For some time we have been discussing fungi within the phylum Basidiomycota, the club fungi.
Within this phylum, let us now move further into the class Agaricomycetes,
which consists of many of the mushroom-forming species of fungi, and more specifically,
the order Agaricales, which consists of many of the gilled mushroom species. In this tutorial, we
will be introducing a number of new types of these fungi, including the families Cortinariaceae,
Nidulariaceae, and Psathyrellaceae, along with the genera Conocybe and Laccaria.
Let’s begin by discussing the Cortinariaceae family. Generally, this family describes fungi
in the genus, Cortinarius, which is the largest genus of mushroom-forming species,
estimated to have over 2000 thousand species worldwide. The notable structural characteristic
of this genus is the presence of a cortina, a web-like partial veil that covers the gills
of the mushroom when young. As the mushroom ages, the remnants of the cortina may form a ring on the
stipe or along the margin of the cap. The gills produce a rusty-brown spore print, so the gills
of Cortinarius mushrooms are generally rusty-brown as well. These mushrooms are not purely saprobic,
so throughout their life cycle, they do not always need to break down organic matter to survive.
Instead, they form mutually benefitting relationships called mycorrhiza, “myco” meaning
fungi and “rhiza” meaning root. So, mycorrhizal relationships form between fungi and plant roots.
A number of fungi form mycorrhizal relationships of different types. However, when fungi in
the phylum Basidiomycota form mycorrhiza, they specifically form ectomycorrhiza. Structurally,
ectomycorrhiza have the root system completely surrounded by a layer of hyphae called a mantle.
Some of the hyphae penetrate the outer layer of the root forming a network called the Hartig net.
The Hartig net allows the fungus and the plant to become closely connected, allowing
for the exchange of nutrients such as sugars, nitrogen-containing compounds, and amino acids.
Many other mushroom genera we will discuss throughout this series
form ectomycorrhizal relationships. Our next family is quite fascinating. This is
Nidulariaceae, commonly known as the Bird’s Nest fungi, because their fruiting bodies
look like tiny egg-filled bird’s nests. The name comes from the latin root “nidus” meaning
nest. These fungi are saprobic on decaying wood, so you are likely to find these adorable fruiting
bodies on wood chips or mulch. Fungi in the family Nidulariacae have unique structures.
We previously discussed the gasteroid puffballs of Agaricaceae. Bird’s nest fungi are also
gasteroid because they develop their spores inside those small egg-like structures called
peridioles. These peridioles have their basidia and basidiospores surrounded by a hardened wall.
The nest-like structure that houses the peridioles is called the peridia. All Bird’s Nest fungi have
an interesting method of dispersing their peridioles, and therefore their spores. The
nest-like peridia act as splash cups. When a raindrop hits the peridia slightly off-center,
the raindrop expels the peridioles up to a meter away. Two out of the five genera in the family
possess tendrils called funiculi that are attached to the peridioles. When the peridioles are
expelled from the peridia, the funiculi can wrap around a plant nearby. It is hypothesized that
herbivores will eat the plant and the attached peridiole, assisting in further spore dispersal.
Now let us move to a family that has the general structure of a gilled mushroom with a cap,
gills, and a stipe, the family Psathyrellaceae. We will discuss three genera in this family:
Coprinellus, Coprinopsis, and Psathyrella. Fungi in Psathyrellaceae are almost always saprobic.
You can find these fungi on soil, dung, decaying wood, and many other substrates.
The fruiting bodies are generally small and fragile with dark-colored spores.
Let’s begin our discussion of Psathyrellaceae by discussing the similar genera,
Coprinellus and Coprinopsis, commonly known as the ink caps. The common name originates from a
unique property of these mushrooms. As they age, the gills partially liquify or deliquesce into a
black goopy and ink-like substance. This process is already quite captivating, but it is another
demonstration of the genius of evolution. The caps of these mushrooms liquify from the edges in,
so the maturing spores at the inner parts of the cap are in prime position to catch
wind currents to disperse. Identification on the species level is quite difficult for two reasons.
The first is that these mushrooms are extremely fragile and ephemeral. Over a single day,
some species will fruit, deliquesce, and reduce to almost nothing. So it is quite difficult to
gather the mushrooms as specimens. Second, the separation of Coprinopsis and Coprinellus species
may require microscopic and genetic analysis. Coprinopsis atramentaria, or the common ink cap,
is known to be edible, but contains a molecule called coprine that causes poisoning when
consumed within a two to three day time period of drinking any form of alcohol. This has caused some
confusion with Coprinus comatus, the shaggy mane mushroom we discussed in the Agaricaceae lecture.
This mushroom does not contain coprine and does not lead to alcohol-induced poisonings.
Our next genus in the family Psathyrellaceae is Psathyrella, commonly called the brittle stems.
These mushrooms are small and fragile. They produce black to brown spores and do not
liquify like the aforementioned genera. The stipes are whitish to yellow and hollow on the inside,
allowing them to have a satisfying snap. The caps are generally brown and often times hygrophanous,
meaning the caps change color as they lose moisture. Identification on the species level
generally requires microscopy. In Haitian tradition, species of Psathyrella are highly
valued as a delicacy. Called Djon-Djon, the caps of these mushrooms are served at important events
such as baptisms and weddings. Djon-Djon is generally boiled and strained. The Djon-Djon
water is used to flavor cooked rice. Because these mushrooms can be quite expensive and rare,
djon-djon flavored bouillon cubes are commonly used as a replacement for these dishes.
Now we will move away from Psathyrellaceae to discuss the genus Conocybe, commonly
known as the dunce-caps due to their conical or bell-shaped caps. They are small, fragile,
usually brown mushrooms that are saprobic on grass and other substrates. A common species of Conocybe
is Conocybe apala, a mushroom that notably fruits in grass lawns. The mushroom is toxic but not
lethal, so keep your pets and children away. It has a pale brown color, and you will find the
mushroom when the weather is hot and humid. The last genus we will discuss is Laccaria.
These mushrooms are easy to recognize as they have thick and waxy looking gills that are attached to
the stipe. They form white spore prints, and under a microscope, these spores are round with tiny
spine-like projections. All Laccaria species form ectomycorrhizal relationships that are generally
associated with tree roots in the order Fagales, which houses oak and beech trees. A notable
species in the genus is Laccaria amethystina, or the amethyst deceiver. The name originates from
difficulties in identification of the mushroom because the bright purple coloring fades with age.
Let us now move forward and continue to examine still more species within Agaricales.