stirps Corticola: P. corticola, P. cyathicola, P. pseudolimulata

Stirps Erinacea: P. erinacea

 

II. Subgenus Hygrotrama

Section Confragosae: P. anomala, P. punicea, P. canescens, P. confragosa

Section Hygrotrama: P. subangularis

 

III. Subgenus Hemipholiota

Section Sordidae

Stirps Discolor: P. striatula, P. mutans, P. discolor, P. brunnea, P. davidsonii, P. aurantioflava, P. gummosa

Stirps Serotina: P. serotina, P. kalmicola

Section Mutabiles

Stirps Mutabilis: P. mutabilis, P. caespitosa, P. tennessensis, P. veris

Stirps Marginella: P. marginella, P. albovirescens, P. deceptiva, P. umbilicata, P. albo-olivascens, P. bridgii

Stirps Obscura: P. obscura, P. nigripes, P. galerinoides, P. tahquamenonensis

Stirps Vernalis: P. pallida, P. subpapillata, P. conica, P. atripes, P. populicola, P. vernalis

Stirps Depauperata: P. depauperata

Section Hemipholiota

Stirps Destruens: P. destruens (and if distinct P. heteroclita and P. comosa)

Stirps Albocrenulata: P. albocrenulata

Stirps Olivaceodisca: P. olivaceodisca

Section Variabilisporae: P. variabilispora

 

IV. Subgenus Phaeonaematoloma

Section Albivelatae

Stirps Albivelata: P. albivelata, P. sipei

Stirps Cubensis: P. cubensis, P. duroides, P. johnsoniana

Section Phaeonaematoloma

Stirps Silvatica: P. silvatica, P. aberrans

Stirps Myosotis; P. myosotis, P. humidicola

Stirps Elongata: P. elongata, P. olympiana

Stirps Subochracea: P. subochracea, P. subcaerulea, P. burkei, P. subgelatinosa, P. parvula, P. pusilla, P. ornatula, P. melliodora, P. flavescens, P. lutescens, P. prolixa, P. californica, P. contorta

 

V. Subgenus Flammula

Section Flammula: P. alnicola, P. abieticola, P. subvelutina, P. flavida, P. oregonensis, P. malicola

VI. Subgenus Pholiota

Section Pholiota

Stirps Fulvosquamosa: P. fulvosquamosa

Stirps Schraderi: P. schraderi, P. sola, P. scabella

Stirps Squarrosa: P. squarrosa, P. kodiakensis

Section Adiposae

Stirps Squarrosoides: P. rigidipes, P. penningtoniana, P. terrestris, P. subcastanea, P. barrowsii, P. squarrosoides, P. romagnesiana, P. angustifolia

Stirps Adiposa: P. adiposa, P. flammans, P. aurivelloides, P. aurivella, P. lucifera, P. connata, P. hiemalis, P. subvelutipes, P. filamentosa, P. squarroso-adiposa, P. abietis, P. simulans, P. limonella, P. angustipes

 

VII. Subgenus Flammuloides

Section Flammuloides

Stirps Virgata: P. virgata, P. pseudograveolens

Stirps Olivaceophylla: P. olivaceophylla, P. castanea

Stirps Adirondackensis: P. adirondackensis, P. flavopallida, P. agglutinata

Stirps Condensa: P. condensa, P. subminor, P. bakerensis, P. iterata, P. sequoiae, P. alabamensis

Stirps Decorata: P. decorata, P. humii, P. vinaceo-brunnea, P. velaglutinosa, P. rubronigra

Stirps Ferruginea: P. ferruginea, P. sienna, P. ferrugineo-lutescens, P. hypholomoides, P. rufodisca

Stirps Occidentalis: P. abruptibulba, P. verna, P. rivulosa, P. occidentalis, P. fulvodisca, P. subfulva

Section Carbonicola

Stirps Carbonicola: P. carbonaria, P. fulvozonata, P. subsaponacea, P. luteobadia, P. highlandensis, P. molesta, P. brunnescens

Section Spumosae

Stirps Sphagnicola: P. sphagnicola, P. paludosella, P. sphagnophila, P. chromocystis

Stirps Graveolens: P. graveolens

Stirps Scamba: P. scamba, P. pulchella, P. calvini, P. tetonensis, P. pseudopulchella, P. totteni, P. gregariformis, P. scamboides, P. subdefossa

Stirps Subamara: P. subamara

Stirps Stratosa: P. stratosa

Stirps Spumosa: P. baptistii, P. spumosa, P. velata, P. vialis, P. piceina

Section Lubricae

Stirps Astragalina: P. astragalina

Stirps Fibrillosipes: P. coloradensis, P. sublubrica, P. armeniaca, P. subcarbonaria, P. fibrillosipes, P. luteola, P. spinulifera

Stirps Lubrica: P. lubrica, P. subtestacea, P. harenosa, P. gruberi

Stirps Polychroa: P. polychroa, P. avellaneifolia, P. trullisata, P. foedata, P. milleri, P. groenlandica

Stirps Crassipedes: P. biglowii, P. macrocystis, P. subflavida, P. crassipedes

Stirps Innocua: P. virescentifolia, P. brunneidisca, P. jalopensis, P. innocua, P. lurida

Stirps Lenta: P. fulviconica, P. acutoconica, P. squalida, P. lenta


Summarizing our concept, we place in Pholiota all species with smooth spores (with one possible exception, P. aurea), the spore deposit rusty-brown to yellow-brown, typically with at least a minute germ pore at the spore apex and at least an inner veil typically present as shown by fibrils on the stipe. In accordance with our detailed characterization of Pholiota we transfer to it all species of GymnopilusFlammula complex with smooth spores. Agrocybe and Conocybe featured by a cellular pileus cuticle and truncate spores are recognized by both Singer and ourselves as the core of the Bolbitiaceae. Many of these in which an annulus is present were at one time or another placed in Pholiota.

Purpose of the Present Study

Since previous taxonomic accounts of Pholiota and Flammula concerned with the North American species have not been based on a modern approach to a study of the basidiocarp, it was important to re-evaluate species concepts for even the so-called common species. Singer's treatment was a cross-sectional study of the genera and families of the Agaricales and did not purport to be even reasonably complete for this group in any region. Also, it was not concerned primarily with comparative studies of species in the larger groups.

In addition, while a cross-sectional study such as Singer's was of great value in aiding mycologists to gain perspective in relation to the genera of the agaricales, its very scope prevented it from dealing with the larger genera in detail. Before generic concepts can be established on anything like a stable foundation, the monographs must follow in the wake of Singer's cross sectional study. The present contribution should be regarded as a step in this direction.

It soon became evident in our study that the pholiotoid agarics of North America were far more numerous than we had expected. In fact it was only upon the completion of this work that we finally realized how much basic exploration remained to be done. Our description of over 75 previously undescribed species is evidence of the diversity of the flora, and we do not claim to have found all that occur here—that would be presumptuous indeed. It should be realized, but is not, apparently, in some quarters, that there is no region on the face of the earth that has been explored completely for any group of fungi. Fungi, unfortunately or fortunately, depending on your point of view, move around, so that one must always take the migration factor into account. Also, in spite of the collecting that has been done even in the restricted areas such as the British Isles where collecting has been done for years, there is no good representation of the British agaric flora in their herbaria—this now is being remedied by such workers as Dennis, Reid, Watling and others, but the situation reflects the changing thinking on the study of agarics over the last fifty years. If such a situation prevails in the British Isles, what about the United States? Here we have had to deal with a much larger more complicated flora with fewer people studying it. To the extent that these factors have operated in our country, we are just that much farther behind such areas as the British Isles and Scandinavia in the problem of a basic inventory of our species and in learning their relationships. In view of this the number of "new" species in this work needs no apology. If one is due it is for not having more than one lifetime in which to complete the work.

Our collecting procedures have been organized around a sampling process of working in the various forest associations of North America in the various climatic regions. We know from intensive collecting in selected areas such as the Great Smoky Mountains National Park, and the devastation left in the wake of logging operations in the Upper Peninsula of Michigan, that the only approach to a reasonably complete knowledge of our flora, especially as it pertains to wood-decay fungi in general, is to follow the fruiting of fungi in such areas from spring through fall regularly from the time the slash first starts to "produce" until it is reduced to humus. This involves working during unfavorable as well as (luring favorable seasons. Smith has made an attempt to do this, to the extent that time and facilities permitted, in the hardwood slashings near Emerson, Michigan in Chippewa County. It is only after attempting such a program that one can realize fully the futility of going into an area for a single season, and then thinking that the agaric flora has been "collected." Even after a good season, one obtains only a partial picture. One season, of course, is always better than none.

Our purpose here, we wish it clearly understood, is not to present the complete picture of Pholiota in North America, but to present a modern treatment of sufficiently broad scope to allow one interested to ascertain the identity of most of the collections he makes, and to help him recognize and understand the lines along which species are evolving, and where worthwhile opportunities for critical studies in culture can be made for further elucidation of complex species groups.

General Description of Text Figures

The drawings of the spores as reproduced are at an approximate magnification 1900 times. The details are shown somewhat schematically as it was difficult to work with a camera-lucida on details less than 0.3 μ in diameter. The drawings of cystidia are approximately X 1000 but for Pholiota macrocystis the magnification is approximately 600. In the cystidia it was not always possible to see the clamp at the crosswall because in the course of crushing the amount to bring the entire cell into full view it often broke at the cross wall. Sometimes the oblique septum of the clamp shows but more often than not it did not show simply because it was impossible to orient the cystidium to get a perfect medial optical section in the right plane to show it.

Acknowledgments

The aid rendered in this study by institutions and individuals has been indispensable.

Each of us has had valuable support of the National Science Foundation through a series of grants of funds.

Type specimens and other collections have been made available to us on loan. For these loans, we extend our grateful acknowledgment to the following persons and institutions:

Dr. Sten Ahlner, Curator, the Rijksmuseum, Stockholm; Mr. C. Bas; Curator, The Rijksherbarium, Leiden; Dr. Meinhard Moser, Bodenbiologisches Institut, Imst, Austria; Dr. G. Taylor, Director, Royal Botanic Gardens, Kew; Dr. R. Watling, Royal Botanic Garden, Edinburgh; Dr. H. E. Bigelow, University of Massachusetts, Amherst; Dr. Kenton L. Chambers, Oregon State University, Corvallis; Dr. James Kimbrough, Curator, The University of Florida; Dr. Patricio Ponce de Leon, Curator, The Chicago Natural History Museum, Chicago; Dr. Richard Korf, Curator, Cornell University, Department of Plant Pathology Herbarium; Dr. I. MacKenzie Lamb, The Farlow Herbarium, Harvard University; Dr. Clark T. Rogerson, Herbarium, The New York Botanical Garden, New York City; and Mr. Stanley Jay Smith, The Herbarium, New York State Museum, Albany. We also acknowledge the generosity of Dr. H. E. Bigelow, who made his photographs of Pholiota species available to us; and finally, our thanks to more than a score of devoted and zealous amateur mushroom hunters for the many interesting and new species they have communicated to us for study.

For courtesies extended in aid of field work we wish to acknowledge the wholehearted cooperation of the National Park service for the opportunity to collect in the Great Smoky Mts. National Park, Mt. Rainier National Park, the Olympic National Park and in the Rocky Mountains National Park. These areas play a most important role in preserving large tracts of our native forests for posterity and of course this means the preservation of all the elements of the forest biota. We wish also to acknowledge similar courtesies extended by the staff of the United States Forest Service, United States Department of Agriculture, from the forest superintendants as well as the rangers and other field personnel. Their help has been of inestimable value in locating quickly the type of site desired for a particular problem. Their patience with the working as well as recreating public is a model for all to follow. Beyond this, however, we wish to particularly acknowledge the facilities placed at the disposal of Smith and his party at the Priest River Experimental Forest, a unit of the Intermountain Forest and Range Experiment Station, Mr. Joseph Pechanec, Director. The location is ideal for the study of Pholiota, being as it is in the center of the Idaho white pine belt.

The University of Michigan Biological Station, Dr. A. H. Stockard, Director, was our most important central Great Lakes base of operations, but we also wish to acknowledge the opportunity granted Smith by the Huron Mountains Club and its Wildlife Foundation for the privilege of collecting in the virgin forests now dedicated by the Club as a natural area.