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CONTENTS 
Introduction ix 
Major Groupings of Imperfect Fungi and Their Importance 
in the Biosphere x 
Cytological and Morphological Features of Imperfect Fungi xvi 
Factors Affecting Growth and Sporulation of Imperfect Fungi xviii 
References Cited xxi 
PART I. PHYSIOLOGY 1 
ISOLATION 1 
CULTURE MEDIA 2 
MAINTENANCE OF STOCK CULTURES 2 
PHYSIOLOGY: NUTRITION AND ENVIRONMENT 3 
USE OF IMPERFECT FUNGI TO ILLUSTRATE BIOLOGICAL PRINCIPLES 4 
PART II. TAXONOMY AND IDENTIFICATION 6 
THE SACCARDO SYSTEM OF CLASSIFICATION 6 
FAMILIES OF MONILIALES 7 
KEY TO GENERA 8 
MUCORALES 8 
MONILIALES 9 
HELICOSPORES 9 
NOT HELICOSPORES 10 
MONILIACEAE 10 
DEMATIACEAE 17 
TUBERCULARIACEAE 25 
STILBACEAE 26 
SPHAEROPSIDALES 28 
MELANCONIALES 33 
MYCELIA STERILIA 34 
SIMPLIFIED KEY TO SOME SELECTED COMMON GENERA 35 
THE HUGHES-TUBAKI-BARRON SYSTEM OF CLASSIFICATION 40 
vii 
ALTERNATE KEY TO SERIES AND GENERA 41 
ARTHROSPORAE 44 
MERISTEM ARTHROSPORAE 44 
ALEURIOSPORAE 45 
ANNELLOSPORAE 48 
BLASTOSPORAE 48 
BOTRYOBLASTOSPORAE 50-
POROSPORAE * 51 
SYMPODULOSPORAE 52 
PHIALOSPORAE 55 
DESCRIPTIONS AND ILLUSTRATIONS OF GENERA 59 
REFERENCES 198 
GLOSSARY 212 
INDEX TO GENERA 216 
vill 
INTRODUCTION 
The Deuteromycetes or Fungi lmperfecti (former taxonomic designations) are an anomalous, 
heterogeneous assemblage of asexual ascomycetes and basidiomycetes which no longer have formal 
taxonomic status. These fungi were traditionally considered as lesser fungi because they lacked the 
perfect stage—sexual reproduction. The absence of asci (ascomycetes) and basidia (basidiomycetes) 
prevented their assignment to a natural taxon and necessitated .artificial non-sexual characteristics to 
describe and classify them. This genetic inability of many imperfects to reproduce sexually is considered 
a primitive condition and in contemporary mycology presents a taxonomic quandary. Alexopoulus et al, 
1996, provide excellent scientific rationale for excluding imperfect fungi from contemporary fungal 
systematics, and discuss considerations needed to develop logical and valid taxonomic approaches to 
determine their phylogeny (1). Consequently, the taxons which previously were recognized as 
taxonomically valid for the deuteromycetes (imperfect fungi), are used in this book only to facilitate their 
identification. 
The imperfects are important eucaryotic microorganisms (possessing nuclei and organelles) which 
affect humans and most other life forms in a myriad of ways. The need to determine their identities is 
paramount in research, industry, medicine, plant pathology and in many other disciplines. Imperfect fungi 
are identified according to their conidial or non-sexual states. Nevertheless, many imperfects possess 
sexual structures of known ascomycetes or basidiomycetes, whereas others produce no conidia and/or 
sexual structures. Roper, 1966, described a parasexual cycle in which genetic recombination can occur in 
hyphae (16). This observation suggests that some fungi may never have possessed sexual structures or 
required sexual reproduction for genetic exchange. However, while there is little data which substantiates 
that pansexuality occurs under natural conditions today, it could have occurred during the origin and 
evolution of these fungi. 
When sexual structures are associated with the conidial state, a valid taxonomic status can be ascribed. 
However, this often does not occur, and for practical purposes is not important. Although the scientific 
name of the sexual state constitutes a valid taxonomic designation, the imperfect name is retained for 
practicality and for conventional use. Therefore, to identify the imperfect fungi, it is necessary to know 
their conidial morphologies regardless of whether the sexual state is also present in culture or in nature. 
The deuteromycetes constitute an important group of fungi which require continued study despite their 
obscure and confounding systematic relationships both to themselves and to other fungi. Barron, 1968 
(2), Hunter and Barnett, 1973 (10), Hunter « tf al., 1978 (11), and Alexopoulus et al. (1) provide additional 
information on many aspects of the morphology, sporulation, growth, ecology and economic importance 
of imperfect fungi. 
Scanning electron and light photomicrographs are provided on several of the following pages. They 
show conidia, conidiophores, and hyphal structures found on many different kinds of imperfect fungi. 
Compare them with like illustrations in the book to better understand how these structures are important 
in identifying imperfect fungi. 
IX 
MAJOR GROUPINGS 
OF I M P E R F E C T FUNGI AND T H E I R 
IMPORTANCE I N T H E B I O S P H E R E 
The imperfect fungi or deuteromycetes have been classified according to principles established by 
Saccardo in Sylloge fungorum (17). While this taxonomic system is no longer valid, it is still the best way 
to learn the mycology that is necessary for identifying the imperfect fungi. It is also the primary means 
used in this book to identify imperfect fungi. The scientific names of imperfect fungi are still used, albeit, 
only in a non-taxonomic sense, and as a necessity to know their practical importance in the biosphere. 
The Hughes-Tubaki-Barron System (conidial ontogeny) has also been used as a way of classifying and 
identifying these fungi (2, 9, 18). Details pertaining to this system are provided on pages 40-44 and 
related identification keys are found on pages 44-57. The use of conidial and conidiophore ontogeny for 
identifying deuteromycetes should be used by individuals who are well versed in mycology. The shape, 
pigmentation, and septation of conidia are important characteristics in the Saccardo System but reduced 
to secondary importance in the Hughes-Tubaki-Barron System. 
To better understand the Saccardo System, common and economically-important imperfect fungi of 
the four form orders will be presented. Following the Saccardoan System, the species of the form orders 
can be separated into four distinct groups of fungi. This provides a basis from which to begin a search 
(appropriate key) for the identity of an unknown fungus. The form orders are as follows: (I) Moniliales -
Conidiophores and conidia occurring free and distributed over the mycelium. Conidiophores may be 
separate, in clusters, or in tightly-packed groups. Illustrative examples and accompanying descriptions of 
many of the diverse genera in this group are provided from pages 68 through 161; (2) Sphaeropsidales -
Conidiophores and conidia contained within asexual fruiting bodies called pycnidia. See pages 162 
through 187 for descriptions and illustrations of pycnidia-producing fungi. (3) Melanconiales - Conidia 
typically produced under natural conditions in an acervulus, an open saucer-shaped fruiting body. In 
culture, conidiophores may be single or in compact groups similar to sporodochia of the Mormiaies. 
These fungi can be found on pages 188 through 194; (4) Mycelia Sterilia - Species in this form order are 
genetically incapable of producing conidia or any kind of reproductive cells. Sclerotia or other survival 
structures occur in the mycelium. Descriptions and illustrations of the three species depicted in this book 
are provided on pages 196 and 197. 
Conidiophores ot Paecilomyces sp. with typical flask- Conidia of Trichoderma sp. emerging from apices ot the 
shaped phialides and catenulate conidia. conidiophores. 
X 
Two of the spomlating form orders, Moniliales and Sphaeropsidales can be separated into several 
form families. Characteristics are predicated upon such artificial features as color, shape, and consistency 
of the pycnidium in the Sphaeropsidales, or color of the conidia and presence of synnemata or 
sporodochia in the Moniliales. The form family taxon is not used in Mycelia Sterilia and only one form 
family exists in the Melanconiales. 
There are at least 1,400 form genera of imperfect fungi and several thousand species.The most 
common in nature and the most economically important are found in the form order Moniliales. Some are 
pathogens of plants, animals and humans, some produce toxins, while others are important in the 
production of antibiotics and other chemicals. In the Saccardo System, it is the color and morphology of 
the conidia which are used to separate form genera into sections. For example, one-celled hyaline (devoid 
of any color) conidia are called hyalospores; colored, one-celled conidia are phaeospores; didymospores 
are two-celled; and transversely septate conidia with three or more cells are phragmospores. Add hyalo to 
phragmospore (hyalophragmospore) and it is a hyaline, transversely septate conidium; cylindrically-
spiraled, one to several cell formations are helicospores, regardless of the presence or absence of color. 
Problems encountered when using the Saccardo system are variations in type of fruiting body (acervulus, 
sporodochium, and pycnidium), conidium color and conidium morphology. These structures can vary on 
different media and in their response to varying environmental conditions. Consequently, what is 
described in the keys may differ slightly to significantly when the fungus in question is grown on 
different media or when it is incubated at different temperatures. Nevertheless, time and experience will 
negate these factors. Therefore, because of its simplicity and practicality, the Saccardo System is still the 
best way for students and others to study and identify imperfect fungi. 
SACCARDOAN FORM ORDERS 
FORM ORDER MONILIALES 
Most species of deuteromycetes reside in this form order and are grouped into four form families (see 
page 7). This is the only form order in which form families are described in this book. Form families 
Moniliaceae and Dematiaceae have species which are delimited by one or more of the following 
Conidia In basipetal chains radiating from the apex of an 
Aspergillus sp. conidiophore. 
xi 
characteristics: conidial septation; conidiophore appearance and branching; conidial morphology; true 
and pseudomycelium (some imperfects are yeasts without true hyphae); the manner in which the conidia 
are produced; presence of chlamydospores and morphology; conidia produced in chains or in a head; 
presence or absence of mucilage; conidial number and arrangement at apex of the conidiophore; conidia 
produced on conidiophore or mycelium; and exogenous or endogenous production of conidia. Refer to 
page 68 through page 145 for numerous examples of the Moniliaceae and the Dematiaceae. Note that 
imperfects in this form order with hyaline conidia are members of the Moniliaceae; those with pigmented 
conidia and/or conidiophores reside in form family Dematiaceae. The reason that the fungi of these two 
form families are discussed together is because the only difference between the species is the color of 
their conidia and conidiophores. This seemingly obvious color difference is at times difficult to 
determine in culture and under the microscope. However, careful use of the microscope, diligence and 
experience in identifying these and other fungi, will in time allow orje to make accurate determinations of 
pigmentation, along with many other pertinent fungal characteristics. 
Many of the more common fungi are found in the form families Moniliaceae and Dematiaceae. 
Species of Aspergillus (page 95), Penicillium (page 95), Alternaria (page 132) and Stemphylium (page 
132) are routinely isolated from the air and numerous other substrates. These genera and several other 
species of the Moniliaceae are discussed here. Aspergillus fumigatus is an opportunistic pathogen of 
humans and other animals and is responsible for the human disease aspergillosis, a pulmonary disorder. 
Penicillium chrysogenum and closely related species are the sources of penicillin, an important 
antibacterial antibiotic, which has saved countless humans from death and serious illness for many 
decades. Other species of Penicillium are responsible for the contamination of food and clothing. 
Gl'tocladium spp. (page 93) are similar to the penicillia, but differ at maturity by having the spore mass 
encompassed by mucilage. One species, G. roseum is a good example where identification is confusing 
because it produces two different conidial types, one being the Gliocladium type and the other that of 
Veriicillium albo-atrum (page 92). Fortunately, this is unusual, but warns one to not always consider 
fungal cultures contaminated when two distinct conidial types occur in the same culture. Verticillium 
albo-atrum is a destructive plant pathogen that causes a wilt of some economically-important plants. 
Monilia (page 73) cinerea var. americana, the pathogen of brown rot of peach and other fruits, is often 
found as a contaminant of microbial cultures. Geotrichum candidum (page 68) is the causative agent of 
geotrichosis, a human disease which can occur orally, in the intestine and as a pulmonary disease. 
Species of the genus Candida (page 71) are common in the Moniliaceae. Note that this fungus is not 
always filamentous, but can possess yeast-like cells. An important species C. albicans, is an 
opportunistic human pathogen causing oral and vaginal diseases and may become systemic. This 
filamentous yeast can be differentiated from other Candida spp. by the production of S to 12 pm 
spherical chlamydospores on corn meal agar. 
One-celled Gliocladium sp. conidia in mucilaginous masses on penicillate branches of conidiophores. 
xii 
Many species having pigmented conidia and/or conidiophores, reside in the form family Dematiaceae. 
Many of these species are also common and/or economically-important fungi. Stachybotrys (page 89), a 
soilborne saprotroph, has pigmented single-celled conidia and conidiophores that slime down to form 
glistening beads. Cladosporium (page 107) is prevalent in the air, and some species are plant or human 
pathogens. This fungus has a highly branched conidiophore and one-or two-celled conidia that occur in 
chains. Since all conidia of one species are not always of the same cell number or size, purity of a culture 
cannot be determined by this means. Aureobasidium (page 71) is a filamentous yeast, hyaline when 
young, becoming dark with age. Aureobasidium is often confused with species of Candida, but 
pigmentation appears in its hyphae which is not found in Candida. One species, A. pullalans is 
saprotrophic, but can become an opportunistic pathogen of plants. This same fungus is also known to be 
a major agent in the deterioration of painted surfaces. Many species of Helminthosporium (page 125) are 
well known to plant pathologists as pathogens of grasses. These fungi produce dark cylindrical conidia, 
which are multiseptate and usually have rounded ends. The conidia of Bipolaris (page 127) and 
Dreschlera (page 123) are nearly identical to those of Helminthosporium but differ in the mode of 
conidial formation. The ends of the conidia vary only slightly making the differentiation of species 
between Bipolaris, Dreschlera and Helminthosporium difficult. Illustrations along with the keys are most 
helpful in correctly identifying species of these three genera. The most commonly encountered fungus in 
the Dematiaceae is Alternar'ta (page 133), which produces large muriform conidia, often borne 
acropetally in chains. Isolates of this fungus are readily recovered from air, soil, decaying vegetation and 
from diseased potatoes and tomatoes. 
Imperfect species which have conidiophores united in columns or clusters reside in the form family 
Stilbaceae (pages 152 - 161). These multiple fused conidiophores are called synnemata or coremia and 
tend to be more plentiful in aging cultures. The conidia are produced on the upper portions of the 
synnemata. Some isolates of the Stilbaceae do not form synnemata on all media making identification 
most difficult. Isaria spp. (page 157) are frequently isolated from soil and grow profusely on most 
mycological agarmedia. One species, Pesotum ulmi, is well known to plant pathologists because it is the 
imperfect form of the fungal pathogen that causes Dutch elm disease. The synnemata of P. ulmi are tall 
and have a rounded mass of light-colored conidia embedded in mucilage. 
The presence of sporodochia in the mycelium distinguishes form family Tuberculariaceae from the 
other three form families of form order Moniliales. Refer to pages 146 - 151 and observe the many 
different types of sporodochial fungi. A sporodochium is a cushioned-shaped structure made up of 
closely grouped conidiophores. Definitive identification of sporodochial-producing fungi is often 
difficult because the structures often vary with cultural conditions. Some, but not all species of Fusarium 
(page 131), produce sporodochia. Species of Fusarium. are pathogens of humans, insects, plants and are 
Catenulate conidia of Penicillium sp. on phialides of a Arthrospores of Geotrlchum sp. 
conidiophore. 
xiii 
abundant in the air and soil. It is easy to identify isolates to genus because of their characteristic banana-
shaped conidia. However the tremendous variability in conidial size, microconidia and macroconidia, 
make them difficult to speciate. Species in the genus Epicoccum (page 151) are frequently isolated from 
soil and decaying wood. This fungus has dark sporodochia, from which compact or loose conidiophorcs 
give rise to dark, globose dictyospores (conidium has both oblique and transverse septa). 
FORM ORDER SPHAEROPSIDALES 
There are four form families in this form order and all of the species have well defined asexual fruiting 
bodies i.e. pycnidia (page 162 through 187), Pycnidia are easily seen at low magnifications with a 
compound or stereo-microscope. They have conidia which are either endogenously produced (inside the 
pycnidium), or that differ from most other imperfect fungi and are exogenously produced. According to 
Saccardo, the form families are differentiated as follows. Sphaeropsidaceae - dark pycnidia, leathery to 
carbonaceous, which may or may not be produced on a stroma, usually having a circular opening; 
Zythiaceae - physical characteristics as in form order Sphaeropsidaceae, but the pycnidia are bright-
colored and waxy; Leptostromataceae - upper half of pycnidium fully developed, rather than in the basal 
portion; Excipulaceae - Pycnidia are cupped or saucer-shaped. In this book, we do not separate pycnidia -
producing fungi using the four form families, although we may use a particular characteristic from a 
given form family as part of the key composition. 
Many members of the form order Sphaeropsidales are saprotrophic, although some are plant pathogens 
and others infect insects and other fungi. Among the more common form genera are Phoma, (page 163), 
Phyllosticta (page 163), Sphaeropsis (page 177), Coniothyrium (page 177) and Septoria (page 183). 
Many of the species of these five genera are pathogens of plant stems and leaves. Problems in identifying 
these fungi are obvious when comparing Phoma and Phyllosticta. Their pycnidia and conidia are so 
similar that distinctions are at best arbitrary. Both have dark, erumpent pycnidia enclosing short 
conidiophores that produce hyaline, non-septate conidia. Sphaeropsis is another form genus which is 
similar to Phoma. Septoria (page 183) is a form genus with approximately 1,000 species, most being 
plant pathogens. Many of the species names come from their hosts. Obviously, using the host to name the 
fungal species leads to confusion, the proliferation of species, and questionable scientific designations. 
The pycnidia of Septoria are dark, globose, ostiolate, erumpent; they enclose short conidiophores bearing 
long, thin scolecospores. Therefore, the dark pycnidia are round, have an opening, and break out through 
the surface of the substratum and produce endogenous narrow-elongate conidia. 
Germinating cralamydospores of Cylindrocladlum sco- Bristle-covered pycnidia of Chaetomella sp. 
parium. 
xiv 
FORM ORDER MELANCONIALES 
Species in this form order are recognized by a saucer-shaped fruiting body, the acervulus (page 188 
through 195). There is only one form family, Melanconiaceae. Two common form genera are 
Gloeosporium (page 189) and Colletotrichum (page 189). They are both very similar in appearance, 
except that the latter has prominent dark setae associated with the conidiophores. The many species of 
the two genera have conidia which are hyaline, one-celled, and ovoid to oblong. Under certain cultural 
conditions, however, the setae of Colletotrichum fail to form, thereby making it impossible to distinguish 
between the two genera. Glomerella, an ascomycete, is the teleomorph of both form genera which 
indicates that, because of their similar anamorphic states, they should really be in one genus. Another 
common genus is Pestalotia, which produces multiseptate conidia with pointed ends and apical 
appendages (page 193). Species can be either pathogenic or saprotrophic. Careful scrutiny will show that 
species of Cylindrosporium (page 193) are difficult to differentiate from species of Gloeosporium. 
Similar appearing species of different genera present problems even to those who are familiar with the 
fungi. 
FORM ORDER MYCELIA STERILIA 
Species placed here have no known anamorphic or teleomorphic states. They do however, produce 
somatic sporodochium-like bodies, chlamydospores, sclerotia or bulbils. These diversified fungi are 
grouped into approximately 20 genera and because of their heterogeneity there are no form families. No 
asexual or sexual structures are found in these fungi, and therefore they are identified solely by mycelial 
characteristics. Rhizoctonia and Sclerotium (page 197) are two common form genera, both containing 
plant pathogenic species. Clamp connections on their hyphae provide evidence to basidiomycetous 
affinities. Papulospora, another frequently encountered member of this form order produces bulbils 
(shown on page 197) which are sclerotium-like and serve in survival and reproduction. Species of 
Papulospora are saprotrophs of decaying vegetation and are pathogenic to storage structures of some 
plants. 
The imperfect fungi include a diverse array of fungi which occupy every conceivable ecosystem 
within the Biosphere. There are aquatic and terrestrial species; some are saprotrophic, and some are 
pathogenic to humans, animals, plants, microorganisms and to even other fungi. Their many spore and 
somatic types have led to dispersal and invasion of may environments resulting in the evolution of this 
highly diverse group of fungi. 
xv 
CYTOLOGICAL AND MORPHOLOGICAL 
F E A T U R E S OF IMPERFECT FUNGI 
The eucaryotic cellular structure, composition and ultrastructure of the imperfect fungi (DeuterO-
mycetes) have been thoroughly investigated using light and electron microscopy (4, 5, 7, 8, 11, 12). Cells 
of imperfect fungi, like most fungi, are arranged in filaments or threads called hyphae. One filament of 
the hyphae is a hypha, and all hyphae of one fungus constitutes the mycelium. Fungal hyphal cells vary in 
size, color and in their extracellular matrix, when present. However, since hyphae among different kinds 
of fungi are more alike than different, they usually cannot be used as a differentiating character. 
The cells of a hypha are separated from one another by crosswalls called septa. Imperfect fungi have 
one, two or more nuclei in their septate hyphal cells and can possess mitochondria, endoplasmic reticuli 
with ribosomes, microtubules, Golgi bodies, vacuoles, glycogen and lipid. Woronin bodies and Spitzen-
korpers (8), which are unique structures involved in apical hyphal growth may also be present. Often, 
mitochondria and Golgi bodies are found to be closely associated in the cytoplasm. This ultrastructural 
feature has been seen only in imperfect fungi and ascomycetes. Consequently, this association suggests a 
relationship unique to these fungi that differentiates them fromother fungi and other life forms (13). 
Therefore, they have cells, organelles and inclusions similar to, yet different in some respects, from 
protists, metaphytans and metazoans. The asexual spores of deuteromycetes, the conidia, contain similar 
organelles and inclusions. Under light microscopy however, the cytoplasm of the typical imperfect 
fungus appears translucent and granular and lacking discernible nuclei, organelles or other inclusions. 
The hyphae and conidia of Verticillium albo-atrum and V. nigrescens are representative of imperfect 
fungi since they are uninucleate and possess most of the aforementioned intracellular structures within 
their plasma membranes (3). Newhouse et al. found these typical organelles, along with mycoviruses in 
the hyphal cells of Cryphonectria parasitica (14). The majority of fungal viruses do not appear to have 
any deleterious affect upon fungi, but some can debilitate their hosts and cause changes in colony 
morphology, growth rate and pigmentation. This can result in an infected fungal isolate having a cultural 
appearance far different from other fungi of the same species. This is an important consideration in 
fungal identification. Light microscopy of fungal cells reveals little cytological detail; however, 
transmission electron microscopy (TEM) and scanning electron microscopy (SEM) show with clarity the 
organelles, some inclusions, and nuclei within the fungal cell. 
Alexopoulus et al. provide excellent information on fungal ultrastructure and cellular relationships of 
many and diverse fungi (1). Under light microscopy, the nuclei and organelles of the imperfects are 
minute and difficult to observe without killing the cells and applying one or more cytological stains. 
Consequently, intracellular characteristics of the cell(s) are of no value for identification. There is one 
notable feature of the hyphae that is easily seen with the light microscope and enables differentiation of 
an imperfect fungus from a typical phycomycete. This structure is the septum which separates individual 
hyphal cells. All imperfect fungi have septa, unlike most phycomycetes which are coenocytic (lack septa 
and are multinucleate). Ascomycetous and basidiomycetous fungi also possess septa. Within the septum 
there may be one or several pores which provide cytoplasmic continuity between cells. The pores are 
easily observed via TEM but not with light microscopy. Transmission electron micrographs demonstrate 
that nuclei and various organelles can traverse the pores thus moving from cell to cell. Woronin bodies or 
septal pore plugs are known to block pores, especially in hyphal cells that are old or damaged. Imperfect 
fungi with known ascomycetous teleomorphs usually have simple septa, whereas basidiomycetous 
teleomorphs have much more elaborate and complex dolipore septa. 
External to the plasma membrane of the hyphal cell is the cell wall. This is apparent by light 
microscopy and by TEM. This of course is a major difference between metazoans and most protists 
which lack cell walls. Metaphytans also possess cell walls, but the chemical composition of the 
xvl 
microbibrils is different. The imperfect fungal cell wall, in conjunction with microtubules and micro-
filaments that comprise the cytoskeleton, preserve the cytoplasmic integrity of cells and also determines 
the shape of the hyphal cell. Hyphal cells of Sclerotium rolfsii possess an actin cytoskeleton (15). 
Cell growth of the filamentous fungi occurs almost exclusively at the hyphal tip. Transmission 
electron micrographs of the hyphal apex by Grove, 1978 (6), and Grove and Bracker, 1970 (7), show 
apical vesicles which are spherical and membrane bound. The apical vesicles contain the necessary 
elements for plasma membrane extension and cell wall synthesis. More recent studies by Wessels in 1986 
(19) and 1988 (20) provide evidence that the hyphal tip is elastic but ultimately becomes rigid with age. 
Hyphae are the microscopic somatic structures of fungi which are embedded in various organic, 
substrates or in soils. It is the hyphae that absorb nutrients required for growth and reproduction. The 
organization and size of the mycelium is predicated upon substrate availability and nutrient status. While 
additional structures are not usually formed by growing hyphae, some fungi form discrete microscopic 
and/or macroscopic somatic and reproductive structures. Hyphae of some fungi can develop two 
dlifferent kinds of fungal tissues (plectenchyma). These tissues develop from the apical growth of the 
hyphae. Prosenchyma tissue are evident by their loosely woven organization in which the hyphae are still 
mostly discernible. When the hyphae are not discernible and the cells become plant-like, the tissue is 
pseudoparenchyma. Many resistant and reproductive structures develop from the two types of plecten-
chymous tissue. 
One type of somatic tissue structure is the rhizomorph which results from the thickening of the 
hyphae. Sclerotia (page 97) and microsclerotia are other structures in which the hyphae lose their typical 
thread-like appearance and become a mass of cells which are resistant to various adverse conditions. 
Another somatic structure, the stroma, is formed as a mass of fungal cells that usually supports various 
types of reproductive structures. Rhizomorphs, sclerotia, microsclerotia and stroma are important struc-
tures in determining the type and, in some few instances, the identity of an unknown fungus. The more 
identifiable structures (mainly reproductive, but also somatic) that can be determined for an unknown 
fungus, the easier it will be to identify. 
The conidial cells, their conidiophores, acervuli, pycnidia, sporodochia, synnemata and chlamydo-
spores are other cellular structures of imperfect fungi which are easily discernible with the light micro-
scope, and are routinely used in identification. These structures are illustrated and discussed throughout 
this book. Complete familiarity with these structures will facilitate use of the keys for identifying 
unknown imperfect fungi. 
xvii 
FACTORS AFFECTING GROWTH AND 
SPORULATION OF I M P E R F E C T FUNGI 
The imperfect fungi are adapted to live under diverse environmental and nutritional conditions. 
Conidia of some species often survive for years in a cold or dry environment and germinate upon 
exposure to favorable conditions. The conditions that favor or inhibit growth and sporulation of a given 
fungus are correlated with its habitat. For example, Bispora, which obtains its nutrients from decaying 
wood, is limited in growth only by temperature and moisture, whereas, other fungi have more precise 
requirements, such as for living tissue or preformed vitamins. In fact, the dissemination of plant 
pathogenic conidia is often limited to the growing season of the host plant, and the production of conidia 
at that time. This and other types of adaptation have led to the survival of the deuteromycetes that exist 
today. Several types of fungal responses to nutrition and environment are presented. 
TEMPERATURE 
Temperature and moisture are universal factors that affect all organisms and must be favorable for 
them to survive, grow and reproduce. The cardinal temperatures i.e. minimum, optimum, and maximum, 
are used to describe the range at which individual imperfect fungi can grow. The exact ranges are 
influenced by other factors. There is a great variation among the responses to temperature of the 
imperfect fungi; however, they all produce some growth at mesophilic temperatures. When growing 
unknown, fungi it is best to select a temperature between 20 and 30 degrees Centigrade for their initial 
incubation. 
MOISTURE 
Imperfect fungi are capable of growing in liquid nutrient solutions provided that sufficient oxygen is 
present. However, many deuteromycetes can grow in the absence of liquid water. Botrytis cinerea and 
Penicillium expansum are plant pathogens which cause rots of plant parts and obtainmoisture from the 
decomposing plant cells. Species of Aspergillus, Penicillium, Cladosporium, and Aureobasidium are 
common decomposing agents of cloth, paper, leather, wood and even painted surfaces where there is no 
free moisture. Aspergillus and Penicillium spp. proliferate in stored grains when the moisture content is 
greater than 14%. Another Aspergillus sp., A, glaucas and its close relatives are well known for their 
ability to grow under conditions of severe physiological drought. 
In contrast there are the many imperfect species that cannot grow without liquid water or a saturated 
atmosphere. Spores of most deuteromycetes require moisture for germination. 
LIGHT 
Imperfect fungi respond to light (radiation) in a myriad of ways, but are not photosynthetic. Like all 
fungi they are incapable of reducing C02 to carbohydrate via radiation. Nevertheless, phototropic growth 
of conidiophores has been amply demonstrated for Aspergillus giganteus, A. clavatus, Penicillium 
claviforme and numerous other fungi. When cultures receive unilateral illumination, the conidiophores 
grow toward the white light, irrespective of the position of the culture. Certain frequencies of radiation 
are also known to enhance or be necessary for the induction of sexual structures of imperfects having 
known teleomorphic states. Radiation also may affect the chemical composition of media thereby 
promoting growth patterns different from those that would occur when the media were stored in the dark. 
xvlii 
Radiation has the greatest impact on sporulation of imperfect fungi. Sporulation of imperfects is either 
induced (i.e., light is necessary) or enhanced by exposure to different wavelengths of radiation. 
Ultraviolet, near ultraviolet, blue (most common), a wide band of blue-green-yellow and far red all affect 
fungal sporulation, albeit, quite differently. The red band is seldom effective for inducing sporulation. 
White light may be as effective as any given color if the intensity is nearly equal. The intensity of 
white light necessary for sporulation by Epicoccum nigrum varied inversely with duration of exposure. 
An exposure of mycelial cultures on agar to sunlight (7,000 ft. candles) for 15 minutes induced the 
production of about as many conidia as a single exposure of 24 hours at 50 ft candles or 6 hours at 100 ft. 
candles. Spores were produced only in the zone of young hyphae at the time of exposure. It is well 
known that ultraviolet radiation is inhibitory, yet there are few^ concrete examples of inhibition of 
imperfect fungi by visible light. Remember, when growing imperfects which do not sporulate in culture, 
the absence of light or too little of it, may be an important factor. In general, expose fungal cultures to 
alternating periods of light and dark to induce sporulation. 
HYDROGEN-ION CONCENTRATION (pH) 
Most fungi grow optimally when the substrate is slightly acid between pH 5.0 and 6.0. However, they 
will generally achieve fair to good growth over a much wider range, from about pH 3.0 to 8.0. Certain 
species are able to tolerate even greater ranges: Aspergillus niger, pH 2.8 to 8.8; A. oryzae, 1 . 6 to 9.3; 
PenicilUum italicum, 1 . 9 to 9.3; Fusarium oxysporum, 1 . 8 to 11.1; Botrytis cinerea, 2.8 to 7.4; and 
Rhizoctonia solani, 2.5 to 8.5. When fungi are growing on most culture media, they alter the pH of the 
substrate. The extent of the pH change depends on the composition of the substrate as well as on the 
genetics of the imperfect fungus. 
CARBON AND NITROGEN SOURCES 
The requirement of fungi for carbon is greater than any other nutrient, however a source of nitrogen 
must also provided. The ubiquitous nature of most deuteromycetes indicates that they possess the genetic 
determinants (synthesis of enzymes) to utilize carbon from many different sources; among these, 
cellulose is the most abundant utilizable source. Seldom does a fungus in nature encounter a pure carbon 
source, but rather will preferentially select from what is available. 
To determine the ability of specific fungi to utilize single carbon sources, experiments in the 
laboratory must be conducted under controlled conditions, using a medium that is complete for all 
nutrients except carbon. Imperfect fungi respond to different carbon sources, and their preferred source is 
usually associated with the niche they occupy in the ecosystem. Growth on glucose, fructose and 
mannose are approximately the same for all fungi. Most natural media have more than one carbon source 
from which a fungus can obtain carbon requirements for growth and reproduction. 
In nature, organic materials provide the nitrogen needed for growth; however, most fungi can use 
sources of inorganic nitrogen as well. Most imperfect fungi utilize nitrate, ammonium and amino acids as 
sources of nitrogen. Growth on inorganic nitrogen is often less than on a mixture of amino acids or on a 
complex organic nitrogen source. If one merely desires to cultivate deuteromycetes on a laboratory 
medium, yeast extract or casein hydrolysate is excellent. To study the relative rate of utilization of 
nitrogen sources, one should use single amino acids, such as asparagine, aspartic acid or glutamic acid. 
VITAMINS 
Most imperfect fungi are capable of synthesizing required vitamins from living or non-living 
substrates. Some imperfects, however, are deficient and cannot synthesize certain vitamins. Such 
deficiencies can be determined only by cultivation in suitable synthetic media with and without added 
vitamins. When imperfects are vitamin-deficient, it is usually thiamine that they are unable to synthesize. 
A deficiency may be single or multiple, complete or partial. Most species of Aspergillus synthesize all 
XIX 
required vitamins. Botrytis cinerea, species of Penicillium, Cylindrocladium scoparium, Gliocladium 
roseum and other imperfect fungi are also able to synthesize their vitamin requirements. The pycnidial 
producer, Dendrophoma obscurans, must have a preformed source of thiamine as do some species of the 
dermatophyte genus, Trichophyton. Biotin is needed for Diplodia macrospora and for Stachybotrys atra. 
INORGANIC SALTS AND MICROELEMENTS 
Natural organic compounds often furnish all of the inorganic salts necessary for growth. However, if 
one needs to culture imperfects on synthetic or semi-synthetic media, it is necessary to add certain 
compounds. Monobasic potassium phosphate (KH2P04) and magnesium sulfate (MgS04) will supply 
potassium, phosphorus, magnesium and sulfur. The microelements Fe, Zn, Mn, Cu and Ca are frequently 
added to synthetic media to supply additional inorganic elements needed for optimal fungal growth. 
ISOLATION, CULTURE MEDIA, MAINTENANCE OF STOCK CULTURES, 
AND PHYSIOLOGY 
Information on these topics can be found on pages 1-3. 
xx 
REFERENCES CITED 
1. Alexopoulus, C. J., C, W. Mims and M. Blackwell. 1996. Introductory Mycology. John Wiley & 
Sons, New York. 
2. Barron, G. L. 1968. The Genera of Hyphomycetes from Soil. Williams & Wilkins, Baltimore, MD. 
3. Buckley, P. M., T. D. Wyllie and J. E. DeVay. 1969. Fine structure of conidia and conidium 
formation in Verticillium albo-atrum and V. nigrescens. Mycologia61: 240-250. 
4. Farley, J. F., R. A. Jersild and D. J. Niederpruem. 1975. Origin and ultrastructure of the intra-hyphal 
hyphae in Trichophyton terrestre and T. rubrum. Arch. Microbiol. 43: 117-144. 
5. Griffiths, D. A. 1973. Fine structure of the chlamydospore wall in Fusarium oxysporum. Trans. Br. 
Mycol. Soc. 6 1 : 1-7. 
6. Grove, S. N. 1978. The cytology of hyphal tip growth, In: The Filamentous Fungi, (Vol. 3). Smith, 
J. E. and D. R. Barry, Eds. John Wiley & Sons, New York. 
7. Grove, S. N. and C. E. Bracken 1970. Protoplasmic organization of hyphal tips among fungi: 
Vesicles and Spitzenkorpers. J. Bacterio], 104: 989-1009. 
8. Howard, R. J. 1981. Ultrastructural analysis of hyphal tip growth in fungi: Spitzenkorper, 
cytoskeleton and endomembranes after freeze substitution.J. Cell Sci. 48: 89-103. 
9. Hughes, S. J. 1953. Conidiophores, conidia and classification. Can. J. Bot. 3 1 : 577-659. 
10. Hunter, B. B. and H. L. Bamett. 1973. Deuteromycetes (Fungi Imperfecti), In: Handbook of 
Microbiology: (Vol. 1), Organismic Microbiology. Laskin, A. I. and H. A. Lechevalier, Eds. CRC 
Press, Cleveland, OH. 
11. Hunter, B. B. and H. L. Bamett and T. P. Buckelew. 1978. Deuteromycetes (Fungi Imperfecti), In: 
Handbook of Microbiology: (Vol. 2), Fungi, Algae, Protozoa, and Viruses. Laskin, A. I. and H. A. 
Lechevalier, Eds. CRC Press, West Palm Beach, FL. 
12. Mims, C. W. 1991. Using electron microscopy to study plant pathogenic fungi. Mycologia 83:1-19. 
13. Newhouse, J. R„ H. C. Hoch and W. L. MacDonald. 1983. The ultrastructure of Endothia parasitica. 
Comparison of a virulent with a hypovirulent isolate. Can. J. Bot. 6 1 : 389-399. 
14. Newhouse, J. R., W. L. MacDonald and H. C. Hoch. 1990. Virus-like particles in hyphae and conidia 
of European hypovirulent (dsRNA-containing) strains of Cryphonectria parasitica. Can. J. Bot. 
68:90-101. 
15. Roberson, R. W. 1992. The actin cytoskeleton in hyphal cells of Sclerotium rolfsii. Mycologia 84: 
41-51. 
16. Roper, J. A. 1966. The parasexual cycle, In The Fungi, (Vol. 2). Ainsworth, G. C. and A. S. 
Sussman, Eds. Academic Press, New York. 
XXI 
PARTI 
PHYSIOLOGY 
ISOLATION 
Many different techniques for the isolation of fungi in pure culture have been described (246, 390). 
One should select and try first a method that is simple and easy, using a general purpose medium. Many 
species, especialJy common .saprophytic hyphomycetes, sporulate readily in a moist chamber on pieces of 
wood, leaves, or other plant pans. Conidia may be lifted from the sporulating conidiophores by touching 
with a small bit of agar on the tip of a needle, while looking through a stereoscopic microscope. This 
simple method often results in a high percentage of cultures free of contamination. It can also be used to 
obtain conidia from oozing acervuli or pycnidia. Species growing in habitats with an abundance of 
bacteria may require the use of dilution plates or antibiotic agar (219). A water agar substrate may even be 
useful, but a rose bengal streptomycin agar has been recommended (390). A highly specialized medium 
containing antibiotics was used for isolation of Vertirtcladiella procera from diseased pine roots (428). 
The use of geranium leaves placed on the soil surface has been recommended for recovering species of 
Cylindrocladium from soil (310). Botrytis cinerea and other soft rot fungi can be obtained easily in pure 
culture by passage through apples or other fruits. Pathogenic fungi within plant tissue often require 
surface sterilization with 10% chlorox for 2 minutes before plating the material on agar (246). The 
common method of obtaining the oak wilt fungus from diseased trees was stripping bark from twigs, 
dipping in 95% alcohol, and flaming (445). Wood chips were then plated on agar. 
The necrotrophic mycoparasites, such as Gliociadium roseum and species of Trichuderma, do not 
require a special medium for isolation. However, the biotrophic mycoparasites are a highly specialized 
group in regard to nutrition, are usually isolated with a host species, and are best maintained as two-
mem be red cultures. 
Nematode trapping fungi may often be obtained by placing a bit of horse manure or soil rich in 
humus on an agar plate. Nematodes are usually abundant after a few days and the trapping fungi, if 
present, should appear a few days later. Transfers from pure cultures of these species to the plates with 
nematodes will assure the formation of the characteristic loops, rings, or nets. Common species belong to 
the genera Arthrobutrys, Dactylella, Monacrosporium, or close relatives (106). 
Conidia of Bispora sp. Note the formation of a new 
conidium at the apex of the con i d i a l chain. 
A synnematous fungus (Briosia sp.) growing from 
decayed vegetation. 
1 
2 PHYSIOLOGY 
CULTURE MEDIA 
A satisfactory general culture medium must contain all of the nutrients required by the fungus: 
utilizable carbon and nitrogen sources, certain salts and microelements, and water. Some species are 
favored by added vitamins or growth factors. Many plant parts or products contain these nutrients but 
not always in quantities optimum for growth or sporulation. A potato-dextrose (glucose) agar medium 
has been the favorite of many plant pathologists for many years. Other natural media have been 
developed and used by mycologists for specific fungi. A list of one hundred media is given in the 
Mycological Guidebook (390). The authors prefer a general medium containing 5 to 10 g glucose, I to 2 g 
yeast extract, and 1000 ml water. Addition of agar and changes in concentrations may be made as desired. 
This medium is easy to make, and the pH need not be adjusted. 
The use of a synthetic medium, in which each nutrient and its concentration is known and can be 
altered as desired, is preferred in critical studies of fungus physiology. Such media can be duplicated 
exactly, and the effects of each nutrient can be measured. One satisfactory synthetic medium contains 
glucose (5 to 10 g), KN03 . asparagine or glutamic acid (1 to 2 g), KH2P04 (1.0 g), MgS04 (0.5 g), 
microelements (Fe, Mn, Zn) (trace), and distilled water (1000 ml). Vitamins thiamine (100 /jg). biotin (5 
fig), and pyridoxinc (JOO/ig) may be added routinely for the deficient species (259). This liquid medium 
may be used in flasks, or agar may be added for tube or plate culture, Five species of biotrophic 
mycoparasites require the new growth factor mycotrophein, which is a naturally occurring product in 
most filamentous ascomycetes and imperfects. It may be obtained in crude form by extracting from the 
mycelium with hot water (10, 12, 48, 138, 220,469). 
MAINTENANCE OF STOCK CULTURES 
The choice of a method for keeping viable cultures over a long period of time depends on the period of 
time they are to be maintained and the convenience of the method (259). Frequent transfer of mycelium 
from a culture to a fresh agar slant in test tubes is satisfactory for short periods. Long term maintenance of 
viable mycelium can be accomplished using screw-cap test tubes. Allow mycelium to grow until it reaches 
the edge of the agar slant, then screw the caps down tightly and store at about 5 UC. Transfer cultures after 
6 to 12 mo. The use of screw cap tubes has the additional advantage of excluding mites. Many eonidia 
remain viable for months when collected and stored dry at low temperatures, or simply frozen. Mycelium 
of some fungi may be cultured on bits of wood or other plant tissue and stored dry-
Fruiting structures of Cylindrocladium parvum growing in Conidial heads of Aspergillus niger. 
culture. 
PHYSIOLOGY 
PHYSIOLOGY: NUTRITION AND ENVIRONMENT 
See references 141, 157, 162, and 259 for textbooks on fungus physiology. 
The same nutrients that favor vegetative growth are also generally favorable to sporulation, but often in 
different concentrations or ratios. A low concentration of available carbon usually favors sporulation. 
Sporulation by species pycnidia is often delayed until growth reaches a maximum. 
Among the common carbon sources, glucose, fructose, mannose, and maltose are utilized most readify; 
xylose and sucrose intermediately; whereas lactose and sorbose are often poorly utilized or not at all. 
The table lists as examples the relative amount of vegetative growth of selected species on several sugars 
(3 = good to excellent; 2 = fair; 1 = poor; 0 = not utilized) (218). 
Alternaria solani 
Aspergillus niger 
Colletotrichum lindemuthianum 
Cordana pauciseptata 
Dendrophoma obscurans 
Helminthosporium sativum 
Penicillium expansum 
Rhizoctonia solani 
Thielaviopsis basicola 
Choanephora cucurbitarum 
A = days 
B = glucose, fructose, mannose 
C = galactose 
D = sorbose 
A 
14 
7 
14 
14 
14 
7 
4 
5 
7 
3 
B 
3 
3 
3 
3 
3 
3 
3 
3 
3 
3E = xylose 
F = maltose 
G = sucrose 
H = lactose 
C 
3 
2 
3 
3 
3 
2 
2 
3 
3 
3 
D E 
1 3 
2 3 
0 1 
0 3 
1 2 
1 2 
3 3 
0 3 
0 0 
0 I 
F 
3 
3 
2 
1 
2 
3 
3 
3 
3 
3 
G H 
2 2 
3 1 
2 2 
1 1 
2 2 
3 2 
3 1 
3 2 
3 0 
0 0 
Temperature is a universal factor affecting all physiological processes in fungi, most of which grow w 
within a range of 25 to 30 °C, but there is much variation. The approximate cardinal temperatures 
given below for selected species (218). 
Aspergillus fumigatus 
Botrytis cierea 
Diplodia zeae 
Epicoccum nigrum 
Helminthosporium sativum 
Humicola grisea v. thermoides 
Rhizoctonia solani 
Trichothecium roseum 
Verticillium albo-atrum 
Minimum 
<20 
0 
10 
< 5 
< 5 
24 
2 
<10 
5 
Optimum 
35 
20 
30 
25 
25-30 
38-46 
25-30 
30 
25 
Maximum 
50 
30 
35 
35 
35 
56 
35 
35 
35 
well 
are 
Visible white light may affect imperfect fungi in different ways. Some species show a decided positive 
phototropism of the conidiophores (e.g., Aspergillus giganteus, A. clavatus, and Penicillium claviforme). 
The conidiophores grow directly toward the source of light, regardless of the position of the culture (259). 
Sporulation of a number of species of imperfects is either induced (light is essential) or favored 
(increased) by exposure of the mycelium to radiation. In general, only the mycelium that is young at the 
time of exposure responds to radiation. Different species respond to different wave lengths, blue being the 
most effective range for most fungi. Some species that respond to exposure to white light or to specific 
wave lenghths are: Botrytis cinerea (uv), Cylindrocladium citri (blue to far red), Cyllndrocladium spp. (uv, 
near uv, blue), Dendrophoma obscurans (blue), some isolates of Epicoccum nigrum (uv), Helmintho-
sporium vagans (near uv), and Trichoderma lignorum (blue). The intensity of white light required to 
induce sporulation by one isolate of Epicoccus nigrum varied inversely with the duration (430). Note that 
a long exposure to intense ultraviolet radiation is lethal to fungus mycelium. 
3 
4 PHYSIOLOGY 
USE OF IMPERFECT FUNGI TO ILLUSTRATE BIOLOGICAL PRINCIPLES 
Certain species work well in demonstrating the effects of nutritional and environmental factors on 
growth and sporulation. A few demonstrations that can be easily performed in the classroom, together 
with the species used, are suggested below. 
Effects of white light on production of conidia: Trichoderma Ugnorum, Epicoccum nigrum (390). 
Inoculate plates of general purpose agar at the center with conidia or mycelium. Place some cultures in-
continuous light, some in alternate light and darkness, and some in total darkness at 20 to 25 °C. Examine 
after 4 to 6 days. E. nigrum may also be used to demonstrate an inverse intensity-duration relationship 
required for sporulation (i.e., long exposures at low intensity compared with short exposures at high light 
intensity (429). Try a range from 5 to 1000 footcandles. 
Positive phototropism of conidiophores: Aspergillus clavatus. Inoculate several plates of general 
purpose medium with conidia. Place some cultures beneath continuous light, some with single directional 
light, and some in total darkness. Wrap some in light-tight paper or foil, and cut one or two small 
windows. Examine after 4 or 5 days. 
Effect of color (wave length) of light on fruiting: Dendrophoma obscurans (32). Place cultures of this 
fungus under white light, under blue, yellow, green, and red filters, and in darkness. Examine after 7 days. 
Natural products may replace the light requirement for production of pycnidia: Dendrophoma 
obscurans. Use a synthetic agar medium with thiamine. Place on some plates autoclaved strawberry 
leaflets on the surface of the agar. Incubate cultures in alternate light (50 footcandles or more) and 
darkness for a few days, and examine for pycnidia. 
Special light requirements for production of conidia: Choanephora cucurbitarum (11). Use plates of 
glucose-asparagine agar plus thiamine. Petri dishes with loose-fitting lids will allow adequate aeration. 
Place cultures under the following conditions: continuous light; continuous darkness; 2 days light — 
12 hours darkness; 2 days darkness — 12 hours light. Examine for conidia in 3-day-old cultures. 
Need for adequate aeration for production of conidia: Choanephora cucurbitarum. This can be done 
simultaneously with the light requirement demonstration. Provide adequate aeration of some of the 
cultures by using loose-fitting lids, and prevent exchange of gases in other cultures by taping dishes closed 
(II). Incubate in alternate light and darkness. 
Sugar concentration affects growth of mycelium and production of conidia: Helminthosporium 
sativum, Choanephora cucurbitarum, or Mektnconium JuKgenium (or other species sporulating readily). 
Use a glucose-yeast extract medium, with glucose concentrations of 1, 5, 20, and 5 g/liter. 
Sugar concentration affects size of conidia: Helminthosporium victoriae (or some other species of this 
genus) (110). Prepare the same medium as above, and measure the length of conidia formed at the 
different concentrations. 
Thiamine deficiency: Dendrophoma obscurans or Choanephora cucurbitarum (11). Use a liquid 
glucose-asparagine medium (see section on media above) in small flasks (25-ml to 250-ml flasks are 
satisfactory). To half of the medium add thiamine at the rate of 1 0 0 //g/liter. Observe growth daily. If an 
accurate measure of growth is desired, the mycelium can be collected on a cloth or filter paper, dried and 
weighed. 
Biotin deficiency: Diplodia macrospora (259). Repeat above procedure, except use biotin at the rate of 
5 ^g/liter. 
Multiple deficiency for thiamine and biotin: Arthrobotrys musiformis. Use the same basal medium as 
above; add vitamins singly and in combination, using basal medium as control. 
Pyridoxine deficiency: Graphium sp. (9). Use the same basal medium as above, adding pyridoxine at 
the rate of 1 0 0 /ig/liter. 
PHYSIOLOGY 5 
Destruction of pyridoxineby Ijght(9): Graphiumsp. Preparea medium containing pyridoxine (liquid 
or agar). Store part of the medium under continuous bright light, and the remaining medium under total 
darkness for 10 to 14 days, Inoculate both media, and observe growth, 
Trapping and consuming small nematodes (106). Arthrobotrys spp. Use of a glucose-yeast extract 
medium is suggested. Nematodes can be obtained easily by placing a bit of horse manure on agar plates. 
After a few days use a stereoscope to check for the presence of Arthrobotrys. If none is present, use pure 
culture of fungus to inoculate cultures of the nematodes. Observe after a few days for rings, nets, or other 
traps and for trapped nematodes. 
Necrotrophic mycoparatism: Trichoderma lignorum, Gtiochdium roseum (10, 13). Prepare 
3- to 5-day-old cultures of several common fungi. Inoculate these cultures at the edge of the mycelium 
with one of the above suggested species. Observe daily for the parasite overgrowing the host colony, and 
examine microscopically for destroyed host cells. 
PART II 
TAXONOMY AND IDENTIFICATION 
THE SACCARDO SYSTEM OF CLASSIFICATION 
The Saccardo System has long been in use for the classification of imperfect fungi. The primary basis 
of this system is the morphology of the sporulating structures as they are known in nature, as well as the 
morphology and pigmentation of conidia and conidiophores. In artificial culture, some species of 
imperfects fail to form typical fruiting structures (e.g., acervuli. sporodochia. and synnemaia). 
Although an alternate system of classification may be more convenient for mycologists who have 
studied the different methods of conidium development, the authors recommend that others use the 
illustrations and key based on the Saccardo System. Moniliaceac and Dcmatiaceae, the two largest 
families, are presented according to the Hughes-Tubaki-Barron System of Classification beginning on 
page 41. 
ORDERS INCLUDED 
Conidia! Phycomycetes.Mycelium typically coenocytic; septa absent or infrequent; conidia (sporan-
gioles) present; typical large, muUispored sporangia may also be present in some genera. This group is 
included here because of similarity to some genera of the imperfect fungi. 
MUCORALES 8 
Mostly saprophytic, but some species parasitic on plants or other fungi. 
Fungi Imperfeeii. Mycelium (if present) typically septate with frequent septa; conidia normally present 
except in a few genera. Classification and identification are based on the conidial state, although the 
perfect state is often known and sometimes also present. 
Fruiting heads of Verticlciadielia procera. Synnemata and conidia of the Dutch elm fungus, Pesotum 
ulmi. 
6 
TAXONOMY AND IDENTIFICATION 7 
SPHAEROPSIDALES 28 
Conidia produced in well defined asexual fruit bodies, pycnidia. 
MELANCONIALES 33 
Conidia typically produced in acervuli under natural conditions; in culture conidiophores may 
be single or in compact groups, resembling sporodochia of the Moniliales. 
MONILIALES 
Conidia produced directly on the mycelium, on separate conidiogenous cells, or on distinct 
conidiophores that may be separate, in clusters, or in tightly packed groups. This is the largest 
and most common order. 
MYCELIA STERILIA 34 
No conidia produced. Usually sclerotia or other structures are formed for survival. This group 
does not include those fungi that do not sporulate because of unfavorable nutritional or 
environmental conditions. 
FAMILIES OF MONILIALES 
TUBERCULARIACEAE 25 
Condiophores typically compacted into a rounded or flat sporodochium, often not well developed 
in artificial culture. Some species of Melanconiales produce structures resembling sporodochia in 
culture. 
STILBACEAE 26 
Condiophores typically compacted into synnemata, which may be more abundant in aging 
cultures. Single conidiophores may also be present in some cultures or may be the only conidial 
state present. Such cultures may be identified in one of the following families. 
MONILIACEAE AND DEMATIACEAE 1 0 , 17 
Conidiophores mostly single and separate or produced in loose clusters. These two families are 
considered together because the only described difference is the hyaline conidia of the former and 
the pigmented (dark) conidia or conidiophores of the latter. Conidia are considered pigmented if 
the walls appear dark either separate or in mass. 
Only within this order (Moniliales) are families used in the identification of genera. 
In the Saccardo System orders and families may be broken into sections as follows: Amero-
sporae, conidia 1-celled; Didymosporae, conidia 2-celled; Phragmosporae, conidia with transverse 
septa only; Dictyopsorae, conidia with both transverse and oblique septations; Scolecosporae, 
conidia filiform; Staurosporae, conidia stellate or branched; Helicosporae, conidia typically 
coiled. The prefixes Hyalo- and Phaeo- are sometimes added to each section name to indicate 
hyaline or darkly pigmented conidia, respectively. r 
KEY TO GENERA 
Note that there is a separate key for each order. 
MUCORALES 
la Conidia (sporangioles) globose, borne singly on apex of conidiophores 
(sporangiophores) or branches Mortierella 60 
lb Conidia (sporangioles) globose to elongate, borne in clusters or in heads 2 
2a Special spore-bearing branches (sporocladia) bearing conidia only on one side 
(upper or lower) 3 
2b Sporocladia not present 7 
3a Sporocladia borne on coiled or recurved branches 4 
3b Sporocladia not on coiled or recurved branches 5 
4a Sporocladia on coiled branches; conidia short ellipsoid Spirodactylon 64 
4b Sporocladia in umbels on recurved branches; conidia obovoid Martensiomyces 64 
4c Sporocladia arising from loosely spiraled branches; conidia globose 
to subglobose Spiromyces 66 
5a Conidia borne only on upper (inner) side of sporocladium 6 
5b Conidia borne only on lower (outer) side of sporocladium Coemansia 62 
6a Conidiophore simple, bearing a few lateral or apical sporocladia Martensella 64 
6b Conidiophore simple, bearing a whorl of sporocladia on an apical disc Kickxella 64 
6c Conidiophore long, branched, bearing lateral, dome-shaped sporocladia Linderina 64 
7a Conidia produced in rows, or sporangioles in chains, often breaking up into rows 
of spores 8 
7b Conidia not in rows (chainlike); sporangioles do not break up into rows of spores 12 
8a Conidiophores nonseptate, simple or branched; conidia radiating apex 9 
8b Conidiophores septate, distinctly branched 10 
9a Conidiophores simple, with basal rhizoids Syncephalis 62 
9b Conidiophores usually branched; rhizoids absent Syncephalastrum 66 
10a Conidiophore branches dichotomous, all fertile Piptocephalis 62 
10b Conidiophore branches verticillate, all fertile Dimargaris 62 
8 
MUCORALES 9 
10c Conidiophore branches irregular, some with sterile tips 11 
1 la Fertile branches enlarged, bearing a head of cylindrical conidia Dispira 66 
1 lb Fertile branches repeatedly branched; conidia not in compact heads Tieghemiomyces 62 
12a Conidiophores with lateral or terminal branches 13 
12b Conidiophores simple 14 
13a Spore-bearing head compound; conidia ellipsoid, usually colored Choanephora 66 
13b Spore-bearing head compound; conidia hyaline, reniform to ellipsoid Radiomycea 64 
13c Spore-bearing head simple; conidia hyaline, globose to subglobose Cunninghamella 60 
14a Conidia not produced in slime, dry 15 
(4b Conidia produced in slime drop in a head Helicocephalum 60 
J 5a Conidia borne on enlarged globose apex Rhopalomyces 60 
15b Conidia borne on cylindrical upper portion of conidiophore Mycotypha 60 
MONILIALES 
la Conidia more or less coiled or spirally curved, hyaline or dark (parts of Moniliaceae, 
Dematiaceae and Tuberculariaceae) 2 
lb Conidia not coiled 
HELICOSPORES 
10 
2a Conidiophores forming a sporodochium 3 
2b Conidiophores single or in loose clusters 4 
3a Conidial coil flat; sporodochium stalked Everhartia 150 
3b Conidial coil in a loose spiral; sporodochium not stalked Hobsonia 150 
4a Conidial coil more or less flattened 5 
4b Conidial coil spiral 9 
5a Conidia thick in proportion to length 6 
5b Conidia slender 8 
6a Conidia hyaline or dark, with transverse septa only 7 
6b Conidia dark, with transverse and oblique septa Xenosporium 136 
C_7a /Parasitic on higher plants Helkomina 136 
7b Saprophytic on wood or bark Helicotna 136 
8a Conidiophores hyaline, short Helicomyces 136 
10 KEY TO GENERA 
8b Conidiophores pigmented, pale or dark, tall Helicosporium 136 
9a Conidia borne singly Helicoon 136 
9b Conidia catenulate Helicodendron 136 
NOT HEUCOSPORES 
10a Both conidia and conidiophores (if present) hyaline or brightly colored; conidiophores 
single or in loose clusters Moniliaceae 11 
10b Either conidia or comdiophores (or both) with distinct dark pigment; comdiophores 
single or in loose clusters Dematiaceae 105 
10c Conidiospores compacted into sporodochia Tuberculariaceae 202 
lOd Conidiophores typically united into synnemata Stilbaceae 225 
MONILIACEAE 
11a Conidia typically 1-celled, globose to several times longer than wide 12 
1! b Conidia typically 2-cellcd, mostly ovoid to cylindrical 62 
11 c Conidia typically 3- or more-celled, shape variable 74 
12a Conidiophores absent or like the mycelium, or reduced to phialidcs or peglike 
denticles 13 
12b Conidiophores distinct, although sometimes short 19 
V 13a Pathogenic to humans 14 
13b Saprophytic or parasitic, mostly soil or on plant parts 15 
14a Filamentous in cultures at 25°C, with large chlamydospores.. Blastomyces, Histoplasma 80, 82 
I4b Both filamentous and yeastlike cells at 25 °C, without large chlamydospores Candida 70 
15a Conidia (arthrospores) segment from branches of conidiophores, 
rounded Chrysosporium 68 
15b Conidia (arthrospores) formed by segmentation of hyphae, rod-shaped — Geotrichum , 68 
15c Conidia not arthrospores, not formed by segmentation 16 
16a Setae absent 17 
16b Setae present,mostly circinate, unbranched Circinotrichum 90 
16c Setae present, branched, circinate or wavy Gyrothrix 90 
17a Mycelium with clamp connections Itersonilia 70 
17b Mycelium without clamp connections 18 
18a Conidia produced on sterigmata and forcibly discharged Sporobolomyces 70 
18b Conidia borne on sides of mycelium or formed by budding, not forcibly 
discharged Candida 70 
MONIUALES 11 
19a Conidial state of powdery mildew; conidia catenulate Oidium 68 
19b Conidial state of powdery mildew; conidia not catenulate Ovulariopsis 70 
19c Not conidial state of powdery mildew , 20 
20a Conidia distinct in shape from apical cells of conidiophore 21 
20b Conidia (arthrospores) gradually become rounded from apical cells of 
conidiophore Wallemia 92 
20c Conidia (blastospores) globose to ellipsoid, similar to apical cells of 
conidiophore Monilia 72 
20d Conidia (blastospores) elongate, slender, much like cells of conidiophore Tilletiopsis 12 
21a Conidiophores (or phialides) typically simple or with few branches; phialides, if present, 
not tightly clustered into heads 22 
21b Conidiophores mostly branched; phialides, if present, clustered into groups or heads — 38 
22a Conidia catenulate 23 
22b Conidia not catenulate 29 
23a Conidia endogenous; phialides prominent, simple 24 
23b Conidia exogenous; conidiophores simple or branched 26 
24a Dark aleuriospores (chlamydospores) present, rounded, usually single Chalaropsis 90 
24b Dark aleuriospores (chlamydospores) in short chains of truncate cells, 
breaking up Ihielaviopsis 92 
24c Dark aleuriospores rarely formed 25 
25a Dark setae present Chaetochalara 90 
25b Dark setae absent Chalara 90 
26a Conidia blastospores or botryoblastospores 27 
26b Conidia otherwise 28 
27a Conidia in chains on slender conidiophores Hyalodendron 72 
27b Conidia on enlarged apex and nodes of conidiophores Gonatorrhodiella 78 
28a Conidia phialospores; phialides simple Monocillium 86 
28b Conidia arthropsores, nearly globose with a flat base Basipetospora 70 
28c Conidia arthrospores, rod-shaped Oidiodendron 68 
29a Conidiophores or conidiogenous cells short or indefinite Chrysosporium 68 
29b Conidiophores or conidiogenous cells distinct; fertile portion 
rachislikc Tritirachium, Beauveria 100 
29c Conidiophores or conidiogenous cells distinct, fertile portion not rachislike 30 
30a Conidiophores not inflated or only slightly so 31 
30b Conidiophores or fertile cells distinctly inflated at middle or apex 37 
12 K E Y TO GENERA 
31a Conidia curved; aquatic on dead leaves Lunulospora 138 
31 b Conidia globose to ovoid; not aquatic 32 
32a Conidia sympodulospores 34 
32b Conidia aleuriospores 35 
32c Conidia blastospores or phialospores; single 33 
33a Conidia blastospores, on long denticles, dry Otpitrichum 74 
33b Conidia phialospores, in moist heads 36 
34a Conidiophores clustered Ovularia 104 
34b Conidiophores single, separate Sporothrix 98 
35a Conidiophores single, simple, forked at apex Glomerularia 86 
35b Conidiophores usually have branches arising from an enlarged cell Umbelopsis 86 
35c Conidiophores with variable short lateral branches Staphylotrichum 80 
36a Conidiophores branched verticillately Vertkillium 92 
36b Conidiophores in acervuli in nature; in culture, conidiophores separate or in poorly 
formed groups Gloeosporium 188 
36c Conidiophores simple or with few branches, never in acervuli Cephalosporium 94 
37a Fertile cells globose; conidiophores short, stout Phymaiotrkhum 78 
37b Fertile cells globose, single, apical; conidiophores slender Oedocephalum 76 
37c Fertile cells globose, apical and intercalary Gonatobotrys 76 
37d Fertile cells somewhat elongated; conidia borne on short denticles Rhinotrichum 76 
37e Fertile cells somewhat elongated; conidia borne on long pegs or branches Acladium 76 
37f Fertile cells elongated, cylindrical, enlarged branches of conidiophorc; conidia on 
short denticles Chromelosporium 80 
38a Conidia in more or less compact heads; conidiophores simple 39 
38b Conidia not in compact heads; conidiophores simple or branched near the apex 41 
39a Conidia in dry heads Aspergillus 94 
39b Conidia held in heads of slime 40 
40a Simple diverging sterile arms subtending heads Gliocephalotrichum 94 
40b No sterile arms below conidial heads Gliocephalis 94 
4!a Conidia in basipetal chains 42 
41 b Conidial chains formed by segmentation of cells or branches of conidiophore 44 
MGNIHALES 13 
41 c Conidia not catenulate 45 
42a Conidiophores usually separate, not in columns or cushions 43 
42b Conidiophores and conidia in tall aggregates Metarrhizium 94 
42c Conidiophores and conidia in slimy cushions Myroihecium 146 
43a Conidia phialospores; phialides divergent, loose Paecihmyces 94 
43b Conidia phialospores; phialides upright, brushlike Pemcillium 94 
43c Conidia annelospores Scopulariopsis 98 
44a Arthrospores barrel-shaped, separated by prominent slender cells Amblyosporium 68 
44b Arthrospores rod-shaped to globose, separating cells not prominent Oidiodendron 68 
45a Rough-walled aleuriospores (chlamydospores) present 46 
45b Rough-walled aleuriospores absent 48 
46a Aleuriospores 1-celled, with attached hyaline cells Stephanoma 82 
46b Aleuriospores 1 -celled, smooth walled Botryoderma 86 
46c Aleuriospores 1-celled, rough walled, without attached cells Sepedonium 82 
46d Aleuriospores 2-celled; apical cell large, rough, basal cell small, smooth 47 
47a Phialospore state verticillate (like Verticillium) Mycogone 82 
47b Phialospore state aspergilliform (like Aspergillus) Chlamydomyces 82 
48a Conidia produced at or near apex of phialides or branches of conidiophores 49 
48b Conidia attached both at apex and side of conidiophore or its branches 57 
49a Larger conidiophores (at least) verticillate 50 
49b Branches of conidiophores irregular, not verticillate 51 
50a Phialospores in mucilaginous clusters Verticillium 92 
50b Sympodulospores in dry clusters Calcarisporium 102 
51a Conidia not aggregated in slime drops 52 
51 b Conidia held in heads by slime drops 54 
52a Conidia abundant, borne on inflated apical cells 53 
52b Conidia single or in small clusters, not on inflated cells 55 
53a Conidiophores tall, with one (or few) central axis and several equal, 
lateral branches Botryosporium 76 
53b Conidiophores tall, with irregular branches Botrytis 76 
53c Conidiophores tall, with regular dichotomous branching Dichobotrys 78 
53d Conidiophores short, with few branches Phymatotrichum 78 
54a Conidiophore branches brushlike, similar to Peniciltium Gliocladium 92 
14 K E Y TO GENERA 
54b Conidiophore branches spreading, not brushlike Trichoderma 92 
55a Conidiophore branches loose, conidia present 56 
55b Reproductive structure compacted, globose or pyramidal, bearing globose 
cells but no true conidia Cristulariella 74 
56a Saprophytic on leaves Hansfordia 98 
56b Saprophytic on wood; conidial state of Hypoxylon Nodulosporium 100 
57a Fertile portion of conidiophore (or sporogenous cell) zig-zag rachishke 58 
57b Fertile portion of conidiophore (or cell) not zig-zag, or rachislike 60 
58a Conidiophores simple or verticillately branched 59 
58b Conidiophores irregularly branched Geniculosporium 100 
59a Conidiophores bulbous at base; parasitic on insects Beauveria 100 
59b Conidiophores slender, not bulbous; not parasitic on insects Tritirachium 100 
60a Conidia borne on short denticles 61 
60b Conidia apical on branches, not on denticles Botryoderma 86 
6!a Conidiophores slender, with slender branches from main axis; 
not dichotomous Calcarisporium 102 
61b Conidiophores slender to stout; fertile cells somewhat inflated Chromelosporium 80 
62a Conidiophores well developed, branched 63 
62b Conidiophores mostly simple or with few branches 66 
62c Conidiophores none, reduced to cells of stroma Rhynchosporium 108 
63a Conidia ovoid to oblong 64 
63b Conidia (sympodulospores) obovoid Genicularia 110 
63c Conidia(phialospores) slender, cylindrical Cylindrocladium 108 
64a Conidiophore branches restricted to apical region Candelabrella 110 
64b Conidiophore branches not restricted to apical region 65 
65a Conidia in loose moist clusters Diplosporium 108 
65b Conidia in loose tangled chains Cladobotryum 108 
66a Apical cell of conidium much larger than basal cell 67 
66b Conidial cells not differing greatly in size 70 
67a Aquatic on submerged leaves Heliscus 108 
67b Not aquatic 68 
68a Both cells of conidium smooth walled Genicularia 110 
68b Apical cell of conidium rough walled; basal cell smooth 69 
MON1LIALES 15 
69a Microconidial state, if present, similar to Aspergillus Chlamydomyces 82 
69b Microconidial state, if present, similar to Verticiltium Mycogone 82 
70a Conidiophores single, not clustered; mostly saprophytic 71 
70b Conidiophores clustered; parasitic on leaves 73 
71a Conidia borne singly on short pegs or denticles at or near apex of comdiophore 72 
71 b Conidia borne successively at pointed apex of comdiophore Trichothecium 108 
72a Conidiophores tall, slender; conidia obovate to oblong Arthrobotrys 110 
72b Conidiophores short; conidia cylindrical to clavate Dactylaria 110 
73a Conidia cylindrical, often in short chains Ramularia 110 
73b Conidia ovoid to oblong, not catenulate Didymaria 110 
74a Conidia long, cylindrical, often bent or curved; aquatic 75 
74b Conidia shorter or not cylindrical; aquatic or not 76 
75a Conidiophores branched near apex; conidia 1 - or few-celled Flagelhspora 138 
75b Conidiophores simple; conidia single, apical Anguillospora 140 
76a Conidia 2- to several-celled, phragmosporous, not branched 77 
76b Conidia branched, staurosporous 84 
77a Causing dermatomycoses of man or animals 78 
77b Saprophytic or parasitic on plants 79 
78a Macroconidia clavate, rounded at apex Trichophyton 116 
78b Macroconidia spindle-shaped to ellipsoid Microsporum 116 
79a Macroconidia typically curved, pointed (canoe-shaped), 
small conidia usually also present Fusarium 130 
79b Other than in macroconidia, not canoe-shaped 80 
80a Conidiophores short, mostly simple or with few branches 81 
80b Conidiophores tall, simple or branched 85 
81 a Conidia cylindrical, mostly straight, or slightly curved 82 
81 b Conidia ellipsoid or long attenuated 83 
82a Conidia catenulate; conidiophores clustered Septocylindrium 128 
82b Conidia not catenulate (sympodulospores); conidiophores single Scolecobasidium 114 
82c Conidia not catenulate (phialospores); conidiophores single Cylindrocarpon 130 
83a Conidia ellipsoid, rounded at apex Fusoma 116 
83b Conidia cylindrical to filiform 84 
16 KEY TO GENERA 
84a Conidium with apical appendage Spermospora 128 
84b Conidia without appendages Cercosporella 128 
85a Conidiophores mostly simple, seldom branched 86 
85b Conidiophores typically branched 95 
86a Parasitic on grasses Pyricularia 128 
86b Saprophytic or parasitic on nematodes 87 
87a Middle cell of conidium greatly enlarged Monacrosporium 118 
87b Middle cell only slightly or not at all enlarged 88 
88a Conidia ovoid to clavate to cylindrical Dactylaria 110 
88b Conidia fusiform to cylindrical Dactylella 128 
89a Branches of conidiophore (phialides) verticillate Dactylium 130 
89b Conidiophores terminating in penicilliate branches Cylindrocladium 108 
90a True staurosporous conidia formed 91 
90b No true conidia known; "conidial" branches forming a well defined globose or conical 
structure, similar to a loosly formed sclerotium Cristulariella 74 
91 a Conidiophores reduced, not evident Thallospora 142 
91b Conidiophores distinct, well formed, length variable 92 
92a Conidial branches not greatly divergent 93 
92b Conidial branches widely divergent 94 
93a Conidial branches typically 2-pronged Dicranidion 138 
93b Conidial branches typically 3-pronged Tridentaria 140 
94a Central cell of conidium much enlarged 95 
94b Central cell of conidium not enlarged 97 
95a Conidia pyriform or clavate, with 3 slender branches Clavariopsis 140 
95b Conidia with central globose cell and 4 to 5 slender branches Actinospora 140 
95c Conidia with 3 to 4 broad cells in main axis and 2 to 4 slender appendages 96 
96a Conidial appendages attenuated, pointed Ingoldia 138 
96b Conidial appendages not distinctly attenuated CuHcidospora 140 
97a Conidia borne on phialides or phialide-Iike branches of the conidiophore 98 
97b Conidia borne otherwise 99 
98a Conidium with elongated axis and 2 lateral branches arising side by side Alatospora 142 
98b Conidium with 4 divergent branches arising near base of conidium Lemonniera 138 
MONILIALES 17 
99a Conidial branches formed one at a time 100 
99b Conidial branches formed simultaneously 103 
100a Conidial branches 4 or more 101 
100b Conidial branches 3 or less 104 
101a Main axis of conidium broader than branches Tetracladium 140 
101b Main axis of conidium about the same width as branches 102 
102a Number of branches variable mostly arising from one side 
of main axis Varicosporium 138 
102b Conidial branches dendroid, not limited to one side of main axis Dendrospora 140 
103a Conidial branches arising from different levels Tricladiutn 138 
103b Conidial branches arising from base of central axis Triscelophorus 138 
104a Conidial branches arising from near apex of main axis Articulospora 142 
104b Two conidial branches arising about midway of slender axis Tetrachaetum 140 
DEMATIACEAE 
105a Conidia typically 1-celled 106 
105b Conidia typically 2-celled 145 
105c Conidia typically 3- or more-ceiled phragmospores 156 
105d Conidia typically 3- or more-celleddictyospores 184 
106a Conidiophores absent or, if present, often poorly developed, consisting of 
1 to few cells 107 
106b Conidiophores mostly tall and well developed, cells distinct from conidia, 
simple or branched 122 
107a Blastospores borne directly on sides of mycelium, budding freely Aureobasidium 70 
107b Dark globose cells of the mycelium breaking up to form 1- to several-celled 
segments; conidiophorelike structures may also be present Torula 74 
107c Conidia appearing as blastospores, not budding, broadly ovoid to lenticular, 
with a hyaline slit on one side Papularia 82 
107d Conidia other than blastospores, not normally budding; conidiophore cells 
usually distinct but short 108 
108a Conidiophores extending slightly in length; conidia formed as meristem 
arthrospores Wailemia 92 
108b Conidia other than arthrospores 109 
109a Conidia formed as aleuriospores 110 
109b Conidia formed as phialospores, sympodulospores, or annellospores 114 
110a Conidia globose Ill 
18 KEY TO GENERA 
I !0b Conidia ellipsoid or pointed at apex 1 1 2 
II la Conidia black and shiny, borne singly, apically on a special flat 
hyaline cell Nigrospora 82 
11 lb Conidia apical, brown, not on a flat special cell Humicola 84 
11 lc Conidiophore reduced to one cell; conidia single, with a hyaline germ pore 
on one side Gilmaniella 84 
11 Id Conidia single on short branch; no germ pore evident; 
dark setae present Botryothchwn 84 
112a Conidia rough-walled, pointed at apex Echinobotryum 84 
112b Conidia smooth-walled, ellipsoid 113 
113a Conidiophores short, hyaline, repeatedly branched Wardomyces 84 
II 3b Conidiophore branches few; conidia borne on slender stalks Asteromyces 84 
113c Conidiophore branches few; conidia sessile; germ slit evident on one side Mammaria 84 
I I4a Conidiophores separate; sympodulospores hyaline, somewhat curved Idriella 102 
114b Conidiophores compacted into stromalike layers; sympodulospores 
dark, pointed at apex Fusicladium 112 
114c Conidiophores compacted into stromalike layer; annellospores dark, 
pointed at apex Spilocaea 106 
1 1 4 d Conidia formed as phialospores 1 1 5 
115a Conidia slightly curved, narrowly ellipsoid; simple curved setae present.. Circinotrichum 90 
U5b Conidia slightly curved, narrowly ellipsoid; branched, curved setae present. . . Gyrothrix 90