(mushrooms, sac fungi, yeast, molds, rusts, smuts etc.)

Note: this page is under initial construction.

Sources: University of Arizona Tree of Life Web Project: Fungi; and other sources listed below.

Paleontologically speaking, Fungi appear to have been present prior to the beginning of the Paleozoic Era (540MYa), and while they are an independent group equal to Plants and Animals, genetically they are closer to animals than to plants. They share with animals the ability to export enzymes that break down living cells, which they absorb as food. But they lack stomachs, merely growing into new food supplies as others are depleted, sending out filaments ("hyphae") to exploit new food and sending out spores when local food is depleted. While both filaments and spores are microscopic in size, a fungus colony may become very large (one puffball -- a reproductive structure of a larger body -- has been measured at nearly 9 feet in circumference, and some underground bodies of fungus reach many acres in size).

Fungi are major decomposers of both living and dead organisms (especially of cellulose). Fungi are our most prominant plant pathogens (rusts, smuts, blights, etc., causing some 70% of major crop diseases), and some are parasites of animals (for example, our own southwestern Valley Fever, Coccidiodomycosis). Some form symbiotic relationships with plants (as in lichens) and with animals (especially arthropods), as well as with microbes.

Although we tend to think of fungus in association with warm and wet places, fungi are found in environments that are either cold or dry or both, provided organic matter is present for them to grow in. While they are more numerous and diverse in the wet tropics, they are plentiful in our area. In fact, every plant species examined by scientists up to the present harbors what are called "endophytic fungi" -- fungi that grow intermingled with the cells inside plants, but don't cause any apparent disease. Such fungi therefore appear to be ubiquitous in terrestrial plant communities, and they are highly diverse.

Forms of Fungus include the following:

Mushrooms & kin (mostly Basidiomycota)

Molds (two major groups).

Yeasts & kin (mostly Ascomycota)

Mushrooms & kin

Excellent sourcebooks include David Aurora's Mushrooms Demystified: A Comprehensive Guide to the Fleshy Fungi , and his All That the Rain Promises, and More ...: A Hip Pocket Guide to Western Mushrooms. A very good website for California mushrooms is MykoWeb. Scott Bates's website at ASU, Fungorum Arizonensis turns attention toward Arizona species. For rank beginners to the subject, the website provides a useful guide.

Most "mushrooms", "puffballs", etc. are named for their large fruiting bodies as shown at left. While the fungal group Basidiomycota is best known for these, it also includes microscopic fungi like "rust" and "smut" -- parasitic on plants -- and also some of the yeasts. So genetics and categories based on appearance do not entirely coincide. For example, the Morel, a "mushroom", falls into the Ascomycota lineage, among the "yeasts".

This mushroom at left sprang up in the wash just above the Trail Tank, shortly after the flood following a late-July thunderstorm in 2004. Scott Bates (see below) thinks this may be Coprinus calyptratus.

(Click on the image to enlarge it.)



Earth Star Mushrooms (Family Geastraceae, Geastrum spp.)

In this family of mushroom fungi, the outer peridium (the covering of the spore-bearing organ) splits into starlike segments when it dries, revealing a spherical spore-sac ("Puffball") within. Daniel Baker encountered a number of these on a shadowed hillside, in litter beneath a large 30 ft. cat-claw acacia in lower Hot Springs Canyon, where they sprouted in September following the late summer rains of 2005. All of them had four "rays" or "petals" ("arms"?). He provided this set of three for our collection. (Click on each image to enlarge it.)



Below left, a view of the base of the trio. Below middle and right, two puffballs at different stages of development.


While investigating this mushroom, Daniel Baker made contact with S.T. Bates of the School of Life Sciences at Arizona State University, whose MS Thesis, "Arizona Members of the Geastraceae and Lycoperdaceae (Basidiomycota, Fungi)", provides a systematic study of these fungi. This includes numerous photographs of various species. To us, our Geastrum above looks very similar to the fornicatum species shown on page 329. You can examine the Thesis, and other information on mushrooms as well, at the following link. Thanks to Scott Bates for this information.


Molds are microscopic, plant-like organisms, composed of long filaments called hyphae. Mold hyphae grow over the surface and inside nearly all substances of plant or animal origin. They differ from the mushrooms only in that their filaments do not combine into large fruiting bodies. When mold hyphae agglomerate sufficiently to be visible to the naked eye, the mass is called a "mycelium." For an excellent discussion of the group, see this mould site, courtesy of the New Brunswick Museum.


Yeasts & kin

Yeasts are single-celled fungi. Images of them are therefore microscopic, and we will not deal with them further on these pages, beyond observing that they are commonly found on our plant leaves, flowers, and soils, and on the skins and in the intestines of warm-blooded animals. For a link that explores the subject, see

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