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The Basics of  Mycology & The Fungi

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True Fungi (Eumycophyta) 1

Basidiomycota (Basidiomycetes, Basidiomycotina) -- Higher fungi

Homobasidiomycetes

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                                                                                                                                                 Tables     Plates

 

Class:  Basidiomycota (Basidiomycetes,

     Basidiomycotina) -- higher fungi

    Sub-Class:  Heterobasidiomycetes

 

              Order:  Uredinales (Rusts)

                Family:  Pucciniaceae

                Family:  Melampsoraceae

 

             Artificial Group:  Uredinales Imperfecti

 

              Order:  Ustilaginales (Smuts)

                Family:  Ustilaginaceae

                Family:  Tilletiaceae

 

              Order:  Auriculariales

                Family:  Auriculariaceae

                Family:  Septobasidiaceae

 

              Order:  Tremellales

                Family:  Tremellaceae

 

              Order:  Dacryomycetales

                Family:  Dacryomycetaceae

 

Sub-Class:  Homobasidiomycetes (Holobasidiomycetes; Autobasidiomycetes,

   Eubasidiomycetes)

    SERIES:   Hymenomycetes

 

              Order:  Agaricales

                Family:  Exobasidiaceae

                Family:  Clavariaceae

                Family:  Hydnaceae

                Family:  Polyporaceae

                Family:  Boletaceae

                Family:  Agaricaceae

 

    SERIES Gasteromycetes

 

              Order:  Hymenogastrales

              Order:  Hysterangiales

              Order:  Lycoperdales

              Order:  Sclerodermatales

              Order:  Phallales

              Order:  Nidulariales

 

Bibliography    Sample Examinations

 

 

Introduction

 

          The Homobasidiomycetes is a large group that includes most forms of well-known fungi.  Due to their large size the fruiting bodies of these fungi are familiar to those who have an interest in living organisms. They are predominantly saprophytes and not one is obligately parasitic.  With rare exception these forms produce conspicuous basidiocarps.Included are the mushrooms, shelf fungi, coral fungi, puffballs, earthstars, stinkhorns and bird's nest fungi. 

 

          The basidia differ from the Heterobasidiomycetes in being primarily non-septate (some rare exceptions).  They resemble asci, and during their formation initially there are two nuclei which fuse.  Four spores are formed apically on sterigmata, which are in most cases forcibly discharged or the spores may be sessile on the basidium.  Basidiospores NEVER  BUD, nor do they ever become septate.

 

         Two series are designated:  Hymenomycetes and Gasteromycetes.  The Hymenomycetes have a well-defined hymenium of basidia, which are often accompanied by sterile structures and cystidia.  The hymenium is exposed prior to maturation of spores.  On the other hand, in the Gasteromycetes there is usually no well-defined hymenium and spores are never exposed until they are mature.

 

Characteristics of The Subclass Homobasidiomycetes

 

          The life cycles are similar in pattern throughout this group of fungi.  There are no sexual structures and there is a very prominent dikaryophase where the basidio9carps are built.  Basidiospores do not bud, but they do give rise to a monokaryotic mycelium.

 

          Many species are heterothallic.  Two monokaryotic mycelia which are compatible must initiate the dikaryophase:

 

Monokaryotic mycelium-1}

                                                                                                                       }   = Dikaryotic mycelium

Monokaryotic mycelium-2}

 

          The dikaryotic mycelium may persist for over 100 years and is an absorptive dikaryophase.  Over 95 percent of all hyphae are in the dikaryotic condition.  Clamp connections are restricted to the dikaryotic mycelium and are most characteristic of the Homobasidiomycetes.  Basidiocarps usually arise from rhizomorphs.

 

 

                    The Dikaryophase is initiated when the monokaryotic mycelium of one type contacts a monokaryotic mycelium of another type.  Hyphal anastomosis forms the dikaryophase.

 

 

          The dikaryophase is spread to other cells of the mycelium by a division of the two nuclei with the subsequent migration through septal pores of the daughter nuclei.  This continues from cell to cell until the entire mycelial network is in the dikaryophase.  After the dikaryophase has been reached the new growth will form clamps, which is also an indication of the completion of the process.

 

          Oidia are produced in a sticky matrix on small stalks, which branch out from the mycelium.  They are conidial in function and also may function in dikaryotization.

 

 

          Insects transfer the oidia to another mycelium.  If this mycelium is monokaryotic the nucleus of the oidium will pass into the hyphal cell, which sets up a dikaryophase.  Oidia are usually formed on a monokaryotic mycelium, but they may also be produced by a dikaryotic mycelium, in which case they are still monokaryotic themselves.

 

 

          In the "Buller Phenomenon" a dikaryotic mycelium dikaryotizes a monokaryotic mycelium.

 

 

          Clamp Formation occurs only in new growth (Fig. 401):

 

 

          There is predominantly a tetrapolar type of compatibility:

 

AB, Ab, aB, ab

 

          AaBb is the final combination required (only AB + ab and Ab + aB are compatible.  There is a Geographic Race Phenomenon where all isolates are fertile with every other isolate when the isolates are taken from separated geographic areas.  A couple of meters are sufficient separation in some cases.

 

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          The Series Hymenomycetes, Order Agaricales is the largest in the Basidiomycota and one of the largest in the entire fungal kingdom.  It includes many of our most familiar fleshy fungi.  In all cases there is a well-defined hymenium that consists of closely-packed basidia, often accompanied by paraphyses and sometimes by larger sterile structures known as "cystidia".  The different families are separated primarily on the form of the fructification and on the position in which the hymenium is located.  For example, the covering of the surface of "gills", lining tubes, extending over the surface of tooth-like projections, etc.  The families do intergrade to some extent.  On the whole, however, the family lines are fairly sharp and little difficulty is encountered in assigning most species to the proper group.

 

          A majority of the Agaricales leads a purely saprophytic existence, but a few are also aggressive parasites, and some are involved in mycorrhizae.  Very few members of this large assemblage are known to have a conidial stage.

 

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          Characteristics of the Agaricales are shown by the following six families:

 

          Exobasidiaceae is the only family treated here that has no fruiting body.  Species are parasitic on plants and form no basidiocarp. There is a naked palisade-like hymenium on the host surface, and great hypertrophy is induced, which is similar to that found in genus Taphrina of the Ascomycetes..

 

          Thelephoraceae species are bracket-like, the hymenium being spread on the smooth undersurface.  One genus mimics a cup fungus here, although the hymenium is on the outside of the cup.  The basidiocarp varies from a very thin and delicate basal weft of hyphae supporting the basidia to a well-developed fruiting body.  The most common type of fructification is a tough, leathery or corky structure, which is crust-like, shelf-like or upright with the hymenium always spread over a smooth, even or undulating surface.  Most species of this family grow on wood.

 

          Clavariaceae (Coral Fungi) species have a fleshy or waxy texture.  There is an upright and often branching fruiting body with a hymenium.  The common name of "Coral Fungi" derives from the beautiful compact branching form exhibited by many species.  However, some are less spectacular, having only simple club-shaped or slender columnar basidiocarps.  The texture of these fructifications is generally fleshy or waxy, and most of them tend to decay rapidly.  The hymenium extends over the whole surface of the fructification except at the base, which may be considered a poorly differentiated stalk.  Old decayed wood is a common habitat of most species of Clavaria, the most important genus in the family.

 

         Hydnaceae (Tooth Fungi) have downward projecting "teeth."  Some mimic mushrooms, but they have teeth instead of gills or pores.  These "teeth" are usually projected downward.  The hymenium forms a coating over the teeth.  A very great range is found in the form and texture of the fructifications.

 

         Polyporaceae (Pore Fungi) have species where the basidia line the tubes or pores.  This is the most important of wood-destroying fungi.  In the genus Fomes the perennial fruiting body adds a new layer of pores below the old one every year.  The name "Pore Fungi" comes from the fact that their hymenia line the numerous tubes or pores that are found on the underside of the fructification.  The basidiocarps are mostly corky or woody in texture and usually bracket-like in form, although some are resupinate and others consist of a stalk and pileus.  The great capacity of members of this family to disintegrate wood makes them both highly beneficial and highly damaging organisms.  A few species attack living tissue in standing trees.

 

         Boletaceae species were once included in the Polyporaceae as they have a stalk and a cap similar to a gill fungus.  Beneath the cap is found a layer of tubes that is easily pulled away from the rest of the fructification.  Fruiting bodies of most species occur on the ground in forests.  Many species are mycorrhizal fungi and certain species are regularly found only beneath certain kinds of trees, especially the conifers.  In autumn they occur all over North America from sea level to over 3,000 meters in moist mountain areas.  Most species are edible and generally safe to harvest.  Drying enhances their flavor when added to stews, soups, etc.  In America the cap is usually covered by a skin that is removed for consumption, while in humid areas of Central Europe this skin is not pronounced.

 

         Agaricaceae (Gill Fungi) There are over 100 genera and 6,100 species known, many of which have an excellent flavor.  A few are aggressive parasites on seed plants, some are undoubtedly mycorrhizal but most appear to be saprophytes on vegetable matter in the field and on the forest floor.  A few species may be found on wood.  The basidiocarp usually consists of a stalk and cap (pileus) and is usually very fleshy in texture and hence decomposes rapidly.  However, a few members of the family have more durable, leathery fructifications, and a few have basidiocarps that are bracket-like in form.  In all cases there are radiating gills or "lamellae" on the underside of the fructification, and the hymenium spreads almost evenly over the gill surface.

 

          A Key to some of the common genera of Agaricaceae is presented in Plate 232.

 

          The "Field Mushroom," Agaricus campestris has been cultivated for over 260 years and which today forms the basis for the substantial mushroom-growing industry.  In the search for wild mushrooms used for human consumption the genus Amanita is of special concern, for this includes several species whose fruiting bodies are deadly poisonous.

 

          The basidia are borne on radiating gills.  Paraphyses and cystidea occur on the hymenium together with the basidia.  The cystidea play a part in spreading the gills initially.

 

 

          The Life Cycle of the Agaricaceae is diagrammed as follows in Fig 404:

 

 

          Further details in the developmental cycle of the Agaricaceae may be viewed in Fig. 403 as follows:

 

 

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Please see following plates for Life Cycles and Structural characteristics in the Agaricales:

 

Basidiomycota:  Homobasidiomycetes:  Agaricales

 

Plate 163 = Oidiophore: Coprinus lagopus.

Plate 179 = Hymenium of a polypore.

Plate 178 = Structures of Exobasidium vaccinii.

Plate 180 = Agaricaceae (Agaricus spp.) Basidiocarp.

Plate 181 = Agaricaceae (Amanita spp.) Basidiocarp

Plate 182 = Trama:  With & without sphaerocysts.

Plate 232 = Key to Genera Of The Agaricaceae

Plate 233 = Example Structures:  Agaricales:  Polyporaceae & Boletaceae

Plate 234 = Example Structures:  Agaricales:  Hydnaceae & Clavariaceae

Plate 235 = Example Structures:  Agaricales:  Thelephoraceae & Exobasidiaceae

Plate 236 = Example Structures:  Agaricales:  Agaricaceae

 

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          The Series Gasteromycetes, Order Agaricales differs from the Hymenomycetes in that there is usually no well-defined hymenium, the basidia are produce din an enclosed structure or structured in the fruiting body, which does not open up until the spores are fully mature.  Most of the about 1,000 known species are saprophytes.  On the other hand, the Hymenomycetes have a well-defined hymenium with paraphyses and cystidea, and the basidiospores are always exposed prior to maturation.  In the Gasteromycetes the sporophores (basidiocarps) of most species eventually open by a pore or by regular or irregular rupture of the peridium.  However, in some cases the spores are imprisoned until the fruiting body decays or is consumed by animals.  Some subterranean forms depend on rodents and insects for spore release and dispersal.

 

          There are six orders:  Hymenogastrales, Hysterangiales, Lycoperdales, Sclerodermatales, Phallales and Nidulariales.  The Hymenogastrales and Hysterangiales are known as the "False Truffels."

 

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          The order Hymenogastrales includes species that are intermediate in structure between the Hymenomycetes and Gasteromycetes.  A well-known genus is Endoptychum, E. agaricoides being common in North America.  Its fructifications are stalked and somewhat resemble mushrooms.  A sterile columella is a main feature of many species.

 

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          The order Hysterangiales contains a group of fungi that are known as the "False Truffels."  Further treatment of this group will be forthcoming at a later date.

 

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          The order Lycoperdales includes the "Common puffballs".  The peridium is always two-layered in this order, but may be difficult to discern.  The gleba takes up the entire interior portion of the fungus where there are many global chambers.  The hymenium lines each cavity, and later the spores are released into the global chamber.  The tissue, which separates the global chambers, breaks down into capillitial threads.  The spores escape through an apical pore.

 

 

          The Genus Gaster includes the "Earth Stars."  The two peridia are very conspicuous and the outer peridium is the thickest.  At maturity, the outer peridium bends back leaving only the inner peridium to cover the gleba.  This then has the appearance of a star.

 

 

          The Genus Calvatia includes the "Giant Puffballs."  Some species are of remarkable size, and 15-10 kilos may be attained.  There is no apical pore and the glebal mass is exposed gradually as the peridium flakes off.

 

          The Genus Bovista has dark spores and a capillitium.  The fruiting body bumps along the fields with wind currents.

 

          The Genus Tylostoma includes the "Stalk Puffballs."  These fungi are usually found only in sandy soils.

 

 

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Please see following plates for Structural characteristics in the Lycoperdales:

 

Basidiomycota:  Homobasidiomycetes:  Lycoperdales

 

Plate 237 = Example Structures:  Gasteromycetes:  Lycoperdales

 

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          The order Sclerodermatales includes the "Hard Puffballs."   They are partially hypogean (= growing below the ground).  The basidiocarp has a single-layered peridium and there is no hymenial lining to the chambers inside the peridium.  Hyphae grow into the center, which produces the basidia.  The skin-like wall is the peridiolum and it surrounds each chamber that is considerably larger than those in the Lycoperdales.  There are never any capillitial threads and the spores are released by irregularly breaking off of the peridium.  There are no pores ever developed.  Root-like cables of hyphae occur at the base of the fruiting body.

 

          In the Genus Pisolithus there is a marked development of the root-like basal portion.

 

 

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Please see following plates for Structural characteristics in the Sclerodermatales:

 

Basidiomycota:  Homobasidiomycetes:  Sclerodermatales

 

Plate 238 = Example Structures:  Gasteromycetes:  Nidulariales & Sclerodermatales

 

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          The order Phallales has the notable distinction of possessing a disagreeable odor for which they have received the common name of "Stinkhorns".  A foul-smelling fluid forms as a result of the breakdown of paraphyses.  In the Genus Ithyphallus (Phallus) development begins underground, which is the "egg stage."

 

 

          There is a rapid elongation of the central core to form a stalk.  The entire structure is then above the ground.  The receptacle may be reticulate and the global mass breaks down into a greenish-brown, disagreeable fluid, which is attractive to insects.

 

 

          The Genus Dictyophora has an indusium, which is formed from a third core layer.

 

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Please see following plates for Structural characteristics in the Phallales:

 

Basidiomycota:  Homobasidiomycetes:  Phallales

 

Plate 239 = Example Structures:  Gasteromycetes:  Phallales

 

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          The order Nidulariales includes the "Birds Nest Fungi."  These fungi are coprophilous or they occur on wood.  Their fruiting bodies are very small and there is a well-marked peridiola.  The Genus Cyanthus has a lightly covered peridium on the apex, which is known as the epiphragm.  The fenicular thread is a cable-like structure that attaches the peridiolum to the peridial wall.  The epiphragm breaks down to reveal the "nest" with "eggs."

 

 

          Peridiola are either splashed out of the "nest" by rain or are shot out by their fenicular threads.  These threads hook onto the nearby branches and the peridiola remain pendant and sway in the wind.  Spores may not be released for some time thereafter.

 

          The fruiting body of species of the Genus Sphaerobolus is only 2 mm. in diameter.  They are found on wood and the peridium is made-up of two layers.  These serve to throw-out the peridiola for up to 5-6 meters!  The inversion of the peridia throws out the peridiolum.

 

 

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Please see following plates for Structural characteristics in the Nidulariales:

 

Basidiomycota:  Homobasidiomycetes:  Nidulariales

 

Plate 183 = Structure of fruiting body:  Cyathus striatus.

Plate 184 = Splashing of peridiole:  Cyathus striatus.

Plate 238 = Example Structures:  Gasteromycetes:  Nidulariales & Sclerodermatales

 

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Bibliography

 

◄Introduction                                                                                                                                                               Fungi Imperfecti ►