- Fungi - Plant-like organisms with no chlorophyll, with a definite nuclei and usually rigid cell walls.
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- Hyphae - Long chains of cells that are aggregated into mats termed "mycelium."
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- Fungi reproduce by spores, which may be sexually (nuclear fusion, meiosis) formed or asexually (mitotically) formed.
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- Fungal classes according to their method of sexual reproduction:
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- Oomycetes produce motile, thick-walled sexual spores, one for each nuclear fusion (eg, the downy mildews). Some oomycetes produce unispore sacs called "sporangia" that become airborne.
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- Zygomycetes produce a single, large thick-walled sexual spore with each nuclear fusion. Zygomycetes also produce asexual spores in sporangia sacs (eg, Rhizopus, Mucor).
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- Ascomycetes produce eight sexual spores in a sac called an ascus and asexual spores called conidia (eg, Leptosphaeria, Chaetomium, Venturia).
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- Basidomycetes form sexual spores externally on pegs produced on structures called basidia.
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- Heterobasidiomycetes produce separate septate basidia (eg, rusts and smuts).
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- Holobasidiomycetes produce single-celled, club-shaped basidia (eg, mushrooms and puffballs).
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- Deuteromycetes are fungi for which a sexual stage has not been identified (Aspergillus, Stemphylium, Alternaria, Cladosporium).
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- Myxomycetes are organisms with both plant and animal characteristics (eg, slime molds). The vegetative stage is an amoeba or multinucleate plasmodium that moves and ingests foods.
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- Actinomycetes are filamentous bacteria that produce dry airborne spores.
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