The Wonderful World of Fungi
Organisms That Can Really Grow on You
By: H. Wayne Shew, Ph.D.
NAB Certified Pollen Counter
Fungi (singular fungus) are microscopic to macroscopic organisms that are ubiquitous in nature. They are found in every imaginable habitat and have remarkable nutritional abilities. The word “fungus” is normally pronounced with a hard “g”, as in the rhyme, there must be a fungus among us, while the plural word fungi, is normally pronounced with a soft “g”, that is, “fun ji.” Occasionally you will hear the word fungi pronounced with a hard “g” sound, hence, I consider myself to be a real “fun guy” since I enjoy all things mycological (all things fungal). I think fungi are incredible organisms, and their great diversity and unique life histories make them a lot of fun to study.
Fungi are truly remarkable organisms. They are unique in many ways and differ considerably from the plants and animals that we are most familiar with. The fungi are so different from other organisms that they are placed in their own taxonomic kingdom, Kingdom Fungi. The fungi were initially considered to be plant-like organisms that lacked chlorophyll, and were traditionally studied by botanists. In the mid-twentieth century, the fungi were moved taxonomically to their own kingdom, Kingdom Fungi. There were four other kingdoms under Whitaker’s taxonomic system that was first proposed in the 1960’s; these included Plantae, Animalia, Monera, and Protista.
Taxonomic systems continue to change as do the organisms that are placed into the various taxa. By the start of the twenty-first century organisms were being grouped into three domains or superkingdoms. The domain called Eukarya contains those organisms classified as fungi as well as those organisms that were traditionally classified as fungi but are now placed in different kingdoms. See outline which follows:
- Three Domains or Superkingdoms
- Archaea – prokaryotic
- Eubacteria – prokaryotic
- Eukarya – eukaryotic
- Eukarya is divided into a number of kingdoms. How many kingdoms are placed in this superkingdom? It keeps changing so who knows anymore? The following are some kingdoms of organisms in the Eukarya:
- Parabasala – lack mitochondria
- Alveolata – dinoflagellates, ciliates, apicomplexans (Plasmodium)
- Amoebozoa – some protozoans; cellular and plasmodial slime molds
- Chlorophyta – green algae
- Rhodophyta – red algae
- Stramenopila (Kingdom in which water molds, diatoms, golden and brown algae are placed)
The organisms which we traditionally called fungi have changed with reference to where some of them are now placed taxonomically, as has the taxonomy of those that remained within the Kingdom Fungi. For example, the cellular slime molds and plasmodial slime molds (myxomycetes), were once considered fungi but are now grouped with the protozoans. The water molds were at one time placed in the taxon Phycomycetes (word meaning alga-like fungi), but are now grouped with some of the algae in the Kingdom Stramenopila. The organisms that have continued to remain in the taxa considered to be “true fungi” include the Ascomycota, the Basidiomycota, the Zygomycota, and the water fungi called Chytridiomycota. (There is one other group in the Kingdom Fungi, the Glomerulamycota that form arbuscules in the cortical cells of angiosperm plant roots; that is, they form mycorrhizal relationships with plants.) The fungi that produce spores that can get into the aerospora and hence potentially trigger asthma or allergic rhinitis are the ascomycetes, basidiomycetes, zygomycetes, and deuteromycetes. The last group, deuteromycetes, are fungi that are placed in an artificial taxon the Deuteromycota or Fungi Imperfecti because these are fungi which are not known to produce any sexual spores. It is assumed that the fungi in this taxon will ultimately be placed in either the Division Ascomycota or the Division Basidiomycota.
Subsequent blogs will explore the individual groups of fungi listed above and other interesting facts about the fungi. Stay tuned!