 Have you left a piece of bread outside and forgotten to throw it off and noticed greenish or bluish spots forming on it? Have you noticed how a bread raises after adding yeast and allowing it to rest for a couple of hours? What about mushroom Manchurian? Have you eaten mushroom Manchurian? Well, all these are examples of fungi. Now fungi as we know are eukaryotic, non-photosynthetic sap profiles. This means that they depend on dead or decaying organic matter for food. As with any organism, fungi are easy to study once they have been classified into different taxa. They have their own kingdom, kingdom of fungi, under which there are many phyla. To classify fungi, biologists use a few major characters. Let's recall those characters of fungi. First off, fungi are made up of long tube-like filamentous structures called hyphae. Now these hyphae interlink together and form a network called mycelium. Now there are two types of hyphae. One is senocytic, which means that the hyphae is continuous. You see here the hyphae is continuous. There is no break in between and the other is septate in which the hyphae are interspersed with cross walls. These lines that you see here are cross walls. Senocytic hyphae are multi-nucleate. They have many nuclei. Septate hyphae, for each part, there's only one nucleus. Fungi are capable of reproducing vegetatively, asexually and sexually. Asexual and sexual reproduction occurs to the formation of spores, which then germinate to produce new fungi. Now these spores are formed inside structures called fruiting bodies. So the structure of the hyphae, the mode of reproduction and the type and structure of the fruiting body produced form the basis of fungal classification. Based on these characters, fungi are classified into four major phyla, phycomycetes, ascomycetes, besediumycetes and dutromycetes. Let's first start with phycomycetes. Examples of phycomycetes include mucor, albugo and rhizopus, which is the infamous bread mold. Phycomycetes have a senocytic mycelium, which means their mycelium is continuous and they are majorly found in aquatic environments. Some are even found in decaying wood like moist places and soil and some are obligate plant parasites. Albugo is extensively a plant parasite. Phycomycetes are capable of reproducing asexually and sexually. Asexual reproduction in phycomycetes occurs through zoo spores or aplanospores. Zoo spores are motile. They have a phlegelum, which helps the spores move. Aplanospores are non-motile. Now these spores, asexual spores, are produced inside structures called sporangium. They are produced endogeniously, which means inside this structure called sporangium. So these dots you can see here, these are the spores. The zoo spores are the aplanospores. Sexual reproduction occurs through zygospores and zygospores look something like this. Now, how are these zygospores formed? Well, when two compatible haploid hyphae come together, they cytoplasm first fuses and then eventually the nuclei fuse to form the diploid zygospore. And the diploid zygospore then undergoes meiosis to produce haploid spores. The next phylum is Ascomycetes or sac fungi. I'll explain in just a minute why they're called sac fungi. Ascomycetes have a lot of economically important fungi. For example, penicillium, from which we get the antibiotic penicillin. Moral, which is considered a delicacy in many parts of the world. And yeast, which is baker's yeast, which is extensively used in baking and brewing industries. They're all examples of Ascomycetes. Ascomycetes have a septate mycelium, which means that their mycelium is interspersed with crosswords. Ascomycetes are mainly decomposers, but some are parasites. For example, candida, which infects humans, is an Ascomycete parasite. Ascomycetes can reproduce asexually through the formation of conidia. Now, conidia looks something like this. Like this white bead-like structures that you see here, these are the conidia, the asexual spores. These conidia are produced exogenously on structures called conidia force. So, conidia force are nothing but modified mycelium, special mycelium. So, on the tip of the mycelium, the conidia are formed. Sexual reproduction in Ascomycetes occurs through the formation of Ascospores. Ascomycetes, Ascospores. Ascospores are arranged in structures called ascii. The plural form is ascii and the singular form is ascus. Now, the ascii look something like this. They are sac-like structures within which the ascospores are arranged. Because of this, Ascomycetes are also called sac fungi. These ascii are sac-like structures. Now, altogether, Ascospores and ascii are arranged inside this bigger structure called Asco-carp. So, this entire thing is the Asco-carp. These gray lines here, they are the ascii. Inside those ascii are the Ascospores. So, Asco-carps are the fruiting bodies for Ascomycetes. The fruiting bodies from which the spores are spread around and germinate. The next phylum is Bacidium Icetes. Examples of Bacidium Icetes include agaricus, which are mushrooms and puffballs and smut. Bacidium Icetes also have a septate mycelium like Ascomycetes. And they are the plant parasites, smut and raster examples of plant parasites. Some also grow in moist places like soil and decaying wood. Bacidium Icetes can reproduce asexually but not through the formation of spores. This is what makes Bacidium Icetes unique. Asexual reproduction in Bacidium Icetes is through fragmentation. Now, what is fragmentation? Basically, it's just one hyphae splitting into many pieces. And each of these hyphae then form a new fungal network. Sexual reproduction is through Bacidium spores. Bacidium Icetes, Bacidio spores. Bacidio spores are formed exogenously on structures called Bacidia. Let's take a look at this image to understand Bacidio spores better. So, this entire structure here, this is called the Bacidio cap within which you have these finger-like projections which are the Bacidia or the singular is Bacidium and exogenously on the Bacidium for haploid Bacidio spores are formed. So, this bigger structure is the Bacidio cap. These finger-like structures within the Bacidio cap are the Bacidia and outside the Bacidia exogenously these Bacidio spores are formed. So, this entire structure of Bacidio cap is the fruiting body for Bacidium Icetes. Like Asco carps are the fruiting body for Asco mycetes, these Bacidio carps are the fruiting body for Bacidium mycetes. The last fungal phylum is Dytromycetes which are also called Imperfect fungi. Why are they called Imperfect fungi? We'll get to that in just a minute. Some examples of Dytromycetes include Altenaria and Celomycetes. Dytromycetes have a septate mycelium. Dytromycetes are found growing in litter and some are even parasites. Now, Dytromycetes is generally for fungi that don't fit the mold. This is because they reproduce only through asexual or vegetative means. There is no sexual reproductive structure formed. Vegetatively, Dytromycetes reproduce through fragmentation and budding. Asexualy, they reproduce through conidious pores. Now, these Dytromycetes are a bit of a grey area in fungal classification. You see, there were a few species of fungi whose sexual structure was quite different morphologically from its asexual structure. So, those sexual structures were classified under some other phylum like Ascomycetes maybe. But their asexual structure was classified here under Dytromycetes, thinking that these fungi didn't have sexual structures at all. But later, research and evidence indicated that the sexual structure and the asexual structure belong to the same species. So, whatever was classified here, whatever asexual structure that was classified here, was then moved along with the sexual structure to a higher phylum. So, this grey area is important in highlighting that classification is not a rigid structure. There is always room for improvement. When scientists discover new evidence, they may have to reevaluate the taxon and witchin organism as classified. Keep in mind that the evidence need to be solid. It has to be concrete evidence and scientists just can't move organisms willy-nilly. In fact, many of the older phyla that were used to classify fungi have now become obsolete and have been replaced with newer phyla.