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Fungi

Some 50,000 species of fungi have been identified, but the true number is probably many times larger.

Characteristics of Fungi

Ascomycetes (Phylum Ascomycota)

Ascomycetes produce two kinds of spores: Some notable examples:

Lichens


The lower image is of the colorful lichen called British soldier.

Phylogenetic trees, based on both ribosomal RNA genes and many protein-coding genes, as well as fossils indicate that lichens have been present on the earth for at least 600 million years.

Today about 14,000 species of fungi form lichens.

Lichens are extremely sensitive to air pollution. One of the best contemporary examples of evolutionary adaptation is the change in coloration of the peppered moth as the lichens in its habitat declined because of air pollution and then returned when air quality controls were put in place. Link to an illustrated discussion.

Some modern fungi (e.g., Penicillium chrysogenum, the source of the antibiotic penicillin) appear to have evolved from lichen-forming ancestors — abandoning their original symbiotic way of life.

Basidiomycetes (Phylum Basidiomycota)

Basidiomycetes include mushrooms, shelf fungi, puffballs, rusts, and smuts. They are dispersed by spores borne at the tips of basidia (giving rise to the name for the group).

Mushrooms are masses of interwoven hyphae growing up from the main mass of the mycelium growing underground. The basidia develop on the undersides and release their spores (four from each basidium) into the air.

A single mycelium may expand outward year after year as its hyphae grow into new terrain. In some species, mushrooms are sent up once a year at the periphery producing a circle known since medieval times as a "fairy ring".

Some notable basidiomycetes:

Zygomycetes (Phylum Zygomycota)

All the fungi assigned to this group (which probably does not represent a single clade) form spores in a sporangium. Some notable examples:

Chytrids (Phylum Chytridiomycota)

This small group (~1000 species) is thought to be the most primitive of the fungi. Unlike all the other fungi, its members produce flagellated gametes (for sexual reproduction) and flagellated zoospores (for asexual reproduction). They are mostly aquatic.

Two species are responsible for the recent worldwide decline in amphibian populations (frogs, toads, and salamanders).

External Link
An illustrated site devoted to the fungi.
Please let me know by e-mail if you find a broken link in my pages.)
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14 December 2014