FUNGAL SPORES: Unicellular or multicellular, reproductive or
distributional cells developing into a number of different phases
of the complex life cycles of the fungi. Fungal spores can be
readily classified by the Saccardian system, which relies
on the number, shape, and placement of spore cells to classify
the fungi imperfecti. Most fungal spores in pollen preparations
probably are phaeospores (dark spores) of the fungi imperfecti,
rather than ascospores, basidiospores, or spores of the lower fungi.
However, repeating (asexual) spores of the basidiomycetes are
very common in some sites. Wolf (1969) demonstrated that dark
fungal spores are more resistant to acetolysis than clear ones.
Examples of the importance of fungal spores in palynology include the forms Helminthosporium and Alternaria that are common in aeroallergy studies. The dung fungus Sporormiella is an indicator of herbivore density, and has been shown to increase in historic times after the introduction of grazing animals, and before 11,000 years ago -- prior to megafaunal extinction (Davis, 1987; Davis and Shafer, in press). In the American Southwest, the decay fungus Tetraploa is very abundant in historic sediments due to increased abundance of senescent plant tissue in freshwater marshes (Davis, 1995).
The spores of various wheat and corn pathogens, notably
Tilletia and the uredeospores of rusts and smuts are common
in the historic period in southeastern Washington (Davis, et al., 1977).
Thecaphora is a pathogen on Fabaceae and Caryophyllaceae that
becomes common during the historic period in the California
grasslands, perhaps due to the spread of the pathogen by over-
grazing (Davis, 1992).
More generally, dark, thick-walled fungal spores of the fungi imperfecti are common in soil samples, such as those often studied in archaeological palynology. These same forms occur in abundance equal to that of terrestrial pollen when soil is washed into aquatic basins by watershed erosion, particularly after fires or intense human disturbance (Bradbury & Waddington, ; Davis et al., 1977).
Geoscience & Man, and Palynology:
Owen Davis 12/99