A Glimpse of Nature -- Gills & Pores
October 15, 2021
This week, let’s look at a few of the fungi that have been growing around the Ames Free Library. Rather, I should specify that we’ll be examining their fruiting bodies. After all, the inconspicuous mycelia of these fungi have been growing there all along . . . but we’ll get to that another day.
The fruiting bodies are the parts that produce spores, the reproductive cells that will, with appropriate conditions, become new fungi. The most familiar of these, the ones with stalks and caps, are what we usually call “mushrooms.” Here’s a specimen that was growing near the rear parking lot of Queset House, not far from some hemlock trees. It has a convex cap with a depression in the center. The shape of a mushroom’s cap and its texture can help identify it.
Caps can be convex or concave or nearly flat, cone or funnel shaped, broad or petite. Their surface may be dry and powdery, or sticky, or covered with warts or scales. For comparison, look at the caps of the two mushrooms below. The fungus on the left, a viscid violet cort, has a sticky cap. The amanita on the right displays white warts.
Here’s the underside of the Queset mushroom. Its gills are plates of tissue that radiate out from the stalk. The structures that produce spores, the basidia, are along these gills. Notice the spacing of the gills and their attachment to the stalk. Some of the gills have separated as the mushroom decayed.
Observe the spacing of gills on the next two species. On the left, the mushroom’s gills are so close that they seem to form a smooth surface. On the right, full-length gills are separated by partial gills at the cap’s edge, all of which are clearly visible.
If you handle a mushroom, pay attention to its texture. The gills of our sample mushroom break easily: it’s in the genus Russula or “Brittlegills.” Other gills may feel waxy.
Similarly, stalks can be delicate or solid, slender or stout, evenly cylindrical or bulbous. The profiles of the next two species are dramatically different because of the ratio of stalk to cap.
Here’s a species that has just started coming up at the library. These gilled mushrooms display another useful identifying feature: a ring of tissue on the stalk that is a remnant of a partial “veil” that protected the gills of the young mushroom.
Here is the same fungus two days ago, at a time when the gills were still covered.
In late September, old man of the woods mushrooms were growing near the brittlegills
This handsome fungus belongs to a completely different order: the boletes. The caps of boletes contain pores rather than gills, and their spores are released through these miniscule tubes. Here’s another specimen which I photographed closer to my home. At this angle, the pores are clearly visible. Note, also, the prominent scales which cover the cap.
Most boletes are not dark and scaly. The photos below depict some common forms and colors.
The layer of pores on boletes is soft and spongy unlike that of most shelf mushrooms. From above, the caps look like small cushions or muffin tops. The underside reveals the pores.
The color of a mushroom’s spores is a useful diagnostic for both boletes and gilled mushrooms. To take a spore print, remove the stem and place the cap on a white sheet of paper. Leave overnight. Compare your mushroom’s print to the spore descriptions in a good field guide
One can find a nice description of the process, and a whole lot more, on mushroomexpert.com. The site’s creator uses microscope slides to capture his prints, which facilitates examination of the spores under magnification.
There is much to learn. This post has introduced just a small part of the fungal world. In the process of highlighting some of the diagnostic features of gilled mushrooms and boletes, I have been speaking as if the organisms live in isolation. In reality, their connections to surrounding lifeforms are incredibly complex. For starters, some fungi form mycorrhizal relationships with plants -- mutually beneficial connections of plant roots and fungal hyphae where minerals and sugars are exchanged. Some mycorrhizal fungi are affiliated with particular plant species. That is where they grow, that’s where their tree species thrives, and that is where you, the mushroom observer, will find them. The painted suillus, for example, grows under eastern white pines. When you spot fungi, notice which trees are nearby.
One place to start learning about these relationships is through an online publication by the US Department of Agriculture entitled Field Guide to Common Macrofungi in Eastern Forests and Their Ecosystem Functions. Another resource is The Audubon Society Field Guide to North American Mushrooms which includes the habitat for each species -- the substrate upon which it grows and its natural community.
Another obvious relationship is between fungi and the animals who eat them. Many of the mushrooms that I’ve found have missing pieces and “bite” marks, or they have been left in shreds. Often enough, there are slugs and insects on the mushroom itself. These animals are consuming nutrients that fungi have made available, often through their ability to decompose dead matter.
According to that USDA guide, “Boletes are important food for insect larvae, invertebrates, turtles, snails, slugs, and many mammals, especially squirrels who often store the mushrooms in trees.” So, when you search for mushrooms, you’ll also need to pay attention to trees, insects, mammals . . . and the rest of the forest.
During the coming year, A Glimpse of Nature will consider other aspects of this subject. Your mission this week is to find 5 different species of gilled fungi and 5 species of boletes. Bring a hand lens and a camera. Borrow a field guide if you don’t already own one. And, if you haven’t submitted a photo to the Fabulous Fungi Challenge, there is still time. Email images to firstname.lastname@example.org. Happy hunting!
At the library:
by David Aurora
by Gary Lincoff
by Alan Bessette