So far in this series, we have discussed two of the subphyla within the phylum Basidiomycota.
These are the pucciniomycotina, commonly called rust fungi, and the ustilaginomycotina commonly
called smut fungi. The current remaining subphylum of the Basidiomycetes is Agaricomycotina, and it
represents most of the macroscopic mushrooms, such as gilled mushrooms, boletes, polypore mushrooms,
jelly fungi, and more. Agaricomycotina is split into three classes: Agaricomycetes,
Tremellomycetes, and Dacrymycetes. Agaricomycetes represent most of the aforementioned mushrooms,
while Tremellomycetes and Dacrymycetes represent the classes of jelly mushrooms.
Witch’s butter or Tremella mesenterica, a species from the tremellomycetes, is an edible
orangish yellow jelly fungus that parasitizes another mushroom. Jelly fungi represent about 2%
of the diversity within agaricomycotina. There are thousands of unique varieties of mushrooms
within the agaricomycetes. This fungal class also houses some of the most interesting fungi. The
main structural types of fruiting bodies that are produced in Agaricomycetes include gilled, pored,
toothed, coral, labrinthoid, crust-like or enclosed types of fruiting bodies.
The first order we will discuss is the most well-known of all the Agaricomycetes,
the Agaricales. Fungi within Agaricales are some of the most well-known, including the edible
white button mushroom, and bioluminescent Jack-O-Lantern mushroom. Many of these
mushrooms have a lamellate or gilled hymenophore. Starting with the family Agaricaceae, this large
family has many common and notable mushrooms that you are likely to see in your day-to-day life.
You’ll be able to find these mushrooms in grassy fields, mulch patches, local markets, and many
other places. Most of the species are saprobic, or break down organic matter found in wood or soil.
Within Agaricaceae, the white button mushroom and the portabella mushrooms are the most commonly
cultivated mushrooms in the world. These two mushrooms are actually the same species,
Agaricus bisporus. Cremini mushrooms are less mature portabella mushrooms. The portabella
variety is brown because of a single gene variant in the white button mushroom. Mushroom
cultivators take advantage of the saprobic properties of Agaricus bisporus by spawning the
mushrooms on a sawdust or grain-based substrate. A substrate is the medium a mushroom mycelium uses
to break down into digestible nutrients. The name Agaricus bisporus originates from the number of
spores produced on each basidium. Usually basidiomycetes will produce four spores per
basidium, but Agaricus bisporus only produces two. Many mushrooms in the Agaricus genus,
including Agaricus bisporus, have gills that are free from the stipe, and the gills are close to
crowded. Another common Agaricus species is the field mushroom, or Agaricus campestris.
This is an edible mushroom that can be found in grassy fields worldwide. Similar to Agaricus
bisporus, Agaricus campestris has brown gills when mature, possesses a partial veil,
forms a brown spore print, does not possess a universal veil or volva, and has free gills. These
mushrooms are edible, but beware, as there are many poisonous mushrooms that look quite similar.
Agaricus xanthodermus is a poisonous mushroom that looks very similar to Agaricus campestris,
but it stains yellow, meaning its color changes from white to yellow when damaged or cooked.
It also has a smell resembling chemicals found in ink or soap. Another very poisonous look-alike of
Agaricus campestris is the green-spored parasol, or Chlorophyllum molybdites, responsible for the
most mushroom poisonings in North America. It causes extreme diarrhea and vomiting in tandem.
The mushroom has white gills and produces a green spore print. The cap is white in color but also
has brown scales, which Agaricus campestris does not possess. A notable feature of each of the
aforementioned grassy field mushrooms is that they form distinct fairy rings, or bunches of fruiting
bodies that form arcs or rings. This interesting phenomenon, already circular in nature, is also
surrounded by folklore across Europe. In Britain and Ireland, it is said that when a human enters
a fairy ring, they will find a group of elves and fairies dancing. This human is then compelled to
dance with these ephemeral creatures until he or she perishes from exhaustion. There are many other
tales of supernatural fairy rings around the world including devils, dragons, and witches.
Although folklore is quite fantastical, the true ephemeral creature you find when entering a fairy
ring is the fungus itself. Under your feet is a network of mycelium that has expanded outward from
a central point, creating a circle. Under certain conditions, the mycelium will produce fruiting
bodies at the edge of the circle, generating the momentous phenomenon of a fairy ring.
Let us now shift our focus from circles and rings to spheres.
Notable mushrooms within the Agaricaceae family form spherical fruiting bodies. These
mushrooms are commonly known as puffballs. Unlike most species in the order Agaricales,
puffballs do not possess gills. Instead, puffballs produce a mass of spores inside the fruiting body
called a gleba. Fungi that produce spores inside the fruiting body are known as gasteroid fungi,
and fungi that produce spores in gills are known as agaricoid fungi.
During the early stages of puffball development, the gleba inside of the puffball consists of
a mass of white hyphal tissue. As the fruiting body matures, the basidia release basidiospores
shifting the gleba to a central dry spore mass. Eventually, the outer portion of the fruiting
body dries and cracks, leaving a means by which spores can escape. Most mushrooms within the
subphylum agaricomycotina spread their spores via wind, with spores being expelled from an
air-exposed hymenophore such as gills or pores. However, puffballs lack a spore surface open to
the outside environment. Instead, these mushrooms use raindrops that hit the outer surface of the
mushroom and cause a cloud of spores to puff out into the air. Puffball spores are also
spread by humans that enjoy squeezing the fruiting bodies to see a grand puff of billions of spores.
Two notable species of puffballs within the order Agaricales are the common puffball and the giant
puffball. The gem-studded puffball, or Lycoperdon perlatum, has a small white fruiting body covered
in small dart-shaped warts. As the mushroom ages, the color shifts from white to greenish brown
and a central hole forms. The spores are spread from the impact of rain hitting the mushroom,
creating a puff of spores with each raindrop. The mushroom is saprobic and is commonly found
in woods, grassy areas, and mulch piles. Because of its pebbled white appearance and distribution,
Lycoperdon perlatum has likely confused a number of amateur golf players. Another true puffball
is the giant puffball, or Calvatia gigantea. This mushroom fruiting body is highly sought
after by foragers because it is edible when young and provides a large yield of food. However,
as it matures it turns yellow or brown and becomes inedible, eventually forming a large mass
of trillions of dry spores. Sometimes humans will kick the mushroom into smithereens thinking it was
an old soccer ball. Instead, they have assisted in spreading trillions of giant puffball spores.
Another gasteroid fungus that is in the Agaricaceae is the puffball agaric, or
Endoptychum agaricoides. This mushroom is notable because it represents the evolutionary transition
from a regular gilled mushroom to a gasteroid fungus, like the Lycoperdon or Calvatia species.
When cut open, you can see two spore masses on either side of a central stalk. This mushroom
resembles an immature gilled mushroom. However, instead of opening up like a gilled mushroom, it
stays closed and dries out like a puffball. These mushrooms that are in the process of becoming a
gasteroid fungus are known as secotioid fungi. Let’s now transition back to gilled mushrooms.
To finish the family agaricaceae, we’ll discuss the Lepiotoid and Coprinus mushrooms. Coprinus
mushrooms are commonly known as shaggy mane or lawyer’s wig mushrooms because of the shaggy
appearance on the cap, and as the mushroom matures and dries out, the outer edges of the cap dissolve
into a black goop that resembles ink. As expected, this mushroom produces a black spore print,
and perhaps unexpectedly is edible when young. The genus Coprinus means “living on dung”, and these
can be found doing precisely this in some species. Initially, Lepiotoid mushrooms were all placed
into the same genus. However, recent developments in phylogeny have caused the genus to split into
many new genera. Generally, the features of these mushrooms are quite similar,
and they all have free gills and a partial veil that leaves a ring zone on the stipe. They also
have a white spore print. Some species can be quite difficult to identify because there is still
growing knowledge of lepiotoid mushrooms around the world. The parasol mushroom, or Macrolepiota
procera, is an edible mushroom that looks quite similar to Chlorophyllum molybdites, and this
similarity has caused serious mushroom poisonings. Macrolepiota procera has a longer stipe and has
a more brownish color. It also does not produce a green spore print like Chlorophyllum species.
To review, we have just discussed mushrooms in the family of fungi within the order Agaricales.
We discussed a number of mushrooms under the genus Agaricus, such as the button mushroom,
Agaricus bisporus, and the field mushroom, Agaricus campestris. We discussed gasteroid fungi
including the giant puffball, Calvatia gigantea, and the common puffball, Lycoperdon perlatum. We
also depicted the evolutionary transition from free-gilled agaracoid fungi to closed-gilled
gasteroid fungi, through the secotioid fungi, Endoptychum agaracoides. Lastly, we discussed
Lepiotoid fungi including the edible parasol mushroom, Macrolepiota procera, and the poisonous
mushroom, Chlorophyllum molybdites. Let’s move forward and look at more of this order now.