Fall Fungi - 24 September 2023

On Sunday September 24, 2023 from 1:30 to 3:00, 53 folks on the Fall Fungi Fieldtrip led by Marie Trest of the UW Department of Botany, and starting at Picnic Point Stone Gate.
 
We gathered at 1:30 at the kiosk; the weather was sunny and 76.  I collected a list of names. The participants included several families with young children, clusters of UW students, and retirees.

Marie noted that the drought over the past couple of months meant that the variety and number of mushrooms on the forest floor might be low relative to a normal year.  She explained that collecting in the Preserve is not allowed unless one has a permit, which she has.  Her approach was to allow participants to search for mushrooms for 10-15 minutes, and then we would gather together and she would talk us through the samples the group had found.  We did this at two different places, both within 100 yards of each other, both along the roadway leading into the Preserve from the Stone Gate.  With 50-some people that meant we had 100 eyes and 500 fingers looking and probing for fungi on or in the soil, on fallen logs, and on branches & leaves in the trees & shrubs.  This approach yielded an array of examples.

An array of Armillaria fungi cousins collected during the fungi search!

More fungi collected by participants during the fungi seach

These included fleshy fungi (in both ascomycota and basidiomycota) and woody ‘shelf fungi’.  The size or distribution of mushrooms is not a reliable indicator of how extensive the fungus mycelium spreads in the soil.  By one reckoning, an Armillaria fungus growing in forest soil in Oregon is the single largest organism found so far on Earth.
 
One way to help identify fungi is to take a spore print, but this technique requires several hours and is usually done in the lab more than in the field.
 
Some participants found slime molds growing on dead wood; biologists consider the slime molds to be protists rather than fungi.
 
In the woods, some fungi are saprophytes—they breakdown and rot dead wood and leaves in the forest or grasslands.  Other fungi can be pathogens that attack the leaves, stems or roots of living plants.  Significant examples of fungal diseases that have transformed our landscape include the Chestnut Blight, the Dutch Elm Disease (both are introduced pathogens) as well as Oak Wilt.  Other pathogens cause mostly just leaf lesions without much harm, such as the Tar Spot fungus of maple. 
 
If we were collecting at night, we would likely see that some fungi are bioluminescent – the phosphorescent ones can give off light called foxfire—and others are fluorescent – if you shine UV light on these, they reflect a glow at a wavelength different from the UV light you shine on them.

Friends President Will Vuyk holding a white mushroom he found in the Preserve Forest

In addition to the fungi that make fruiting bodies we call mushrooms, other fungi can produce spores (including asexual spores) directly from the hyphae or ‘threads’ of the mycelium.  Mycologists can collect airborne spores using air-sampling traps (see timepoint 6:15 of this video) followed by identifying the spores using microscopes or even by molecular techniques.
 
Furthermore, the mushrooms include yeasts, and while yeasts don’t make hyphal threads or mushroomy fruiting bodies, on occasion you can see yeast growing extensively on the cross-section wood of freshly-cut stems or trunks of pruned branches or stumps; the yeast feast on sugars that exude from the phloem of the stubs of the lopped-off branches. 
 
Finally, one participant found what at first appeared to be long white mushroom, but proved to be the flower & curved stalk of Indian pipe, which is a parasitic, colorless plant. 

Report and photos by Tom Zinnen.​​