Naming and Classification of Fungi
Although it is something that we give little thought to, the naming and classification of objects play an important role in society. Imagine the problems that we would have if we were not given names and if we did not name our cities, streets or pets. Now imagine if we did not classify the books that are in our libraries, tools in hardware stores, video tapes in video stores, etc. Without names for objects and a system to classify them, it would be impossible or at least be very difficult to organize, categorize and find information for which we are searching. It should not be a surprise then that there is a discipline in biology called taxonomy that studies the classification and naming of organisms. Presently, there are approximately 1.5 million species of organisms that have been described by biologists and each year thousand of new species are described by science. It is estimated that the total number of species may range from 5 to 30 million. With such a rich diversity of life on this planet, naming and classifying this many organisms would be a difficult task, to say the least. However, such a system must be constructed if our knowledge in biology is to advance.
The job of the taxonomist is a difficult one. The general public thinks of them as snobbish because they refer to organisms with "fancy names". The reputation of the taxonomist is often not regarded in high esteem even among scientist because of its descriptive rather than experimental nature. Christensen (1961), a well respected mycologist-plant pathologist, describes taxonomist as "those who spend their time putting living things into pigeonholes, a low but necessary form of scientific endeavor". The lay person often wonders why taxonomist must refer to onions as Alium cepa or leopards as Panthera pardus. However, they are not using these names just to impress you or to make themselves feel more important in the eyes of their colleagues. Instead, they are merely identifying organisms by their scientific or species name. The species name is called a binomial, which consists of two parts. The first part is the genus (plural: genera) and the second is the specific epithet. For example, the species name for the human animal is Homo sapien. When written, the species name is emphasized by italicizing or underlining the binomial. Each known species, once it has been described by science, is given a unique species name. Another words, there is only one valid scientific name that is unique to a species regardless of where it may may be found. This differs from how society would name an organism. For example when we name our pets or children, the selected names are not unique. After all, how likely is it that anybody at this time would come up with an original, unique name. In taxonomy those types of names would be referred to as common names, which have been given to many species of organisms. It is not unusual for several common names to be applied to a single species and often a common name may be applied to several species. Although many well known species of organisms have common names, they are not officially used in science because of the confusion that they may cause. For example, the common name "Spanish Moss" is applied to at least two species of unrelated organisms in North America, Ramalina menziesii (Fig. 1) and Tillandsia usenoides (Fig. 2). The former is a lichen, which represents a symbiotic relationship between a fungus and an alga and the latter is a flowering plant.
Figure 1: Ramalina menziesii (Courtesy of Beatrice Senn-Irlet)
Figure 2: Tilandsia usneoides (Courtesy of David Webb)
Not only is this an example of a common name that applies to two different, unrelated species, but also one, which is misleading since neither species is a moss, nor is it Spanish. Conversely, Plantago major, a widespread weed, in Europe, is sometimes called "broad leafed plantain", but it also has at least 45 other English common names. Because the European countries speak a number of different languages, there are also 11 French names, 75 Dutch names, 106 German names and many more in other languages (Stern, 1997). Many of these common names may also apply to other unrelated plants. Nevertheless, because common names were the first names that many organisms received and are the names that the general population uses, it is unlikely that the less confusing species names will ever replace common names in our daily usage.
The Development of the Bionomial System and Classification Schemes
A History of Taxonomy
Although the usage of binomials seems to be a simple enough concept, its development took well over a thousand years. In summarizing the events that led to the binomial system, we will concern ourselves mainly with events having to do with plants because fungi as well as algae and bacteria were classified as plants until Whitaker (1969).
The first names applied to plants were undoubtedly "local" common names. Because such names may be restricted to small communities, another nearby community would likely have a different common name for the same plant. This seems to be the likely mechanism by which numerous common names may have been applied to a single plant. The earliest known attempt at classifying plants was in the 3rd Century B.C., by Theophrastus who classified approximately 500 species of plants into three categories: trees, shrubs and herbs, and utilized leaf characteristics and other more vague features in distinguishing between different species.
A more applied scheme of classifying plants was devised around the 2nd Century A.D. Dioscorides, a Greek physician, classified plants according to their medicinal usage. He illustrated and described 600 species of plants in his book, De Materia Medica. His books, which were highly respected, were frequently reproduced by hand copying and became known as herbals. Unfortunately, there is such a thing as being too highly esteemed. The herbals became the sole source of medicinal information between 400 and 1400 A.D. It was considered heresy to speak against or to question information in the herbals, which resulted in few new ideas during this period of time. This was the period referred to as the Dark and Middle Ages, in Europe, and for a thousand years the advancement of knowledge in science came to a halt.
It would not be until the 15th Century that a proliferation of knowledge would come about. This was, in part, due to new ideas that came about, but also had to do with the invention of the printing press by Johanne Gutenberg (Fig. 3), which made the mass reproduction of books possible. Prior to this invention, books were hand written. Thus, few books were available. This was also when the herbalists began to classify plant species according to their usage. This differed from the herbals in that the herbalist now classified plants not only for their medicinal usage, but also by their usage as food, clothing, as well as other applications. Included among these plants were also usages of some species of fungi.
Figure 3: Johann Gutenberg, German printer usually credited with the invention of the printing press.
At this time common names were still being used by the layperson, but botanists were now using descriptive phrases or phrase names that both described and named plant species and even credited these names to the authority for each species. Also, by this time the use of Latin had become widespread in schools and universities throughout Europe. Thus, phrase names were written in Latin for ease of communication. The phrase name usually consisted of no more than 12 words. However, as in the case of the common names, there was still more than one phrase name for each species. Different phrase names applied to the same species often differed by only a few adjectives.
In 1700 Tournefort originated the concept of phrase names that began with the genus of the species followed by a short Latin description. For example, the phrase name for the spearmint plant was Mentha floribus spicatis, foliis oblongis serratis. Mentha is the genus name followed by a brief Latin description. In English, this would translate to "mint with flowers in a spike, leaves oblong and toothed". For obvious reasons, a phrase name was not practical for naming organisms. Can you imagine having to repeat the above scientific name each time reference was made to spearmint?
Carolus Linnaeus was credited with originating the binomial species names in his 1753 publication of Species Plantarum and he also "popularized" botany at this time. Less is said of this contribution and how he popularized it. At the time of Linnaeus, it was realized that plants, like animals, reproduced sexually. Using this knowledge, Linnaeus published in 1735, his Systema Naturae, on his sexual classification of plants. His classification scheme included counting the number of male (stamens) and female (pistils) reproductive organs that were present of flowers, which seems innocent enough. However, it was the matter in which Linnaeus represented sexual reproduction in plants that became somewhat controversial. On the sexuality of plants, Linnaeus wrote the following:
"The actual petals of a flower contribute nothing to generation, serving only as the bridal bed which the great Creator has so gloriously prepared, adorned with such precious bed curtains, and perfumed with so many sweet scents in order that the bridegroom and bride may therein celebrate their nuptials with the greater solemnity."
His metaphors concerning reproduction in plants, using human analogies shocked proved to be too explicit for the moral values of his time. An excellent example of how Linnaeus used the characteristics of the flower to distinguish between the different classes can be found at http://courses.eeb.utoronto.ca/eeb337/B_How/307b1Linn.html:
A, Monandria - One husband in marriage; B, Diandria - Two husbands in the same marriage; C, Triandria - Three husbands in the same marriage; D, Tetrandria - Four husbands in the same marriage
E, Pentandria - Five husbands in the same marriage; F, Hexandria - Six husbands in the same marriage; G, Heptandria - Seven husbands in the same marriage; H, Octandria - Eight husbands in the same marriage
I, Enneandria - Nine husbands in the same marriage; K, Decandria - Ten husbands in the same marriage; L, Dodecandria - Twelve to nineteen husbands in the same marriage; M, Icosandria - Generally twenty husbands, often more
N, Polyandria - Twenty males or more in the same marriage
O, Didynamia - Four husbands, two taller than the other two; P, Tetradynamia - Six husbands, of which four are taller
Q, Monadelphia - Husbands, like brothers, arise from one base; R, Diadelphia - Husbands arise from two bases, as if from two mothers; S, Polyadelphia - Husbands arise from more than two mothers; T, Syngenesia - Husbands joined together at the top; U, Gynandria - Husbands and wives growing together
V, Monoecia - Husbands live with their wives in the same house, but have different beds; X, Dioecia - Husbands and wives have different houses; Y, Polygamia - Husbands live with wives and concubines
Z, Cryptogamia - Nuptials are celebrated privately
While this sexual system of classification proved to be easy to learn and made it possible for the non-botanist to identify plants, it also invited much criticism, some from his contemporaries. They included such comments as:
“Loathsome harlotry as several males with one female would not be permitted in the vegetable kingdom by the Creator!"
"a man would not naturally expect to meet with disgusting strokes of obscenity in a system of botany"
Encyclopedia Britanica, 1771
"A literal translation of the first principles of Linnaean botany is enough to shock female modesty. It is possible that many virtuous students might not be able to make out the similitude of Clitoria"
Bishop of Carlisle
Siegesbeck was his biggest critics and made many other such comments. However, Linnaeus may have gotten the last laugh when he named an ugly, smelly, little weed Siegesbeckia orientalis, after Siegesbeck. While controversial, Linnaeus' the controversy of his sexual system is largely forgotten and he is best remembered for his reintroduction of the the binomial system first originated by Gasbar Bauhin.
Linnaeus' Species Plantarum, two-volume publication was an ambitious effort to name and classify all of the known plants during Linnaeus' time. As with most taxonomist of his time, he actually used phrase names in recording the different species of plants that he recognized. However, Linnaeus added a shorthand notation for each species. In the left margin of each phrase name, he wrote a word, which, when combined with the genus, formed a convenient abbreviation for the phrase name. For example, "spicatis" was added to the margin of the phrase name for spearmint and "piperata" was added to peppermint (Fig. 4). The abbreviation for these species could then be referred to as Mentha spicatis and Mentha piperata, respectively. Other workers soon followed Linnaeus in recording species names in this fashion and eventually phrase names were replaced by binomials.
spicata. 2. MENTHA floribus spicatis, foliis oblongis serratis.
Hort. ups. 168.
Mentha sylvestris, longioribus nigrioribus & minus in-
canis foliis. Baub. Pin. 227.
piperata. 4. MENTHA floribus capitatis, foliis lanceolatis serratis subpetiolatis.
Mentha spicis brevioribus & habitoribus, foliis menthae
suscae, sapore servido piperis. Raj. angl. 3. p. 234
t. 10. f. 2.
Habitat in Anglia.
Figure 4: Two species of Mentha from Species Plantarum with phrase names, and specific epithet at the left margin.
Although Linnaeus (Fig. 5) has been credited with inventing the usage of binomials for species names, this idea did not originate with him. It began with Gaspard Bauhin (Fig. 6), a Swiss botanist who used binomials to record plant names in 1623, in his Pinax Theatri Botanici. However, the idea of the binomial species name did not catch on at that time. Thus, Linnaeus actually reintroduced usage of binomials for species names and popularized it. However, he did credit Bauhin with originating this system.
Figure 5: Carolus Linnaeus (from the Wikipedia, the Free Encyclopedia web page)
Figure 6: Gaspard Bauhin (Perry-Castañeda Library, University of Texas at Austin)
Today, all species names are binomials, and if cited formally, the name of the author who described the species or an abbreviation of the author's name is placed after the binomial, e.g. Mentha spicatis L. The "L." in this case credits Linnaeus as the person who first described this species. There are also variations as to how a person is credited after a species name. For example, in the supermarket mushroom, Agaricus bisporus (Lange) Imbach, Lange, whose name is in parentheses, was the original person who described the species. The parentheses indicate that the species was originally described in another genus. In this case the genus was Psalliota. Imbach, whose name appears after Lange, is credited with making the change from Psalliota to Agaricus. Therefore, if we wanted to find all of the literature that is available on this species, we would have to look under both Psalliota bisporus Lange and Agaricus bisporus (Lange) Imbach. The idea of citing an author's name to credit that person with the discovery of the species and/or the person changing the name of the species also did not originate with Linnaeus. Botanist had long attributed authors' names to species so that a history of changes that occurred in the species names could be followed. Also, it was a matter of giving credit, as well as the blame, for the changes that were made to a species name. There are various reasons for changing the name of a species and such notations allow us to trace these changes. Commonly, a name has to be changed because two species have the same name. Because of this and numerous other problems that can arise, there must be rules that govern the procedures for the naming of species as well as provisions for problems that may arise.
In discussing binomials, some mention has already been made concerning certain practices in the naming of species and their citations, i.e. the name is in Latin, it is underlined or italicized with the author of the species following the epithet. Although it is not obvious, a little thought on the subject should tell us that unless there is agreement, among taxonomists, concerning the method by which plants are named and classified, we can still expect confusion to reign. However, it would be over a hundred years before such an agreement was made. In 1867, 150 botanists, mostly from Europe and America, met in the First International Botanical Congress, to standardize the rules and regulations that would be used when plants are named. The rules adopted by these botanists are known as the International Code of Botanical Nomenclature (ICBN) and has been adopted by botanists throughout the world. The ICBN not only describes how species are named, but also when names must be changed, what names are unacceptable, how to validly publish a new species that you have just discovered and many other topics having to do with taxonomy of plants. The ICBN also governs the taxonomy of algae, cyanobacteria [other bacteria are governed by the International Code of Nomenclature of Bacteria (ICNB)] and fungi. Zoologist later adopted The International Code of Zoological Nomenclature that governs the naming of animals.
One of the important rules that was agreed upon after many years of debates was that the "starting date" of plant names should begin with 1753. The reason for this selection was that this was the year that Species Plantarum, which included the binomial names of just about all of the known plants at that time, was published. Species names published earlier than 1753 and not recorded in Species Plantarum were not recognized as valid names. However, Linnaeus included very few species names of fungi and a different starting point for species names of fungi was originally used. There were originally two starting points for fungi: Christiaan H. Persoon's Synopsis Methodica Fungorum issued in 1801 and Elias Magnus Fries' Systema Fungorum, first volume (of three) issued in 1821. Persoon was the starting point for rust and smut fungi and Fries was the starting point for the remaining fungi, especially fleshy fungi, i.e. those with fruiting bodies. In the 1987 Botanical Congress, this all changed. It was decided that the starting date for valid species names of fungi would be moved to 1753. However, species recognized in Synopsis Methodica Fungorum and Systema Fungorum were sanctioned, which means that even if there was an earlier name for a species published in these tomes, they would still have priority in spite of the fact that there was an earlier species name.
The Use of Latin
When a new species of organism has been discovered, it must be given a Latin name and be published with a Latin description in order for the species name to be valid. Why Latin? Originally, Latin was used because it was the language of scholars, which made communications possible between individuals whose native language may differ. However, presently, few people in the sciences can speak or write Latin. So, why do we continue to use Latin? The main reason is because it is an unchanging language. This is important since contemporary languages are "dynamic". That is, they are constantly undergoing changes. Words often take on new connotations with time.
The Development of Categories of Organisms (Kingdom, Phylum, Class, Order, Family and Genus)
Although the contribution of Species Plantarum by Linnaeus was important to biology, its usefulness would have been limited if there was not a means by which unknown plants could be identified without the aide of a teacher. Thus, in addition to cataloging the species name, Linnaeus divided the genera of plants into 24 "classes", based on the number of floral stamens. Plants that lacked flowers and seeds, such as mosses, ferns and even fungi, were classified in their own class. By placing plants in categories, in this fashion, Linnaeus provided, for the first time, a means of identifying unknown plants.
The two earlier classification schemes that were discussed earlier were based on medicinal usage of plants and general usage of plants, in herbals and herbalists, respectively. In these schemes, the identity of a plant could not be identified without the aide of a teacher. After all, how would you determine the usage of a plant if you do not know its identify? Theophrastus' classification of plants into trees, shrubs and herbs with the added use of leaf characteristics was a more sensible means of classifying plants and is more comparable to the features that we use, today, to identify and classify plants.
Although the classification scheme of Linnaeus enabled students of botany to identify plants, it did not classify related plants in the same groups. Ferns, mosses and fungi, for example, were placed in the same class even though they are obviously not related to one another, and cone bearing, e.g. pines and firs, and flowering plants were classified together, as well. This type of classification scheme is not desirable and even Linnaeus admitted that this scheme was composed for convenience rather than for the grouping together of related plants such as in a natural system of classification. Although the need for such a system was known even before Linnaeus, its universal usage in science has only come about recently.
There are many classification schemes, each one can be argued to be more natural, in one respect, than another. It seems that as long as people will continue to make up such systems, there will always be disagreements. One point, which has been agreed upon, is the categories in which plants are classified. Presently, closely related species are arranged into a genus, genera are arranged into families, families into orders, orders into classes, classes into phyla and phyla into kingdoms. Using this classification hierarchy, we can place any fungal species into the different categories or taxa in various classification schemes. For example, the complete classification of Agaricus bisporus, the super market mushroom, in three different systems of classification has been reproduced below:
|Classification Categories of Fungi||Moore-Landecker (1993)||Alexopoulos, Mims & Blackwell (1996)||Hawksworth, Sutton & Ainsworth (1983)|
*Each category in the classification scheme may have a subcategories such as "subdivision" or not, as can be seen in Moore-Landecker's and Alexopoulous, Mims & Blackwell's classifications where it is absent.
Even with the progress that have occurred in molecular biology, there is still disagreement even at the broadest categories of our classification schemes. Intuitively, kingdoms would appear to straightforward, but this is not the case. As more is learned from molecular studies of various organisms, this has only caused more disagreement as to the classification scheme to use at the kingdom level.
The Concepts of Kingdoms
The kingdom is our broadest category and in the earliest classification, only two were recognized, Plants and Animals. Plants were then characterized as organisms that lack motility, and do not consume food while animals have the ability to move and eat their food. Even today, the lay public still categorize life in the two kingdoms, and for most organisms that we are in daily contact with this is a workable system. We know that pines, ferns and mosses are different types of plants and that dogs, birds and fishes are different categories of animals. However, most microscopic organisms do not fit comfortably into either kingdoms. Fungi, for example, were placed into the Plant Kingdom because they lacked motility and their cells were surrounded by a rigid cell wall, but unlike plants they cannot photosynthesize. The genus Euglena (Fig. 7) is one of many examples that have been classified as both a plant and an animal. It is a unicellular organism found in fresh water and can swim through the water with a "hair-like tail" called a flagellum (plural: flagella). A groove or a gullet is present in the cell that allows it to ingest food. However, Euglena also has chloroplasts and, like plants, can make its own food through photosynthesis. Because Euglena possess both plant and animal characteristics, it was classified as both a plant and an animal. Despite these problems, this two kingdom system was used until Whitaker (1969) proposed that organisms be classified into five kingdoms: Monera (=Bacteria), Protista (=Mostly Algae and Protozoans), Plantae (=Plants), Mycetae (=Fungi) and Animalia (=Animals). Until recently, Whitaker's five kingdoms was the system of classification of organisms used in textbooks since the early 1970's.
|Fig. 7: Euglena is neither plant nor animal.|
Although Whitaker was credited with this system of classification, most of the additional kingdoms that he recognized did not originate with him. It had long been accepted, in biology, that many organisms did not fit comfortably into a two kingdom system. A third kingdom, Protoctista, was first proposed by the German biologists J. Hogg and Ernst Haeckel, in 1860. This kingdom included organisms such as fungi, bacteria, algae and protozoans that were characterized by having simple cellular organization and not producing complex tissues, and also often had a combination of plant and animal characteristics. However, it was obvious that these organisms were not closely related and did not form a natural grouping. A modification of this system was proposed by Herbert Copeland, in 1938. He removed bacteria from Protoctista and erected a fourth kingdom that he called Monera. From here, the modification from Copeland's classification was not a big leap to Whitaker's, which differed only in the removal of the fungi from Protoctista and placing them in their own kingdom (=Mycetae). It should also be noted that while a five kingdom system of classifying organisms has been used in most text books, for more than 25 years, the concepts of Protoctista, now Protista in most textbooks, and Mycetae have changed during this period of time. With these changes in concepts, other classification schemes have been proposed. Some schemes have expanded the number of kingdoms to six, and eight and one has even reduced the number to three. Thus, there is still not agreement among scientist as to the number of kingdoms that should be recognized in the classification of organisms, and it is probable that there never will be.
The lack of agreement on a single classification scheme does not mean that one system is necessarily better than another. Only that they are different. One point to keep in mind concerning the various classification schemes is that they are man-made and are only our concepts of how organisms should be classified. The organisms, themselves, have not been changed one iota as a result of these changes in classification, even though this is the impression that we are occasionally left with. One example that might amuse you is the change in policy of the Hawaii State Plant Quarantine Department, with respect to a group of organisms commonly referred to as "blue-green algae". Plant quarantine's import policy of this group of "algae" was to treat them as algae. However, after they had learned that blue-green algae were reclassified, and placed in the Kingdom Monera, which met that they were now interpreted as being closely related to bacteria rather than algae. All of a sudden, the import policy regarding blue-green algae also changed and are now treated as bacteria. Blue-green algae have probably undergone relatively few changes in over a billion years, but yet the change in policy by the State of Hawaii would seem to indicate that there was a drastic change in these organisms simply because they have been reclassified into a different kingdom.
Review of Kingdom and How to Construct a Dichotomous Key
There are commonly five phyla that are recognized in the Kingdom: Fungi:
Chytridiomycota: Flagellated zoospores and gametes
Zygomycota: Zygospore supported by suspensors on either side.
Ascomycota: Ascospores borne with asci.
Basidiomycota: Basidiospores borne on sterigmata of basidia
Deuteromycota: Sexual stage absent, reproduction by conidia borne on conidiophores.
Dichotomous keys are a means of identifying organisms without the aid of a teacher. This was one of the contribution for which Linnaeus was recognized. When constructing such a key, two choices are offered and the student selects one of the choices based on which choice seems to best fit the organism being identified. Let construct such a key for the five phyla of Fungi above:
Flagellated stages present, mostly aquatic, thallus unicellular to mycelial. If mycelial,
AA. Flagellated stages absent, usually not aquatic, Thallus mycelial or yeast or both................................................................................................B
B. Mycelium usually coenocytic, Sexual spore, zygospore, asexual spores borne in sporangia….…….........................……Zygomycota
BB. Thallus mycelial, if present, septate, or yeast, or dimorphic. Sexual spore if present, not zygospore, asexual spore,
C. Sexual spores ascospores, borne in asci, either on or in fruiting body or naked. Asexual spores, when present,
CC. As above, but sexual spores not ascospores borne in asci.............................................................................................................................D
D. Sexual spores basidiospores, born on basidia...............................................................................................................Basidiomycota
DD. Sexual stage mostly absent, reproduction asexual by conidia...........................................................................Deuteromycota
Usually, after you arrive at a name, the description of the organisms is described after the key. Just as there are different groups of plants, ex., ferns, mosses, conifers, flowering plants, etc., there are different groups of fungi.
Chytridiomycota description and images (Figs. 8-10), the terrestrial Fungi (Figs. 11-16) are classified according to the types of sexual spores that are produced. The Chytridiomycota can readily be distinguished from the terrestrial fungi being the only Fungi that have swimming zoospores and gametes. These stages are propelled by a single hair-like appendages referred to as a flagellum.
|Figure 8: Zoospore of Chytridiomycota (left) and Allomyces gametangia||Figure 9: Male and female gametes released from Allomyces gametangia||Figure 10: Zoospores of Allomyces released from Zoosporangium|
Zygomycota and Ascomycota descriptions and images: The remaining fungi are mostly terrestrial without flagellated stages. The Zygomycota can be defined by its thick walled zygospore (Fig. 11), produced ruing sexual reproduction and its asexual spores borne in sporangia. The Ascomycota is defined by asci and ascospores (Fig. 12) produced during sexual reproduction that may be formed on a complex fruiting body Fig. 13)
|Figure 11: Zygospores are sexual spores characteristic of the division Zygomycota. Spores have thick, black cell walls and are supported by two cells called suspensors.||Figure 12: Ascospores are sexual spores borne in cylindrical cells called asci (sing.=ascus) belong in the division Ascomycota. Asci and ascospores are usually produced in fruiting bodies. There are typically eight ascospores/ascus.||Figure 13: An example of a disk-shaped Fruiting body in the Ascomycota. Asci and ascospores form a continuous layer on the red hymenial surface.|
Basidiomycota description and images: This phylum is defined by the basidia and basidiospores (Fig. 14-15) during sexual reproduction. These structures may be borne on fruiting bodies such as the gills of mushrooms (Fig. 16).
|Figure 14: A low magnification of a piece of lamella from a mushroom fruiting body. Elliptical objects are basidiospores.||Figure 15: A close-up of two basidiospores borne on a basidium. Basidiospores borne on basidia are characteristic of the division Basidiomycota, which includes mushrooms.||Figure 16: Cortinarius clelandii mushroom. basidiospores and basidia are borne on the lamella of mushrooms.|
Deuteromycota description and images: This phylum is defined by its lack of sexual reproduction, but this is not strictly true. Some species have been induced to reproduce sexually and can be reclassified as usual a member of the Ascomycota and less commonly the Basidiomycota. Reproduction is mostly by conidia. Some examples can be seen in Figs. 17-19This phylum is said to be a "form taxon" because the fungi classified in this phylum are not known to reproduce sexually. There are species in which the sexual stage has been induced in the laboratory and found in nature. When this occurs, they sexual stage is usually referable to the Ascomycota or less frequently to the Basidiomycota.
|Figure 17: Trichocladium conidia||Figure 18: Periconia conidia||Figure 19: Pencillium conidia|
There are also two additional phyla I would like to mention that were once thought to be "Fungi", but are longer in this have been classified as such. The phylum Oomycota (Figs. 20-22) has all of the appearances of a fungus and most of combination of characteristics, but does not have a chitinous cell wall. It is characterized by the large oogonia that contain eggs (Fig. 22), which is named for the phylum, literally "egg fungus". Note that the male tube containing the sperm nuclei is also attached. There are other characteristics, but this would be beyond the scope of this course. Asexual reproduction also commonly occurs by zoospores (Fig. 20) borne in zoosporangium (Fig. 21)The Oomycota causes some of the more serious plant diseases and has had a tremendous, historically, on several occasions that we will cover.
|Figure 20: Two types of zoospores released during reproduction.||Figure 21: Zoosporangium of Oomycota. Note dark color at tip. The tip is full of zoospores.||Figure 22: Oogonium and antheridium of Oomycota.|
The phylum Myxomycota is commonly called the the slime molds because of its plasmodial stage (Fig. 22). It is no longer classified as belonging to the fungi because they lack mycelium, cell walls in its vegetative stage and do not absorb their food. You may recall from the BBC video that slime molds are called the "mold that walks" because they have amoeba and plasmodial stages that are mobile as they search for food. Probably the only reason that they were classified as fungi is because they reproduce with spores.
|Figure 22: The plasmodium is the stage that eats as it creeps along.||Figure 23: Stemonitis, The plasmodium becomes reproductive and gives rise to sporangia||Figure 24: Lycogala is another genus with much larger sporangia.|
Are Classification Schemes and The Rules That Govern the Naming of Plants and Fungi Really Necessary? The Curtis Gates Lloyd Story.
You can see then that there is some disagreement as to the proper classification of Organisms into kingdoms, and revisions are constantly being made as to the regulations in the naming of plants species as well as other categories. Furthermore, there are few botanists that know, in detail, or even understand what is in the ICBN. Most botanists agree that we cannot do without these rules and regulations, but there are also many who wonder why species names must change just because it conflicts with the ICBN and question the need for such a document, or even the existence of taxonomy as a discipline within biology. One of the most well known critic of the ICBN was Curtis Gates Lloyd (Fig. 24). The story of his opinion on this subject and what he did about it makes for another amusing story.
|Fig. 24: Curtis Gates Lloyd|
Lloyd was one of the most famous, or infamous mycologists depending on how you feel about this person. Curtis Lloyd was actually not a mycologist by profession. In his first career, he and his two brothers ran a successful wholesale pharmaceutical company called Lloyd Brothers. The company was so successful that by 1917 Lloyd retired while still relatively young and hired a replacement to take charge of his department so that he could pursue his mycological interest. His interest in mycology came about through his interactions with Andrew Price Morgan, a well known mycologist, of the late 19th and early part of the 20th. Century. It was from Morgan that he learned about and developed his interest in Gasteromycetes, e.g. puffballs.
Although Lloyd eventually became an excellent taxonomist of fungi, he disagreed strongly about the placement of authors' names after the species that they had described or had changed. He felt that this was the main cause for proliferation of species names as well as the large number of name changes and hasty publications. Lloyd believed that this was a means by which "name jugglers" sought to immortalize their own names. Because of his belief, he refused to follow journals' requirement of placing the authors, of species, after binomials, which resulted in the rejection of his manuscripts for publication. However, his manuscripts were published in Mycological Notes, a journal he started, and published between 1898-1925. Although, this journal only published seven volumes and was discontinued after his death, it was a well respected journal with many important publications, and can be found in most university libraries. In addition to his studies on fungi, it was not uncommon for Lloyd to lampoon the practice of "name juggling" in Mycological Notes. Nevertheless, after a number of years, he found that he had not only described a large number of new species, but also had to "juggle" a number of species names as well. One of his notorious acts was his creation of the fictitious Professor N.J. McGinty of Pumkinville Polymorphic Institute, whose name was cited as the authors of species that he described, which included the fictitious Lycoperdon anthropomorphous, as well as for name changes that he had made. Although he would never admit it, the creation of McGinty may have been his way of saying that he understood the necessity for name juggling. However, his criticism of name juggling would continue for the rest of his life. In what was possibly his last "poke" at the mycological establishment, four years before his death, Lloyd prepared his own tombstone, with the following epitaph:
Curtis Gates Lloyd
Monument erected in 1922 by
himself, for himself during his
life to gratify his own vanity.
What fools these mortals be.
This was a monument erected to himself in the cemetery at Crittenden, Kentucky, which he said "was intended as a burlesque on tombstones in general and a satire on mycologists who have passed".
Many of Lloyd's collections were obtained through requests by mail and in returned he offered his journal free to the senders of collections. His contributions to mycology were many. During his lifetime, he accumulated a rather large herbarium of fungi which is still maintained today as is his library, which has many rare mycological books. His herbarium was composed only of large fungi because he did not like to use a microscope and believed in distinguishing species with only what was visible to the naked eye. He was the stereotypic scientist. He was never married, except to his work. He didn't have a house. He maintained bachelors quarters in his museum.
Binomial: A species name composed of two parts, the genus and specific epithet.
Class: A taxon composed of closely related orders.
Common name: Name given to a species by local community. Name given to species not governed by rules and may composed of any number of words and may be of any language.
Dioscorides: Greek physician in 2nd Century A.D., author of De Materica Medica, which categorized plants according to their medicinal use. This book was copied and recopied for 1000 years.
Phylum: A category in the plant hierarchy.
Flagellum (plural = flagella): Hair-like structure that functions in mobility of microscopic organisms.
Herb: A non-woody plant whose stem generally dies back at the end of each growing season.
Herbalist: One who classifies plants according to their uses.
Herbal: A book on plants and their medicinal usages.
International Rules of Botanical Nomenclature: Rules governing the naming of plants, algae and fungi.
Kingdom: The broadest taxonomic classification into which organisms are grouped, based on fundamental similarities and common ancestry.
Linnaeus: Botanist who popularized botany, developed a system of classification in plants that permitted the identification of plants without a teacher, credited for the use of binomials in species name and for recording all of the known species of known plants in his Species Plantarum, published in 1753.
Monera: The kingdom to which bacteria belong.
Mycetae: The kingdom to which fungi belong.
Natural System: Referring to a system of classification in which closely related organisms are grouped together in the same taxon.
Phrase name: First type of scientific name composed of the genus followed by a brief Latin description.
Plantae: The kingdom to which plants belong.
Protista: The kingdom to which algae, protozoan and other simple organisms, which do not have complex tissues belong. Originally referred to as Protoctista.
Shrub: A short, woody plant or bush, having several stems arising from the base and lacking a single trunk.
Stamen: The male part of a flower that contains the pollen of the flower.
Taxon (plural = taxa): A general reference to a taxonomic category or group, e.g. kingdom, division, class, order, family, genus or species.
Taxonomy: That part of biology that studies the naming and classification of organisms.
Theophrastus: Greek philosopher credited with the first classification scheme of plants.
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