The biology and cultivation of edible mushrooms

1 Hymenium of a species of Morchella showing asci and paraph-yses; the ascus at the right shows the operculum at the apex, the spores have been discharged; 2 basidia of the type fou

THE BIOLOGY AND

The Chinese University of Hong Kong

Shatin, N T., Hong Kong

W A Hayes

Department of Biological Sciences

University of Aston

Birmingham, England

ACADEMIC PRESS New York San Francisco London 1978

A Subsidiary of Harcourt Brace Jovanovich, Publishers

A C A D E M I C P R E S S , I N C

I l l F i f t h Avenue, New Y o r k , New Y o r k 10003

United Kingdom Edition published by

A C A D E M I C P R E S S , I N C ( L O N D O N ) L T D

24/28 Oval Road, L o n d o n N W l 7DX

Library of Congress Cataloging in Publication Data

Main entry under title:

The Biology and cultivation of edible mushrooms

Includes bibliographies and index

1 Mushroom culture 2 Mushrooms, Edible

I Chang, Shu-ting, Date II Hayes, W A

SB353.B47 635\8 77-6591

ISBN 0 - 1 2 - 1 6 8 0 5 0 - 9

PRINTED IN T H E UNITED STATES O F AMERICA

List of Contributors

Numbers in parentheses indicate the pages on which the authors* contributions begin

J ANGELI-PAPA ( 5 3 ) , Station de Recherches sur les Champignons,

LN.-R.A., 33140 Pont de la Maye, France

IKUO ARITA (475), The Tottori Mycological Institute, Japan Kinoko Re­

search Centre Foundation, Tottori, Japan

S T CHANG (35, 5 7 3 ) , Department of Biology, The Chinese University

of Hong Kong, Shatin, N T., Hong Kong

P C CHEN ( 6 2 9 ) , Department of Plant Pathology and Entomology,

National Taiwan University, Taipei, Taiwan

S CHENG (605), Department of Horticulture, National Taiwan Uni­

versity, Taipei, Taiwan

KENNETH W COCHRAN ( 1 6 9 ) , Department of Epidemiology, School of

Public Health, and Department of Pharmacology, Medical School, University of Michigan; Ann Arbor, Michigan 48109

E L I V CRISAN* (137), Department of Food Science and Technology,

University of California, Davis, Cahfomia 95616

J R DELCAIRE (727), 8 Rue des Dardanelles, 75017 Paris, France

J DELMAS (251, 645, 699), Station de Recherches sur les Champignons,

I.N.R.A., Centre de Recherches de Bordeaux, Domaine de la Grande Ferrado, 33140 Pont de la Maye, France

R L EDWARDS (299), 2 Landway, Bearsted, Maidstone, Kent ME14 4 B D ,

England

G EGER (497), Institut fόr Pharmazeutische, Technologie der Universitδt

Marburg, D-3550 Marburg, West Germany

J E Y M E ( 5 3 ) , Universite de Bordeaux I, Laboratoire de Botanique,

33405 Talence, France

GERDA FRITSCHE (239, 3 7 1 ) , Proefstation voor de Champignoneultuur,

* Present address: 690 Alvarado Avenue, Apartment 13, Davis, Cahfomia 95616

XVI List of Contributors

Peelheideweg 1, Horst-America 5960-AA, Postbus 6042, The Nether­lands

G GRAMSS (423), 69 Jena-Winzerla, Grenzstrasse 28, German Demo­

cratic Republic

W A HAYES (191, 2 1 9 ) , School of Biological Sciences, The University

of Aston, Birmingham B4 7 E T , England

M S Ho ( 3 3 7 ) , Taiwan Provmcial Farmer's Association, Taichung, Taiwan

H H Hou (629), Department of Plant Pathology and Entomology, National Taiwan University, Taipei, Taiwan

TATSUZIRO ITO (461), Mushroom Research Institute of Japan, Kiryu,

Japan

S C JONG (119), Mycology Department, American Type Culture Col­

lection, Rockville, Maryland 20852

D S KIM (345), Department of Apphed Mycology and Mushrooms,

Institute of Agricultural Sciences, OflBce of Rural Development, Suweon, Japan

M KOMATSU (445), The Tottori Mycological Institute, Japan Kinoko

Research Centre Foundation, Tottori, Japan

R H KURTZMAN, JR (393), Western Regional Research Laboratory,

Agricultural Research Service, U.S Department of Agriculture, Berkeley, California 94710

CARLENE A RAPER (83, 365), The Biological Laboratories, Harvard Uni­

versity, Cambridge, Massachusetts 02138

ANNE SANDS (137), Division of Environmental Studies, University of

California, Davis, California 95616

ALEXANDER H SMITH ( 3 ) , University of Michigan Herbarium, North

University Building, Ann Arbor, Michigan 48109

K SZUDYGA (559), Research Institute of Vegetable Crops, 96-100

Skier-niewice, Poland

K TOKIMOTO (445), The Tottori Mycological Institute, Japan Kinoko

Research Centre Foundation, Tottori, Japan

Y TOMINAGA (683), Genetics Institute, Hiroshima Agricultural College,

Higashi Hiroshima City, 724, Japan

H TONOMURA (409), Mori Mushroom Research Institute, Kiryu, Japan

C C Tu (605), Department of Plant Pathology, Taiwan Agricultural Re­search Institute, Taipei, Taiwan

P J C VEDDER (377), Director Mushroom Growers Training Centre,

Westerholstraat 2, 5961 B J Horst ( L ) , Holland

F ZADRAZIL (521), Institut fόr Bodenbiologie, FAL, Bundesallee 50, 3300

Braunschweig, Federal Republic of Germany

At these congresses most attention has focused on the continuing re­

search on the growth and cultivation of Agaricus bisporus ("cultivated

mushroom," "champignon de couche," "champignon de Paris"), cultiva­

tion (on beds or couches of composted horse manure) of which began

in the vicinity of Paris about 1650

The early organizers of the congresses were almost exclusively involved

with this species However, it was gradually discovered that Agaricus

was not the only edible higher fungus being grown commercially At the International Mushroom Congress held in Amsterdam in 1965, Dr K Mori of Japan showed his film on the cultivation of several species of edible fungi in eastern Asia, which "opened the eyes" of the western

world The cultivation of Pleurotus ostreatus and of Stropharia annulata started independently in Eastern Europe shortly after this

rugoso-congress

Matsutake (Tricholoma matsutake = T caligatum) is the most popular

fungus in Japan; it has challenged Japanese researchers and growers for many years A symposium was held in 1964 in Kyoto to discuss modes

of cultivating this fungus However, even at present it still has to be col­lected in the woods and has not been cultivated artificially

The famous "truffle du Pιrigord" (Tuber mehnosporum) of France

and other truffle species from the countries around the Mediterranean are also highly valued fungi International congresses on the cultivation

xvii

xviii Foreword

of truffles were organized in 1968 in Italy and in 1971 in France, and

successful cultivation of these mycorrhizal fungi has been initiated

It was fortunate that the Ninth International Congress (1974) could

be held in eastern Asia (partly in Japan and partly in the Republic of

China) Field excursions enabled the participants to observe commercial

cultivation of various fungi During the East Asian gathering the name

of the international congresses was changed to "International Congress

on the Cultivation of Edible Fungi."

Mutual discussions among the participants of this 9th Congress re­

sulted in Dr S T Changes securing the cooperation of prominent re­

searchers and practical workers on mushrooms and other edible fungi to

write about their special fields of interest Their contributions comprise

this comprehensive volume

Books in the Japanese language by Tottori and Sakari Hisamune on

the cultivation of Lentinus, Flammulina, Volvariella, Pholiota, Pleurotus,

Agaricus, and Ganoderma are basically manuals for cultivating, their

language making them accessible to only a limited circle of readers This

volume, edited by Dr Chang and Dr W A Hayes, should reach a much

wider audience with a much greater variety of interests

The fungi dealt with in this book, which are presently under cultivation

or may be cultivated in the future, can tentatively be divided into the

following groups, according to their occurrence in nature

1 Fungi that grow on fresh or almost fresh plant residues: Lentinus,

Pleurotus, Flammulina, Auricularia, Pholiota, Tremella, Agrocybe,

Ganoderma, Coprinus

2 Fungi that grow on only little composted material: Volvariella,

Stropharia, Coprinus

3 Fungi that grow on well or very well composted material: Agaricus

4 Fungi that grow on soil and humus: Lepiota, Lepista, Morchella,

Gyromitra

5 Mycorrhizal fungi: Boletes, Cantharellus, Amanita, Tuber, Matsu­

take, Morchella, Lactarius

The coverage in each chapter varies in depth; for example, more ex­

tensive research has been done on Agaricus bisporus and Lentinus edodes

than on various other fungi Gradually more and more will be known

about the biology of other fungi It is my sincere hope that this book will

lead to new ideas and stimulate further research

P J Bels President of Society International Commission

on Mushroom Science January, 1976 Horst, Limburg, Holland

Preface

The word mushroom may mean different things in diflFerent books

and countries In this book edible mushrooms refer to both epigeous and hypogeous fruiting bodies of macroscopic fungi that are already commercially cultivated or grown in half-culture processes or potentially implanted under controlled conditions Mushrooms are occasionally de­scribed as all kinds of fungi (Thallophyta) that lack chlorophyll; but in this book we deal only with those mushrooms that are edible, i.e., usable

as food and in some manner grown commercially

Two motivating forces have been responsible for the compilation of this book The first is academic, which we believe is common to any attempt of this kind It is our zealous desire to combine the knowledge

of the biological nature of edible mushrooms with established methods

of practical application (cultivation) In so doing, the information on the subject of edible mushrooms made available by many biologists and researchers during recent years has been organized and summarized in

a manner readily understandable, and hence accessible, to any scientist

or layman This work is the product of the collaborative eflForts of a group of the most knowledgeable men in their respective fields, consisting

of 33 fungal specialists representing scholars from 11 diflFerent countries The second motivating force, more commanding than the one just considered, stems from the fact that edible mushrooms are rich in pro­teins, and thus constitute a valuable source of supplementary food (ac­cording to current statistics, worldwide mushroom production annually

is of the order of 700,000 to 900,000 metric tons) In fact, mushrooms have played an important role in the diet of many people for thousands

of years

That mushrooms can serve as food is not, itself, of major importance However, the way in which edible mushrooms can be grown greatly enhances their importance As this book shows, a great variety of cheap (some almost worthless) materials, e.g., agricultural wastes, industrial

XX Preface

wastes, and family wastes, can be successfully used as media for growing

the various edible mushrooms It is reahzed also that these cultivation

methods, which have already proved practical, may be just a beginning

More efficient and far cheaper means are certainly within the realm of

realization as more and more people become interested in mushroom

research With this rapidly expanding human population (at the current

rate of 2.1%, representing a rise of about 75 million people per year, or

200,000 daily), the possibility of using edible mushrooms to assist in

alleviating the worldwide food shortage should obviously be vigorously

explored

This book emphasizes both the academic (biology) and the applied

(cultivation) aspects of edible mushrooms The reason for this is simple

In practically every science there are always these two aspects to con­

sider—it is like the two faces of a coin, inseparable and yet distinct

Knowledge of one is bound to enhance that of the other The two are

invariably complementary to one another, and only by combining the

existing knowledge of both in the same treatise, as is done in this book,

can we hope to integrate the science of edible mushrooms to the fullest

extent, hopefully for the mutual benefit of the researchers, on the one

hand, and the growers, on the other This book, therefore, aims to bring

these two groups into closer touch with one another than ever before

It is an indisputable fact that a gap still exists beween the academic

fungal researchers and the commercial mushroom growers It is our hope

to integrate the knowledge of researchers and the advanced techniques

of the growers so that both will be mutually benefited We are convinced

that researchers should know the problems faced by growers and that

the growers, in turn, should understand some of the basic biological facts

about the mushrooms which they cultivate In this connection, one might

add a significant point Growers should bear in mind that climatic con­

ditions as well as economic situations vary from one locale to another in

various parts of the world, thus creating differences in availability of

materials for media, methods for producing these media, and possibly

the use of manual labor/machines, etc These variables are always present

in contrast to the "biology*' of any given species of mushroom, which is

more or less the same all over the world

This book is intended for anyone who is interested in edible mush­

rooms: the experienced mushroom specialist, seasoned commercial grow­

ers, biology students, or simply the layman

Our principal hope for this book is that it will encourage and stimulate

further research on all aspects of edible mushrooms, with special attention

directed toward discovering new edible species and improving both the

quality and yield of existing ones This should eventually lead to their

mass production accompanied by reduction in cost A number of require­

ments are needed to realize these hopes First, more extensive chemical

analysis should be carried out, subjecting the various components to

well-planned tests in an attempt to assay their nutritional values These data

are important since they can provide us with a basis for objectively eval­

uating any edible mushroom Second, there is a great need for experi­

ments aimed at producing mutations which will improve the productive

capacity and efficiency of growing methods as well as possibly increasing

food values These are important steps which should lead to a substantial

boost in the uses of edible mushrooms and their ultimate contribution

to mankind

Last, but not least, we look forward to the day when basic and applied

research on edible mushrooms commands financial support of similar

magnitude to that devoted to other crops The position we are taking is,

indeed, not difficult to justify At present, edible mushrooms have made

a positive contribution to the diet of millions of people Faced with the

prospect of a deteriorating food supply, should we not endeavor to launch

a program to increase the production of edible mushrooms? If this book

serves as a stimulus in hastening that day, then the efforts of all those

who contributed to it will not have been spent in vain

We have been greatly encouraged by the financial support from the

Asia Foundation for the preparation of this book We would like to ex­

press our appreciation to P J Bels for writing the Foreword and to the

many contributing authors Special thanks are due to R J Bandoni, Uni­

versity of British Columbia; K M Graham, University of Malaya; J W

Kimbrough, University of Florida; B C Lu, University of Guelph; L B

Thrower, Chinese University of Hong Kong; and L C Wu, University

of Wisconsin for reviewing some of the manuscripts We are also grateful

to Academic Press for publishing the book

S T Chang

W A Hayes

IV Edibihty and Poisonous Properties 25

V Family Agaricaceae Fries 26

A Type Genus: Agaricus Fries 26

Agaricus Fries , 26

B Type Species: Agaricus campestris Fries 26

VL Family Strophariaceae Singer & Smith 28

A Type Genus: Stropharia ( F r ) Quelet 28

VIL Family Pluteaceae Kotl & Pouzar 29

A Type Genus: Volvariella Speg 30

Volvariella Speg 30

B Type Species: Volvarielh argentina Speg 30

VIIL Family Tricholomataceae Roze 30

References 33

I INTRODUCTION

To understand the present grouping of diverse species in a single

volume such as this, one must keep in mind that the higher fungi are a

large and heterogeneous group, numbering in the thousands of species,

and that people all over the world, at one time or another have tried them

as a source of food Some of the experimentation on edibility, undoubtedly,

3

Copyright © 1978 by Academic Press, Inc

All rights of reproduction in anv form reserved

were disastrous and some highly successful It is logical to assume that in different regions different species were tried, and the technique of obtain­ing the desired ones was in a large measure the same as it is now: in spite

of our present degree of development of mushroom growing as an in­dustry, most of the species eaten are collected in the wild We assume that the first attempts at mushroom growing were made by some who observed that a desirable species was usually found around a straw stack

or a heap of cow manure, and they decided to enhance the habitat in one way or another to obtain larger yields Also, they no doubt transplanted samples from the original pile to new piles of substrate by way of in­creasing total production From such beginnings, as new knowledge was uncovered relative to the nature of the mushroom plant, it took only a step

to transfer this primitive industry into the laboratory and to concentrate on the species which could be made to produce mushrooms on a predictable regime At present these studies are being continued relative to bringing more species into the commercial trade and to obtaining optimum yields

at lowest possible cost In short, the cultivation of mushrooms on an inter­national basis does not appear to have a single point of origin nor was it limited to a single species Consequently, in such a work as this, one finds

an assemblage of species selected purely on the basis that at some time in the past it was found that their fruit bodies (the mushrooms) were edible and that their production could be programmed in one way or another

In order to establish a background for the discussion of each species treated here, it is proper to fit them into the system of classification cur­rently in use by mycologists, and which, by and large, is thought to indi­cate relationships based on descent from a common, remote ancestor (or ancestors) Such a scheme is termed a natural or phylogenetic arrange­ment In it species are considered closely related if they have in common

a large number of features found to be relatively stable in the population Since the sporocarp is composed of threads (hyphae) of microscopic size, many of the features can be determined only with the aid of a micro­scope Such features are termed microscopic characters Those which can

be observed with the naked eye or with the help of a hand lens are termed macroscopic or gross characters Both sets must be considered in postulat­ing the degree of relationship between any two populations In systematic studies any one of the various recognized units (as categories in a hierar­chy of categories) is termed a taxon (pi taxa) An order, a family, a species, and each subdivision of any of the above, is a taxon Since our current classification of the higher fungi is based on both micro- and macroscopic details, one must be familiar with the structural details of the fruit bodies and spores to understand it Currently, "chemicar char­acters are also used These involve both empirical tests for color changes

1 Morphology and Classification 5

II T H E ASCOMYCETES

The edible fungi under cultivation for the production of sporocarps all

fall into two major groups: Ascomycetes and Basidiomycetes Considering

the Ascomycetes first, much attention has been given to culturing (or try­

ing to culture) members of the Discomycetes and the related order

Tuber-ales (truffles) In the Discomycetes (Cup Fungi), attention has been

focused on the genus Morchella of the family Morchellaceae The

asco-carps in this family are more or less club-shaped and the upper part of

the club is pitted The club consists of a thin shell of tissue around a

hollow interior Thus, in spite of the size of the ascocarp, there is relatively

little substance to it The ascospores are produced in the asci which in

turn are arranged in an hymenium (Fig 1 ) , and are forcibly discharged

from the asci at maturity The discharge of many asci together often

produces a visible cloud of spore dust and this is accompanied by a slight

hissing sound In technical descriptions the stalk is referred to as a stipe

The fertile upper portion is the head even though the shape is not as a

rule globose The taxonomy of the species of Morchella is still in an un­

settled state One finds some authors recognizing many species and some

only about a half dozen The species most used in culture attempts is

Morchella esculenta Fries Uncertainty as to the concept of this species

still exists as is evident if one compares the illustrations which have ap­

peared in fairly recent times Although morels are easy to culture in the

laboratory from tissue or spores, so far attempts to fruit them on a com­

mercial regime have been unsuccessful Thus, in a sense, the group is

peripheral to the present work It is the group, however, receiving the

most attention relative to introducing another type of edible mushroom

to the world market It constitutes a great challenge to the

mushroom-growing industry

The second group of Ascomycetes, the truffles, belong to the Tuberales,

as previously stated The ascocarp of the truffle plant may be characterized

as a cup fungus in which the cup remains more or less closed, and the

caused by application of chemicals and the chemical analysis of the

basidiocarp

In keeping with the concept that our classification is based on relation­

ship by descent, we consider the characters of the reproductive structures

to be of paramount importance, and consequently those cells or tissues in

which nuclei fuse or undergo meiosis or are associated directly with this

process are the starting points in systematics, not only for fungi but for

living organisms generally

III T H E BASIDIOMYCETES

Among the Basidiomycetes which are used commercially for food are

some species of Auricularia and one of Tremella These will be considered

first, ahead of the main group, the Agaricales, because the fruiting bodies (basidiocarps) are more or less shapeless to saucerlike and are carti­laginous to jellylike in consistency These genera are now included in the

Phragmobasidiomycetidae (Ainsworth et ah, 1973), a group encompassing

three orders: Tremellales, Auriculariales and Septobasidiales The various types of basidia featured by this group are shown in Figures 2, 3, 7, and

interior becomes filled with folds and veins growing inward, more or less, from the shell (peridium) The fruiting bodies are usually referred to as

"tubers,'' no doubt because of the superficial resemblance to a small potato The term tuber in mycology is not used in the strict sense of the vascular plant taxonomist The ascocarps develop in the soil and rarely become exposed over the upper surface This pattern of fruiting, of course, makes them very difficult to find, and has long furnished a source of humor to collectors The spores, when mature, cannot be discharged into the air as in a morel, and it is assumed that other methods of dispersal have been evolved, such as dispersal by insects Evidence for the fact that the Tuberales are closely related to the Discomycetes, however, is found in the fact that in some species previously classed as Tuberales, the asci still discharge spores forcibly even though the ascocarp never becomes open as in a cup This can be demonstrated by breaking open an ascocarp at just the right stage of spore development A small puff of spores can be obtained, and an examination of the ascus under the micro­scope will show that the spores have been discharged in the usual man­ner of the operculate Discomycetes

There are a number of species of truffles which are commonly used as

food: Singer (1961) lists Tuber aestivum Vitt., Τ uncinatum Chatin, Γ mesentericum Vitt., Τ montanum Chatin, and Τ brummale Vitt A num­ ber of species of Tuber occur in North America, but the tuber flora of this

continent involves species mostly different from those harvested in France and Italy Gilkey (1939) recognized 17 species in North America, but none, to my knowledge, are currently of commercial importance The method of cultivation in France and Italy is based on the environmental approach Since the mycelium of the tuber lives in the soil and forms mycorrhiza with certain species of oak, the technique is to plant the proper species of oak in the right kind of soil in an area where truffles have been found, and let nature do the rest

1 Morphology and Classification 7

/

1 8 g

Figs 1-19 ( 1 ) Hymenium of a species of Morchella showing asci and

paraph-yses; the ascus at the right shows the operculum at the apex, the spores have been

discharged; ( 2 ) basidia of the type found in the Dacrymycetales (not treated in the

present work); ( 3 ) and ( 7 ) a basidium of the Tremellales (Fig 7, a cross sectional

view below the point of origin of the sterigmata); ( 4 ) an ellipsoid spore; ( 5 ) an

ovate spore; ( 6 ) a profile view of an inequilateral spore; ( 8 ) a basidium of the

Auriculariales; ( 9 ) a basidium of the Cantharellaceae; ( 1 0 ) and ( 1 1 ) basidia of the

Agaricales; ( 1 2 ) , ( 1 3 ) , and ( 1 4 ) a section of hymenium of the Agaricales showing:

(12) a basidiole; ( 1 3 ) a leptocystidium; and ( 1 4 ) a young basidiole; ( 1 5 ) a cutis

(of the pileus); ( 1 6 ) an ixocutis; ( 1 7 ) an hymeniform cuticle; (18) a cellular cuticle

in tangential section; ( 1 9 ) a trichoderm (pileus or stipe)

8 In Auricularia, the hymenium covers the smooth surface of the ba­

sidiocarp The interior (trama) is mostly of gelatinous hyphae, which

cause the fruit body to have a tough cartilaginous consistency Auricularia

polytricha (Mont.) Sacc, the common name for which is Mouh Leh in

the Orient, is both grown commercially and collected in the wild on a

commercial basis Singer (1961, p 171) pointed out that, for the above

reason, it was diflBcult to know the production figures for that part of the

In the family Agaricaceae, Singer (1962) included Clarkeinda, phyllum, Volvolepiota, Macrolepiota, Leucoagaricus, Leucocoprinus, Agaricus, Melanophyllum, and Cystoagaricus Shaffer (1975) recognizes

Chloro-the family Lepiotaceae for those genera in Chloro-the above listing which pre­

cede Agaricus In the following account the concept of the Agaricaceae proposed by ShaflFer is accepted Agaricus is the most important genus

from our standpoint

The members of the Agaricales, in whatever limits one considers the order, feature sporocarps showing great diversity in size, form, and con­sistency, sufliciently so that their features are important in taxonomy The basidia (Figs 10, 11) in this order are differentiated from the hyphae only by a basal septum, though the hyphal tip in the process of maturing may become elongate-clavate to short-clavate In some species the basidia

crop grown commercially The method of culture, again, is a modification

of the environmental approach in that the logs used are inoculated with the wood from naturally infected logs

Tremella fuciformis Berkeley is a jelly fungus described from a

lignico-lous substrate in South America, but is apparently much more widely distributed The basidiocarps are white to whitish in color, gelatinous in texture, and are folióse to variously convoluted in shape Because of its jellylike consistency there are natural restrictions on its use as food It must be sold, if fresh, in areas near the point of production Species of

Tremella generally dry down to "almost nothing" but can readily be

revived by soaking Drying, however, is the method used to preserve most

of the material of TremeUa fuciformis offered for sale

1 Morphology and Classification 9

bear only two spores, four are typical, and parthenogenic variants vdth

some one-spored basidia are known (Mycena, Smith, 1934)

The degree of diversity of the basidiocarps in this order depends to a

considerable extent on whose concept of the order one follows The range

of diversity encountered is from woody to leathery to tough to truly

fleshy to membranous or, in some, gelatinous Needless to say there are

more undesirable species than desirable ones for cultivation based on this

feature alone The families which contain a large number of fleshy species

are, in particular, the Agaricaceae, Lepiotaceae, Russulaceae, Boletaceae,

Cantharellaceae, Strophariaceae, Pluteaceae, and Tricholomataceae All

of these families contain poisonous as well as fine edible species

1 THE BASIDIOCARP

a The Stipe In the Agaricales sensu Singer, the basidiocarp basic for

the group (that type possessed by the most species) consists of a stipe

(stalk), lamellate hymenophore (lamellae or gills), and a pileus (cap) The

stipe is a sterile structure which elevates the hymenophore to a degree

sufiicient to allow most of the spores to fall free of the basidiocarp and

be carried to new locations by air currents Its structure varies with the

genus and species, but basically the hyphae, at least of the cortical region,

are more or less perpendicular in arrangement Binding hyphae are also

usually present In the Russulaceae the stipe features a peculiar structure

in many of the species in that long columns of inflated cells

("sphaero-cysts") are present These are also referred to as sphaerocytes (a more

accurate designation; see Kits Van Waveren, 1968) Connective hyphae

bind these masses of cells together In cross sections the columns appear as

rosettes of cells and are so called Small aggregations of inflated cells may

also be present, or inflated cells, in some instances, appear to be the

matrical hyphae (the chief hyphal constituent of the tissue) In species

of the order Agaricales having very thin stiff stipes, the center is often

hollow, the cortex then being formed of more or less thick-walled cells

packed tightly together Between these two types innumerable varia­

tions in hyphal structure are found among the various taxa The thicker,

fleshier stipes in general are less specialized in their organization than

the narrower, more rigid types If the stipe is truly fleshy (as in Boletus

eduUs), it is eminently edible, especially in the button state of the basidio­

carp—in fact it constitutes the bulk of the "mushroom" at this stage The

same is true for a thick stipe such as that shown for Cantharellus

subalbi-dus Smith & Morse (Smith, 1975) Both of these species would make

excellent products for the market if ways to produce the basidiocarps

in culture on schedule could be discovered

In the taxonomy of the order Agaricales, the stipe furnishes some

addi-tional characters of importance In some species it discolors markedly at the base first, with the change gradually progressing upward This char­acter is constant at the species level, but is less evident in basidiocarps developing in relatively dry weather The general pigmentation of the stipe is of some importance, but is rather variable Usually it is a lighter

or darker shade than the pileus It is not uncommon for the apex to be more or less consolorous, with the lamellae and the midportion the color

of the pileus Color changes as the result of injury to the tissue will be found in most species where such changes occur on the gills and pileus under the same circumstances These are taxonomically significant

The structure of the cuticle of the stipe furnishes a number of features' used in the taxonomy of the order The cuticle (outer layer of the cortex) may be composed simply of more or less longitudinally arranged, closely packed, smooth narrow hyphae with or without slightly thickened walls Such a stipe is described as "naked." In a large number of species, how­ever, projections develop from the cuticular hyphae, or ends of binding hyphae simply project outward If a combination of these structures is sufiiciently dense, the surface appears frosted when perfectly fresh This

is often best observed with a hand lens and is technically described as

pruinose If the projections become relatively long ( ± 5 0 μτη or more)

and are arranged in a dense turf, the surface appears velvety to pubescent

If strands of hyphae radiate from the base of the stipe, the latter is said

to be strigose In some species the base of the stipe is simply covered with a fluffy mycelium If the turf of hyphal ends consists of single cells differentiated morphologically from simple hyphal ends, the cells are termed caulocystidia Their characters are of value in taxonomy, but it must be remembered that caulocystidia are extremely variable in shape, size, and thickness of the wall depending on the part of the stipe from which a sample is taken If branching is noted, the pattern is also likely to

be significant Caulocystidia have been found to be taxonomically signif­

icant in a number of genera by various authors: see Xeromphalina (Miller, 1968) In Lactarius, however, a great amount of diversity occurs, but

in some groups in which caulocystidia are prominent (subgenus galus), great variation in morphology of these cells limits the taxonomic

Plintho-emphasis placed on them

A rather important taxonomic feature is the development of a gelatiniz­ing caulocuticle, or of slime-producing caulocystidia or hyphal ends ar­ranged in a turf (an ixotrichodermium Fig 2 4 ) A stipe with one of the above conditions is slimy or sticky to the touch in perfectly fresh speci­mens The slime, however, may soon dry leaving the stipe surface shiny or

"varnished" and dry to the touch The slime layers, however, can be demonstrated under the microscope from such specimens because of the

1 Morphology and Classification 11

difFerence in the refraction of Hght through the reconstituted slime as

compared with the mounting medium Viscid to slimy stipes occur in

very small to very large basidiocarps (compare Mycena rorida with

Lactarius trivialis F r ) The feature appears to have originated inde­

pendently in a number of diiferent genera in diiferent families

The stipe is often decorated by the remains of veil tissue A problem

develops, however, when the veil tissue becomes intergrown with the

stipe

In most species the stipe is attached to the pileus centrally, but in

some it is off center (eccentric) In others, the pileus is not circular in

outline but at one side narrows to a stipelike point of attachment to the

substratum If this condition prevails, the stipe is said to be lateral (the

margin of the pileus is interrupted at this point), and in the words of some

older descriptions the pileus is "not marginate behind." The reduction of

the stipe reaches its end point in the sessile basidiocarp, i.e., stipe is lack­

ing and the pileus is attached directly to the substratum

The sessile condition is common among the pileate polypores but less

frequent among the fleshy agarics Also, it will be noted in some species

such as Pleurotus ostreatus, if the pileus forms on the side of an upright

tree trunk or other upright support, it will nearly always be sessile If a

tree has been cut off close to the ground and P ostreatus fruits on the flat

surface of the stump, a stipe will often be formed and, indeed, it may be

centrally attached I have observed this many times In other words,

within a single species we may have the stipe central, eccentric, lateral,

or wanting Great variability is encountered in some species relative to

the position of the stipe or even its presence; the extent of such variability

must be studied for each species to ascertain its taxonomic significance in

that taxon It appears at first glance that the loss of the stipe is a result of

the fungus forming its fruit bodies on a hard surface which then serves as

the support for the pileus with its attached hymenium It is true, however,

that sessile or nearly sessile basidiocarps may occur on clods of earth

(Rhodophyllus hyssisedus) or on moss clumps (Leptotus, some species)

Observations in the field indicate that the presence, position, or absence

of the stipe is generally genetically controlled, but that in some taxa the

control is not rigid Observations on numerous families lead to the con­

clusion that the tendency of the stipe to become reduced or obliterated

originated independently in many families in this order

b The Pileus The pileus is formed as a lateral expansion of the apex

of the stipe An example of how this might have happened in the course

of evolution can be seen if illustrations of species of Clavariadelphus are

compared with species of Cantharellus Within the order Agaricales,

however, evolution has gone so far as to produce a pileus readily separa­

ble from the stipe (see Agaricus and the species of the Pluteaceae) It is

significant that, in these groups, the lamellae are not attached to the stipe

Since in Clavariadelphus the hymenium covers the surface of the club, as

the apex of the club expanded laterally, the hymenium continued to de­velop and covers the underside of the lateral extension As the under-surface (the hymenial surface) developed wrinkles and folds, we have the basis for the formation of either gills or pores or both These configura­

tions of the hymenophore are found in the genus Cantharellus Detailed analysis of the anatomical features of the basidiocarp in Clavariadelphus and Cantharellus lends support to the suggested manner of origin of the

pileus and hymenophore

For purposes of our discussion the pileus can be divided into two re­gions: the context and the cuticle or covering layer The structure of the pileus context varies somewhat in the diiferent families of the order, but

is truly distinctive only in the Russulaceae Here we have a tissue com­posed of groups of sphaerocytes seemingly imbedded in a matrix of con­nective hyphae Variation, however, occurs in the number of sphaerocytes

present and in their disposition In some species of Russula, the context of

the pileus in tangential sections appears to be mostly sphaerocytes at

maturity, whereas in some Lactarii these cells are found almost entirely

in nests (rosettes), and the latter occur sparsely in more or less of a dis­tinct region below the cuticle In other families such as the Coprinaceae, which can hardly be considered phylogenetically close to the Russulaceae, large numbers of inflated cells are present but do not extend into the stipe

in the manner described for the Russulaceae, nor are they arranged in rosettes in the pileus Cell inflation, to some degree, is the rule in the matrical hyphae of the pilei of the fleshy Agaricales The inflated cells vary greatly in size and shape, or the hyphal cells may enlarge evenly in both length and width, thus maintaining the basic tubular (Fig 3 0 ) shape

to some degree This process contributes to the rapid enlargement of the pileus

The hyphae are commonly radially arranged, extending, as one might expect, from the stipe toward the pileus margin In many species, how­ever, they are more or less tangled at right angles to the radius of the cap,

or mixtures of all three conditions occur Also, the arrangement often becomes more intermixed as the pileus matures and ages

In some species the context hyphae may be gelatinized, or only a layer

of gelatinized hyphae may be present Such species usually have a pliant

to rubbery texture when fresh Such hyphae or hyphal layers can be

recognized with the microscope on sections mounted in 2,5% KOH They

are distinctly translucent as compared to the nongelatinized tissue The

1 Morphology and Classification 13

polypores, which are beyond the scope of this chapter, often have a

woody context, and various hyphal systems can be recognized in the

various species

The cuticle of the pileus is defined as the differentiated layers or zones

forming the covering of the pileus as contrasted to the trama (the body

of the context) The cuticle shows considerable diversity in its organiza­

tion and these differences are taxonomically significant A cutis is a cuticle

composed of more or less radial nongelatinized, narrow (2-3 μχη wide)

hyphae in a layer two or more hyphae deep This degree of differentiation

is derived from a condition in which no hyphal differentiation is present

to separate the context from a cutis Both the undifferentiated condition of

the cuticular region and the simple cutis are of widespread occurrence in

the Agaricales As one might expect, it is often difficult to distinguish be­

tween them In the simple cutis the hyphae have long narrow tubular

cells with smooth thin walls

One of the common types derived from the simple cutis is the ixocutis

(Fig 16) In it slime is excreted by the cuticular hyphae or the hyphal

walls themselves gelatinize to produce slime which readily takes up water

with the result that an ixocutis is usually thicker than a cutis and the hy­

phae are spread further apart Such a layer is sticky or slimy to the touch

when fresh Both types of slime formation, apparently, occur in the

cuticle of many species It is commonly known that in an ixocutis a few

of the hyphal ends may be ascending to upright If these are numerous

enough to form a turf or palisade, if the elements are septate, and if the

layer contains slime, the structure is termed an ixotrichodermium (Fig

2 4 ) A high degree of development of such a cuticle is found in many

species of Lactarius (e.g., L mucidus) in which the elements are long,

very narrow ( 1 - 3 μτη), often branched, and hyaline as revived If no

slime is present in such a layer it is termed simply a trichodermium (Fig

19) In the latter, however, one usually finds that the cells are broader,

and the end cell of the element often has distinctive markings and/or

shapes (see the Boletaceae; Smith and Thiers, 1971)

In some members of the order, the turf layer (which may also be re­

ferred to as an epicuticle) arises from a differentiated basal layer or

sub-cuticle A third region, the hypoderm, is discernible in some species The

differentiation in the subcuticle may consist of numerous short cells being

formed (by the formation of secondarily formed cross walls), or it may be

in the form of a simple cutis In some species the short cells may inflate

considerably giving the layer a cellular appearance in tangential sections

of the pileus

In a trichodermium as well as an ixotrichodermium, the turf elements

are mostly multicellular (two or more cells) If a turf is made up (roughly)

of =b* upright single cells, it is termed a hymeniform cuticle (Fig 1 7 )

In this type the cells may become quite enlarged and versiform, but the basic unit is the clávate cell The enlarged apices of these cells form the surface of the pileus In many species "hairs" or otherwise diverse cells may project from the layer These are termed pileocystidia (Section III, A,2,b) If the cells forming the cuticle become globose or roughly iso-diametric, we have the cellular cuticle (Fig 1 8 ) This type can originate from the hymeniform type, or from cell inflation in the subcuticle and in

Psathijrella (Coprinaceae) both types may contribute to cuticle forma­

tion in a single species A cellular cuticle may also originate from the cells

of trichodermial elements having at least the lower cells enlarging greatly and becoming packed closely together from mutual pressure, as in sub­

genus Plinthogalus of Lactarius

In summary, the major types of pilear cuticle in the fleshy Agaricales fall into two major types: dry and slimy to viscid In the dry type we have a simple cutis, a cellular to hymeniform cuticle, and a trichodermium

In the slimy category the main types are an ixocutis, and an ixotricho­dermium It is important to bear in mind that all these types intergrade: species with a hymeniform cuticle may have a somewhat viscid pileus from the secretion of a slight amount of slime by the cuticular elements (see the Bolbitiaceae) The simple cutis can be well developed or poorly developed, and an ixocutis may be composed of a thick layer of hyphae very much interwoven and widely spaced as seen in sections under the microscope Cuticular types in the Agaricales are repeated many times in the various families, often with slight variations In studying them, basidio­carps just reaching maturity should be used In g^eneral, my impression is that the phylogenetic value of the various structures is often limited to a single genus, but at the infrageneric level they furnish fundamental char­acters to the systematist

c The Hymenophore Within the order Agaricales sensu Shaffer (1975)

many types of hymenophore are found with four major types distinguish­ing large groups of species The lamellate type (with gills) is featured by the Agaricales in the narrower sense of the order, but it is not the only type occurring The polypores feature the poroid condition in combination with a woody to tough consistency, and the Cantharellaceae feature a smooth to wrinkled hymenophore The Hydnaceae have the basidia borne

on the covering spines which are oriented downward Some in this family have a fleshy consistency As indicated previously, the hymenophore de-

* ± , More or less

1 Morphology and Classification 15

velops on the outer surface of the basidiocarp if one is differentiated It

occurs on the underside of the pileus (if one is present), and may be in

the form of gills, pores, spines, or a smooth to wrinkled surface The

hymenophore is positively geotropic as one can demonstrate rather

readily: the basidiocarp, if laid on its side, will change position by curva­

ture in the stipe to orient the hymenophore in the vertical position for

spore discharge There are occasions when one finds a basidiocarp with

abnormal hymenial development, such as when the pileus fails to develop

and the lamellae develop into a folióse type of arrangement from the

apex of the stipe This is a feature that may sometimes be observed in the

genus Lacearía (Tricholomataceae)

In the fleshy Agaricales, the hymenium is produced on thin plates

termed lamellae (gills) These extend from the stipe to the cap margin

Between the complete gills, one to several tiers of shorter ones are often

present which collectively are termed lamellulae Often, between the gills,

especially if the latter are fairly widely spaced, one finds veins developing

which cross from one gill to the next one If the veins develop to the same

width as the gills, wide pores are produced In the Agaricales in the family

Boletaceae, genus Suillus, this condition occurs in a number of species

In the Boletaceae are placed some species with distinct gills, some with

wide pores as indicated above, and some with very minute pores The

genus Boletinus, now not recognized by many investigators as distinct

from Suillus, contained species with the intermediate type of hymeno­

phore This type is termed "boletinoid." This type is also found in Paxillus

but in a less developed state The Boletaceae is the one well-known family

in the fleshy Agaricales in which the poroid hymenophore is found in a

highly developed form The tubes are often long (up to 1.5 to 2 cm) and

very narrow, often 3-4 per mm

The fleshy Agaricales with a smooth wrinkled hymenium fall into two

groups The first type presumably has come from ancestors having gills,

but because of the small size of the basidiocarp ( ? ) often has no gill

formation In the second type, which is thought by some to be primitive

in the evolutionary sense, the basidiocarps are typically larger and have

the outer surface smooth to wrinkled The gilled group is thought to have

had its origins here in the Clavariadelphus—Cantharellus—type of basidio­

carp The survival rate for species with gills is presumed to be much

greater than for those with a smooth hymenium because of the larger

number of spores produced, but this is not the whole picture, for the

primitive type presumably has survived along with the variants develop­

ing from it Generalizations do not necessarily apply to particular pairs of

species

The gilled members of the Agaricales constitute the bulk of the order, and are divided into numerous families Thus it is logical to discuss gill structure at this point

d Gill Structure A typical gill, for instance, of a Clitocybe

(Tricholo-mataceae) in cross section (Fig 20) consists of the hyphae which grow downward from the context of the pileus in narrow zones or lines, thus determining the spacing of the gills The hyphae mostly grow downward, but do become interwoven to form a tissue termed the lamellar (gill) trama which is a continuation of the pileus trama (context) The hyphae nearest the surface on each side grow out into a compact zone of narrow much-branched hyphae which then give rise to the basidia and basidioles The latter form a layer or palisade known as the hymenium, which is the surface-covering of each face of the gill The term subhymenium is given

to the usually compact interwoven layer giving rise to the hymenium The hyphal arrangement in the trama as described above is termed interwoven (Fig 20) The term is self-explanatory This is the basic hyphal arrange­ment in the gill trama of the fleshy Agaricales The ornamentation of the hyphae, if such is present, is considered independently of the hyphal arrangement The hyphae may be smooth, incrusted, thin-walled, thick-walled, hyaline, colored, or, at the cross walls, some may characteristically have a clamp connection and some may not The cells may remain narrow and tubular or become variously inflated In many species gleopleurous hyphae are present along with the matrical type If a latex is present, as

in Mycena haematopus, the latex-bearing hyphae are termed lactifers

This latex and the deposits which occur in the gleopleurous hyphae may represent waste products, but there is some question in my mind as to how many names we should use to designate them

Returning to the type or pattern of hyphal arrangement, in some species of the Hygrophoraceae we find a type termed "paralleF (Fig 21), which is a close approximation of the pattern described by the term The main hyphae extend down from the pileus trama roughly parallel to one another This pattern occurs to some extent in other families, but here the picture is often rather one of intergrading types The Hygrophoraceae are

a good family for the study of hyphal arrangement in the gill trama be­cause the major types, parallel, interwoven, and divergent, all occur there

In Hygrophorus pratensis the basic interwoven type is found, and in Hygrophorus camarophyllus the divergent type (Fig 22) is found These

three arrangements of the tramal hyphae have been used by some investi­

gators as single characters to define three genera: Hygrophorus, Camaro­ phyllus (see Singer, 1975), and Hygrocyhe

In the divergent type, illustrated by Hygrophorus, the hyphae grow

1 Morphology and Classification 17

30 Figs 20-30 ( 2 0 ) - ( 2 3 ) Diagrammatic cross sections of gills in Agaricales show^ ing four major types: (20) interwoven hyphae forming the trama; (21) parallel hyphae; (22) divergent hyphae from a central strand; ( 2 3 ) convergent hyphal cells

of the Pluteaceae The dotted area indicates the region of the subhymenium, and the horizontal hatching shown in Fig 1 represents the hymenium which covers both gill faces in all four figures (24) an ixotrichoderm (pileus or stipe); (25a-b) formation

of a clamp connection—(25c-f) show diflerent degrees of looping by the clamp branch

—both types of clamps (looping and nonlooping may be found on a single basidiocarp depending on the species); (26) a seta (with brown thickened wall); (27) a macro-

cystidium (type found in hymenium of some Lactarii); ( 2 8 ) a pseudocystidium of the

Russulaceae with a basidium for comparison; (29) two views (face and profile) of a

single spore of a Coprinus species; (30a-d) a schematic hypha (lacking clamps)

showing types of wall adhesions: ( a ) incrustations platelike to collarlike; ( b ) spirally arranged incrustations; ( c ) extraneous granules colored or hyaline on the hyphal wall and in some cases readily removed mechanically or soluble in reagents; (d) a smooth wall

downward from the pileus trama and, at the area between the hymenium and the central column, they diverge outward toward the hymenium to produce the subhymenium This is readily demonstrated on fresh, slightly immature basidiocarps When sections of mature or old gills are revived, however, these hyphae do not always assume their original arrangement and usually appear parallel to slightly interwoven The divergent type of

gill trama is found in the Hygrophoraceae, Tricholomataceae, Boletaceae, and to some extent in the Gomphidiaceae, and is rare in some others In

the Tricholomataceae in some species of Catathelasma it can be demon­

strated convincingly only in young specimens In mature specimens the trama appears subparallel-interwoven (or "regular" in the terminology of

some investigators) In some species of Amanita the divergence of the

hyphae is difficult to discern because of the enlargement of all the cells

In this genus, also, it appears that the "diverging" elements are lateral outgrowths of the hyphae of the central column As indicated, the diver­gent pattern of hyphal arrangement has apparently originated more than once in the Agaricales

A major pattern of cell arrangement in the gill trama of importance to the present work is the inverse or convergent (Fig 23) pattern The Chinese Mushroom (Chang, 1972), cultivated so extensively in the Orient, features it In this type, which is a major character in the circumscription

of the Pluteaceae, the area of the trama next to the subhymenium or in­cluding this tissue consists of interwoven ± narrow hyphae which give rise to large cystidiumlike cells which become oriented slantwise from the interwoven layer interiorly and with the end of the cystidium toward the gill edge Roughly, the impression of the letter V is obtained if ± paired cells are viewed These have been referred to as endocystidia by Walker

(1919, 1920) This type of gill trama bears no resemblance to the type or the Hygrophorus-type, and for this reason most investigators pre­

Amanita-fer to recognize a separate family, now designated the Pluteaceae Kotl & Pouzar

Cell inflation is a common feature of the hyphae of the gill trama in some if not all families, but especially so in the Coprinaceae In the Tricholomataceae all conditions are found, from narrow hyphae with

elongate cells to those with greatly inflated cells as in Mycena In the small basidiocarps, such as in many Collybia and Marasmius species, the

degree of inflation is often not significant To judge the degree of cell inflation and the form it takes, one must use mature basidiocarps

2 HYPHAL SYSTEMS AND HYPHAL CHARACTERS

Hyphal systems in the sense of the current studies on polypores do not attain the prominence in agaric classification that one might expect In­stead, we study tissues, either sharply defined or rather generalized These have already been reviewed: those of the pileus, lamellae, and stipe One hyphal feature needs discussion: the clamp connection (Fig 25, a,b) The clamp connection is a branch which when present is associated with the mitotic divisions of the dikaryon (the two haploid nuclei in a cell having opposite "sex potential") to the extent that it furnishes a path for the mi-

1 Morphology and Classification 19

gration of one of the nuclei to the cell which has just become the penulti­

mate cell of the hyphal tip The branch (clamp) starts to grow out from

the hypha just distal to the point where the cross wall is going to form and

bends backward as a short tube ± parallel to the original hypha After the

nuclear divisions have taken place (one nucleus dividing in such a posi­

tion that when the telophase stage is reached and the cross wall formed)

one of the daughter nuclei is located on each side of the new cross wall

The second nucleus divides in such a position that one daughter nucleus

enters the branch (clamp) and the other remains in the tip cell of the

hypha The hyphal branch now fuses with the penultimate cell of the

hypha at a point behind the new cross wall, a pore is formed in its wall,

and the nucleus in the branch migrates into what is now the penultimate

cell The clamp connection proper is the short lateral branch now visible

as a hump on the hyphal wall bridging the new cross wall (Fig 25, a - f )

Some agaricologists rightly insist on regarding clamp connections as a

feature independent of other taxonomic features but (depending on the

species) at times linked in various combinations to them They regard it

as wrong to define a cross wall as a "nodose septum'' when the branch

which forms the clamp is not in contact in any way with the cross wall

It has now been amply demonstrated that as a taxonomic feature clamps

are as variable as other characters from species to species In some

species they are absent, at least on the hyphae of the basidiocarp In some

they may be present on the connective (narrow) hyphae and not present

elsewhere In Pluteus they may be absent, rare, present on about half of

the septa of the cuticular hyphae of the pileus, or present at nearly every

septum (as in Pluteus salicinus and variants of Pluteus cervinus) The

situation as it has developed indicates that the presence or absence of

clamp connections is important at the species level but that genera should

not be proposed with the presence or absence of clamps as the definitive

character

In the trama of the pileus and lamellae there is usually one type of

hypha which is the foundation type, referred to here as matrical hyphae

(those forming the matrix of a tissue) Interspersed among these one will

usually find hyphae with a globular or amorphous content and, if a latex

is present, these are termed lactifers If no latex is present, various names

such as oleiferous hyphae have been applied to them The value of a

name (or which name to use) calls for a conservative point of view, espe­

cially when one sometimes finds such a hypha producing a basidium with

spores on it (see Smith and Thiers, 1971, p 11) Apparently in the metab­

olism of the basidiocarps, waste products are produced and must be de­

posited somewhere, and since they are formed in hyphae, that is where

they are finally deposited

a The H ymenium. The primary functional tissue of the gill is thehymenium-the palisade of hyphal end cells and hyphal branches (basidiaand basidioles) In this layer, in some taxa, scattered cells of variousshapes (the cystidia) also occur (Fig 13) The basidium (Figs 9, 10, 11,

12, and 14) in the Agaricales is a simple end cell of a hypha or hyphalbranch in which the two nuclei fuse thus forming a fusion nucleus withthe 2nnumber of chromosomes Following the fusion, this nucleus under-goes two or three divisions depending on the species, thus forming four oreight nuclei each with the n number of chromosomes These products ofmeiosis (reduction division) then migrate into the spores which are form-ing on spicules originating from the apical region of the basidium Thespicules (sterigmata) are typically four in number, but six or even eightare not uncommon in the family Cantharellaceae If eight nuclei areformed by the reduction divisions, frequently four remain in the basidiumand one migrates into each of the four spores that are formed It is theprocess of fusion of nuclei with the following reduction divisions that dis-tinguish the basidium from other hyphal end cells of the basidiocarp.Since an "immature" basidium does not show sterigmata, in the currentterminology of the hymenial elements we refer to it as a basidiole (Figs

12 and 14) It is these structures that are observed more frequently onsections under the microscope than the basidia (with sterigmata) Al-though the typical number of spores borne on a basidium is four, and inthe Cantharellaceae sometimes more (six to eight), one-, two-, and three-spored basidia are known, e.g., in Mycena, and, less frequently, in othergenera Some of these basidia have been studied cytologically and werefound to be parthenogenetic (Mycena megaspora; Smith, 1934) In otherwords, only one nucleus was present in the young basidium so no fusion

of nuclei could take place For many species, however, two-spored variantsoccur in which the nuclear cycle is normal and the two-spored conditionconstant (Agaricus bisporus). In extensive studies of collections of theTricholomataceae and other families, a mount mainly showing four-spored basidia will show some two-spored ones also The meaning of this

is not entirely clear In Lactariusit is at times difficult to decide whether

a cell is going to be a one-spored basidium or a cystidium It is important

to the mushroom grower trying to improve strains of species for the trade

to know the cytology of the material with which he is working

The shape of the basidium varies little within the order Typically it isclavate to elongate-clavate [the latter in the Cantharellaceae (Fig 9)],but it varies greatly in size from genus to genus In the Cortinariaceae inparticular (see Cortinarius and Pholiota) some species show a coloredcontent in at least a few basidia when these are revived in weak KOH

1 Morphology and Classification 21

In Lyophyllum of the Tricholomataceae the basidia contain siderophilous

granules (formerly termed carminophilous) which are used as an im­

portant generic character

Admittedly, a basidiole is a basidium which has not yet produced

sterigmata As one views a section of the hymenium, however, especially

one of a basidiocarp past maturity, one cannot help being impressed by

the number of basidioles which, apparently, will never produce sterigmata

and spores At the basidiole stage one cannot accurately predict which of

the cells will produce spores and which will not It is evident that the

basidioles perform two functions: one by developing into basidia, and the

other by forming a foundation for support of those which do become

basidia The supporting function is clearly evident in many taxa of the

Coprinaceae in which the morphological difference between the founda­

tion cells (modified basidioles) and basidia is clearly evident The ba­

sidioles in Coprinus inflate markedly and appear in sections of a mature

portion of the hymenium as enlarged ± isodiametric cells in contrast to

the clávate narrower, often long, pedicellate basidia The term

*T)rachy-basidiole" is used by some for such morphologically differentiated basid­

ioles These cells should not be classed as a type of cystidium since they

are the foundation element of the hymenium Cystidia occur haphazardly

over the surfaces of the basidiocarp, and are often present in a Coprinus

hymenium showing well-developed brachybasidioles The Coprinaceae

and Bolbitiaceae are the two families exhibiting the best development of

brachyb asidioles

b The Cystidia These cells occur scattered through the hymenium,

and are of various sizes, shapes, types of content, wall thickenings, in­

crustations and, at times, exhibit branching Cystidia are classified in two

ways: one for convenience, and one based on the features of the cell

itself Since cystidia can occur on any surface of the basidiocarp, and

often vary in their features depending on their position, the following

classification based on their position is used This is the classification of

convenience

1 Pleurocystidia—those on the faces of the lamellae

2 Cheilocystidia—those on the edge of the lamellae

3 Pileocystidia-found on the surface of the pileus, typically

scattered

4 Caulocystidia-on the surface of the stipe They may vary in shape

and size as taken from near the apex as compared to those found near

the base of the stipe

5 Endocystidia—specialized cells borne in the trama of the gills or pileus These are more commonly encountered in the polypores, but are also found in the Pluteaceae

Let us now consider the cystidium in relation to a classification based

on its morphology and chemical characters Most hymenial cystidia origi­nate from the subhymenium in the manner of basidioles, but in some

species they may originate from the gill trama (see Pluteus cervinus and

variants) They occur scattered over the tissue concerned Nearly all genera having species with pleurocystidia also have species in which these

structures are absent In Agaricus few species have them and the com­

monest type, according to my experience, appears to be a clávate to vesiculose, hyaline, thin-walled, smooth cell larger than the basidia or basidioles These originate from the subhymenium as do the basidia, and one is inclined to think of them as modified basidioles It would be in­teresting to study the genetics governing which cells shall differentiate in this manner, but the approach is difficult for obvious reasons

A slightly more highly differentiated cystidium is the flask-shaped to fusoid-ventricose type (see Fig 13) These are the common type through­

out Psathyrella, many genera of the Tricholomataceae, and in the

Vol-variaceae, but are by no means limited to these families Both the above types occur in a great diversity of shapes and come under the major head­ing of leptocystidia

The term "lamprocystidium" applies to a thick-walled cell, the wall being hyaline If the wall is appreciably colored the term seta (Fig 26) is applied, especially if the cystidium is long, narrow, and pointed In some, however, the wall is very sHghtly colored so that there is no clear line of demarcation between the two types In the technical literature of the day, rather elaborate classifications of cystidial types have been made, but there is still no substitute, in agaric systematics, for describing these cells

in detail for each species

In gloeocystidia (including chrysocystidia; see Smith, 1951) the content

of the cell is the feature emphasized (Fig 2 7 ) This term applies strictly

to cystidia with content staining deep blue with cresyl blue, and is not used much in the systematics of agarics Pseudocystidia [Fig 28 (with a basidium for comparison)], at least in the sense of some authors, are the

more or less filamentous, often contorted cells in the hymenium of Russula

and Lactarius Their content is =h refractive when revived in KOH To

this author, a nomenclature of cystidia based on the nature of the content

is never likely to be satisfactory In the genus Tylopilus (Boletaceae) one

finds species with cystidia apparently having an amyloid content at a certain stage of development (Smith and Thiers, 1971) Only a small

1 Morphology and Classification 23

number on any pileus have amyloid bodies Large, subcylindric to fusoid

macrocystidia [Fig 27 (often regarded as a subtype of pseudocystidia or

glococystidia because of the content)] are a feature of Lactarius in

particular

Individual genera, such as Lactarius, often show great diversity in the

cystidia found on various surfaces of the basidiocarp Incrustations are a

constant feature of the cystidia of some species, and a tendency to pro­

duce simple to contorted projections (or branches) is notable, for example,

in many species of Mycena In summary it may be stated that the present

tendency in the nomenclature of cystidia is to name each morphological or

chemical variation encountered This is creating a very cumbersome

terminology The important details to record in the course of taxonomic

work are ( 1 ) position, ( 2 ) shape, ( 3 ) thickness of wall and any color

which is present, ( 4 ) incrustations (in water mounts of fresh material, in

KOH on revived sections, in Melzer's, and in NH^OH), ( 5 ) type of cell

content in each of the media mentioned in ( 4 ) above, ( 6 ) branching or

protrusions of any type from the surface, and ( 7 ) size

The phylogenetic value of cystidia is to me still somewhat obscure

Without question, they are characteristic of hymenomycetous fungi Re­

lated species in the Agaricales often have the same type, though it is also

known that in two closely related species one may have cystidia and one

not (see Mycena; Smith, 1947) In present systematic studies on agarics

they furnish important characters for species recognition When we under­

stand their function better we will perhaps be better able to evaluate the

meaning of their diversity to agaric systematics One theory at present is

that the pleurocystidia aid in the evaporation of moisture, which keeps

the humidity high in the area of the sporulating basidia Attempts to de­

fine genera on the presence or absence of a certain type of cystidium (see

Smith, 1951) are not likely to stand the test of time

3 THE SPORES

The basidiospores furnish a number of the most reliable features used

in the taxonomic and phylogenetic studies of the fungi Historically, the

color of the spore deposit was one of the features, if not the first, of the

spores to be used in the systematics of gilled fungi Of the commercially

grown species we find Flammulina velutipes and Lentinus edodes with

white to whitish spore deposits The Pleurotus ostreatus variants have a

lilac-gray spore deposit, Pholiota nameko gives a brown deposit, Agaricus

bitorquis and Agaricus bisporus a dark chocolate-colored one, and

Vol-varieUa volvacea a reddish one In all of these the deposit color is im­

portant in placing the species in a family In the early classification of

Fries (1821) spore deposit color was used, and this has continued to the

present day with some adjustments In the Tricholomataceae, for instance, species with white, pale yellow, pinkish buff, pink, and lilac-gray deposits are included In the so-called "pink-spored" group, most species, especially

in Pluteus, show a reddish-cinnamon color We now make no distinction between "black" and "purple brown": Coprinus has brown-spored species, and in Psathyrella black-spored to reddish-cinnamon spores are found

The color in nearly all agaric spores is located in the wall

More important than color of deposit, perhaps, is spore detail as ob­served under the microscope Spore size has been a standard taxonomic character ever since the microscope came into general use In recent years the tendency has been to describe the ornamentation per se In the Agari­cales, spore shape is generally given in a three-dimensional context: e.g., globose, ellipsoid (Fig 4 ) , ovoid (Fig 5 ) , etc These terms are to be inter­preted literally Spores of many species, however, are somewhat bilaterally symmetrical (Fig 2 9 ) If viewed in a profile view as attached to the ste-rigma, the shape may be inequilateral (Fig 6 ) but, in face view, elliptic

(Fig 4) or ovate (Fig 5 ) In Coprinus many species have distinctly com­

pressed spores—wider than they are thick (Fig 2 9 )

a The Wall Many species have spores with thin smooth walls lacking

pigmentation as viewed by transmitted light Variations from this set of characters involve wall thickening, pigmentation, presence of ornamenta­tion (the pattern varies with the species), and development of germ pores The latter are spots in the wall filled with a readily digestible substance through which the germ tube emerges upon germination These pores vary in position from species to species, but for most agarics they are apical or just off center at the spore apex When one reahzes that fungi are found exhibiting all or practically all combinations of the spore, cystidial, tramal, and macroscopic features, it is no wonder the number of species seems endless

b The Veils The development of most species, in the Tricholomataceae

for instance, involves gymnocarpy: the exposure of the hymenium throughout the development of the basidiocarp In other families, e.g.,

Boletaceae, genus Suillus, on some species a sterile growth which is a

continuation of the pileus margin, grows to, and surrounds, the stipe Thus the young hymenium develops in a protected chamber in which a high level of humidity is, presumably, rather easily maintained As the spores mature, the veil breaks from pressures created by the expanding pileus, and the remains of the veil either form a ring (annulus) on the stipe or the fragments adhere along the margin of the pileus Such a veil is termed

a marginal veil

1 Morphology and Classification 25

IV E D I B I L I T Y AND POISONOUS P R O P E R T I E S

In a sense the poisonous properties of mushrooms are not in the scope of

this work, since no commercial grower would think of trying to market

dangerous species as food However, in an overall review of the diversity

in fleshy Basidiomycetes and Ascomycetes, edibility as a taxonomic char­

acter has a place along with all the other features of a species Through­

out the present discussion I have tried to emphasize the diversity in the

fleshy fungi, and the variability of many of the taxonomic characters The

question of edible vs poisonous properties follows the same pattern of

variability and diversity, and is judged, to make matters more complicated,

against the great diversity in the testing organism (the human being)

This is the crux of the confusion in much of the mycological literature on

poisonous and edible fungi We now know that the amount of poison in a

species varies considerably with the strain or race tested (Tyler et al.,

1966), and that apparently, in some edible species geographic races are

In other famihes (e.g., some of the Coprinaceae), the young button

forms in an aggregation of mycelium (in some species), and this may en­

velop the button until it is partly expanded, at which time the rapid

expansion of the pileus pulls apart the fibrils of this superficial coating

(see Smith, 1975, PI 182, p 234) This type of veil, which is free from the

cap surface and very easily removed, is termed an outer (or universal)

veil The remains of such a veil may also be distributed in part over the

stipe but, again, are not attached to it and soon disappear

In a typical member of the Amanitaceae (Amanita), a more complicated

system of veils has developed in which an outer veil is usually evident

from warts left on the pileus and a cup or volva around the base of the

stipe A second veil is represented by a layer of sterile tissue extending

from the pileus margin to the stipe and still covering the gill cavity after

the outer veil breaks up It is more firmly attached to the stipe than to the

pileus margin and when it breaks usually leaves a ring or annulus on the

stipe often very near the apex In some groups of agarics the partial and

outer veils become fused, and copious remains of both are left ornament­

ing the stipe as zones, patches, or scales This type occurs in some species

of Agaricus

The features of the veil offer many characters of taxonomic value other

than the position of the remnants They involve the shape of the hyphal

cells, wall thickness, color, and presence or absence of incrustations (Fig

30, a-d), development of special types of branches (often with contorted

projections), and general hyphal arrangement

known which are mildly poisonous (see Pholiota aurea) It is also known

(Simmons, 1971) that people vary in their tolerance to at least certain poisons The mushroom grower must deal with all these possibilities in testing species not previously marketed The testing of new strains or species should, it now appears, be done on the basis of a tester trying the species every day for about a week, and also testing it on many different people As records accumulate on the eating of wild mushrooms, we find more and more cases of "mild" poisoning from supposedly edible species This situation might be referred to as double variability since a variable organism is being tested against another variable organism Species col­lected in the wild and sold on the market present a special problem The commercially grown product is much safer because growers have been aware over the years that problems existed Also, the strains marketed today are those with a long history of reliability as edible species

V FAMILY AGARICACEAE F R I E S

Stipe typically centrally stipitate; pileus ordinarily readily separable from the stipe; lamellae free or practically so and readily seceding; spore deposit some shade of chocolate color to blackish; spore wall usually deeply colored as seen in mounts in KOH and wall more or less thick­ened; partial veil present and leaving a more or less distinct annulus on the stipe, or partial and outer veils intergrown and stipe sheathed and/or annulus double

A Type Genus: Agaricus Fries

AGARICUS FRIES

In addition to the family characters given in the above diagnosis, the fibrillose cuticle of the pileus with the fibrils more or less radially arranged and at times becoming broken up into squamules is important Chemical characters (Bataille, 1931) are also important in the genus

B Type Species: Agaricus campestris Fries

1 Agaricus bisporous (Lange) Imbach, Mitt Naturforsch Ges Luzern 15, 15 (1946)

Psalliota hortensis var bispora Lange, Flora Agar Dan 4, 58

(1939)

Pileus 5-10 cm broad, convex or flattened over the disc, dull brown (near "wood brown" to more or less tawny) overall, dry, fibrillose, edge

1 Morphology and Classification 27

white floccose from the veil Context firm, pallid at first, slowly becoming

reddish, odor acidulous, taste pleasant Shaffer reaction negative

Lamellae free, crowded, narrow, flesh pink at first, finally blackish

brown, edges white-crenulate

Stipe 3-5 cm long, 10-15 mm thick, thicker near base, pithy becoming

fistulöse, whitish, often flesh tinted near apex, slightly flocose below the

ring; annulus white, thick, narrow, striate above

Spore deposit blackish brown Spores 6-7.5 X 4.5-5.5 ju.m, broadly

ellipsoid Basidia two-spored Cheilocystidia broadly clávate, hyaline to

brown, 17-44 X 8-12

Rather common on manured soil, Europe, July-September

Observations The above description is based on that of Lange (1939)

and of M0ller (1950) The taxonomy of the cultivated two-spored variants

of this species is indeed complex and is still a problem The simplest way

to overcome this difficulty would be to designate and completely describe

material from Denmark as a type, in order to fix the name A bisporus to a

definite concept Lange described a white form of P hortensis also, but

it is not necessarily the same as the two-spored white variant grown in

the United States I have seen "semialbino" basidiocarps of a number of

dark-spored agarics (in which the spores were normally pigmented), so it

is reasonable to assume that the white mutation in Psalliota hortensis

could occur a number of times and that no two of them would be exactly

alike This is of some significance to the mushroom grower

2 Agaricus bitorquis Quélet, in C R Assoc Fr Av Sei 12 (1884)

Agaricus rodmani Peck, Annu Rep N Y State Mus 36, 45 (1884)

Illustrations: PI 6

Pileus 5-12 cm broad, convex, expanding to nearly plane-shaped and

finally shallowly depressed, surface dry, silky-fibrillose and white, occa­

sionally areolate in age and disc grayish Context thick and hard, white,

slowly becoming pale vinaceous near the gills, not changing color when

cut, odor and taste mild, agreeable

Lamellae free but approximate and attached by a shght tooth at times,

narrow to moderately broad (up to 10 mm), pinkish gray becoming pale

dull vinaceous pink and finally blackish

Stipe short, length usually less than width of pileus, 2 - 5 ( 7 ) cm long,

1.5-3.5 cm thick above, usually narrowed near the base; with white

rhizo-morphs, solid, fibrous, white, unchanging, or where handled slowly be­

coming vinaceous brown, glabrous above and below the annulus; annulus

±: median, double (usually with a flaring upper limb and a less flaring

lower one, white at first

Spore deposit blackish brown Spores 5-6 X 4-5 μτη, subglobose to

broadly elHpsoid, fuscous brown in KOH under microscope Basidia

four-spored Pleurocystidia scattered to rare, 28-36 X 9-14 μτη, clávate to saccate and thin-walled Cheilocystidia 10-18 X 6-12 μτη, clávate, yellow­

ish in KOH Hyphae of pileus cuticle 2-6 μπ\ wide Clamps absent

Solitary to gregarious on hard-packed soil in school yards, along streets,

in tennis courts, etc., common in spring and fall

Observations The description presented here is from collections made

in North America and applies particularly to Agaricus rodmani Peck

Peck described his species in his report for the year 1882 which appeared

in 1884, Quelet reported A bitorquis in August 1883

VI FAMILY STROPHARIACEAE SINGER & SMITH

Spore deposit purple brown to purplish fuscous; spores in water mounts with a purphsh to hlac tint but in KOH soon dingy yellow-brown (near bister to snuff brown), typically with an apical pore; cuticle of pileus usually a cutis or ixocutis; chrysocystidia present in hymenium of many species; typically growing on wood or soil rich in lignicolous debris such

as peat

A Type Genus: Stropharia ( F r ) Quelet

3 Stropharia rugoso-annulata Farlow apud Murrill, Mycologia 14,

139 (1922)

Stropharia elegans Murrill, Mycologia 14, 140 (1922)

Stropharia rugoso-annulata Farlow apud Burt, Icones Farlowianae

Illustrations: PI 65 (1929) Cambridge, Massachusetts

Stropharia ferrii Bres., Riv Sei Nat ''Natura" Milane 19,17 (1928)

Illustrations: Pi 3; also J Cage, L Lang, and A H Smith,

"Mushroom Book," Plate V Hollander Workshop Inc., New York

Pileus 5-15 cm broad, obtusely conic at first, becoming obtusely nate or nearly plane; margin inroUed at first, surface glabrous or streaked with innate fibrils not viscid, sometimes squamulose around the disc in age from the rupturing of the cuticle; evenly colored, pecan brown to chestnut or purphsh red, in age sometimes paler and near ochraceous tawny; tawny brown when dried; flesh about 1 cm thick, firm, white

umbo-Lamellae adnate but soon seceding, crowded, at first whitish to pale olive, then deep quaker drab, drying fuscous to dark cinnamon brown

1 Morphology and Classification 29

VIL FAMILY PLUTEACEAE KOTL & POUZAR

Spore deposit reddish cinnamon to pink; lamellae free (but approximate

to stipe in some) from stipe and stipe typically easily and ± clearly

separable from pileus; gill trama formed to a degree by endocystidia (see

Walker, 1919, 1920), arranged in ± of a V-shaped pattern with the point

of the V toward the gill edge; veilless or with an outer veil, very rarely

with only an annulus present; spores cyanophyllic

narrow, becoming as broad or broader than the thickness of the flesh, the

edges even or becoming uneven

Stipe ( 5 ) 9-14 cm long, 10-16 mm thick, shghtly tapering upward,

solid, soft within and slightly yellowish, olive buff and striate below the

ring, whitish above and more deeply striate, as well as floccose scabrous;

annulus superior, thick, composed of two layers, the lower layer greatly

thickened and split radially, the rays extending beyond and outside the

margin of the pileus in the form of about 12 horns or claws which curve

upward to clasp the pileus, upper surface grooved or sublamellate from

gill-impressions, in breaking the upper layer often leaving fragments on

the margin of the cap

Spores 10-13 X 7.5-8.5 ( 9 ) μχη, broadly ovoid in face view, subellipsoid

to slightly inequilateral in side view, apex slightly truncate from a small

apical pore, not flattened smooth, dark yellowish brown in KOH near

"bister." Pleurocystidia abundant, 28-36 χ 8-11 μχη, obovate to mucronate,

content homogeneous or with a small highly refractive amorphous body

when revived in KOH Cheilocystidia similar to pleurocystidia or more

fusoid ventricose (tapered more above), with or without a small, amor­

phous, highly refractive body Gill trama subparallel as revived in KOH,

hyaline Pileus trama with a cuticle of more or less radially arranged

hyphae which, when sections are revived in KOH, appears to consist of

two parts, a basal mat of yellowish brown hyphae from which numerous

hyphae 5-8 μπ\ in diameter project (in the mounting medium) to form

a turflike tangled covering, the end cells of these hyphae not or scarcely

differentiated as pileocystidia but their contents smoky brown in KOH,

clamp connections present Flesh proper of compactly interwoven hyaline

hyphae

Singly to scattered on rich cultivated soil; North America and Europe

Observations As is true for so many agarics, there are variants of this

species still in need of critical taxonomic study, but the type variant is

one of the most distinctive mushrooms known

Α Type Genus: Volvariella Speg

VOLVARIELLA SPEG

In this genus a volva is present and an annulus absent In Pluteus, the

other common genus, both an annulus and volva are absent

B Type Species: Volvariella argentina Speg

4 Volvariella volvacea ( F r ) Singer, Lilloa 22, 401 (1951)

Agaricus volvaceus Fr., Syst My col 1, 278 (1821)

Illustrations: PI 7

Pileus 5-10 cm broad, ovoid expanding to campanulate or (rarely) ±: convex, dry, fibrillose, darker on disc than on margin at maturity, blackish brown to bister over disc at first, grayish with darker streaks (virgate) toward margin Context thickish in the disc, soft, white, taste mild, odor somewhat aromatic

Lamellae close, broad, free, edges fimbriate, white when young, deep flesh color at maturity

Stipe 5-12 ( 1 4 ) cm long, ( 3 ) 6-10 ( 2 0 ) mm thick, enlarged shghtly downward, base ± bulbous at times, stuffed then hollow, dry and fibril­lose, pallid to dull brown

Volva large, margin free and variously lobed, membranous, brownish, floccose

Spores 8-10 χ 5-6 μτη, in face view ±: ellipsoid to ovoid, smooth Basidia

four-spored Pleurocystidia 35-100 (113) X 8-36 μττι, subcylindric to

fusoidventricose or apex enlarged, abundant Cheilocystidia 23107 X 8

-30 μττ\, fusoid-ventricose to mucronate Pileus cuticle of hyphae 2-33 μττ\

wide Clamps absent

Cultivated on straw in the Orient

Observations The variant currently grown in the Orient (Chang, 1972)

departs in some features, possibly minor characters, from the one de­scribed by Kühner and Romagnesi (1953) Since the name goes back to Bulliard, the concept of the French authors is doubly significant The strain or variant pertinent to the present work is that described by Chang (1972)

Vm FAMILY TRICHOLOMATACEAE ROZE

Stipe varying from centric to lateral or absent; pileus and stipe con­fluent; lamellae typically attached; sport deposit white to buff or pinkish buff; spores smooth or ornamented, amyloid, dextrinoid or inamyloid; partial veil present or absent

1 Morphology and Classification 31

1 Pleurotus ostreatus ( F r ) Kummer, "Führer in die Pilzkunde," p

105 1871

Agaricus ostreatus Fries, Syst My col I, 182 (1821)

Illustrations: Pis 4-5

Pileus 4-12 ( 1 5 ) cm broad, typically fan shaped and shelving (but if

on top of a hard surface often ± stipitate to marginate behind or with a

practically central stipe), surface glabrous, moist, hygrophanous, when

fresh dark fuligineous to watery gray slowly becoming a dingy tan to clay

color in fading Context thick, odor fungoid, often strong in age; taste

fungoid to (in age) bitter or disagreeable

Lamellae close, broad, decurrent (if a stipe is present), typically anas­

tomosing near area of attachment, pallid to (in age) cream color, and

edges at times staining brownish

Stipe absent to present and if present lateral to eccentric or rarely cen­

tral, 2-6 cm long, 1-3 cm thick, solid, pallid within, base often somewhat

pubescent

Spore deposit lilac gray as air dried; spores 7-9 X 3-3.5 /xm, sub­

cylindric in face or back view, in profile cylindric to slightly allantoid,

smooth, yellowish in Melzer's

Basidia four-spored, 26-27 X 5-8 μχη, hyaline in KOH, narrowly clávate

Pleurocystidia none; cheilocystidia apparently lacking Gill trama

sub-parallel to interwoven, hyaline in KOH, nonamyloid, hyphae 5-12 μχη

wide Cuticle of pileus a cutis of hyphae 4 - 6 μτη wide and smooth thin

walls Clamps present

Observations Fries (1821) described the species as having a

blackish-cinereous pileus which fades On this basis the variant described here is

considered to be identical with (or very close to) the type variety There

have been conflicting statements in the literature as to the color of the

spore deposit I have observed it to be whitish at first and lilac gray after

air drying There are many variants of this species (or closely related

taxa?) In the central United States a whitish variant occurs that many

people prefer to the one described here

2 Lentinus edodes (Berk.) Singer, Lilloa 22, 279 (1949)

Agaricus edodes Berkeley, Challenger Exped 3, 50 (1878)

Illustrations: PI 7

Pileus ( 4 ) 5-12 ( 2 0 ) cm broad, convex to nearly plane or with a low

umbo, surface dry and d= appressed-fibrillose, the cuticle breaking into

scales of various sizes and shapes, often rimóse with white context show­

ing, color pale to dark reddish brown Context white or brownish near the

cuticle, firm to tough-fleshy in age, softer in immature specimens; taste

acidulous, odor slight but not distinctive