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6.
Basidiomycota:
This
is the group of fungi that form their spores on clubs, called basidia.
Found among these fungi are the rust and smut fungi, the jelly fungi,
mushrooms, puffballs, stinkhorns, and bird’s nest fungi. The rusts, like the one on peanuts in
this area (Fig. 2-21),
Fig.
2-21.
Leaf rust of peanuts caused by Uromyces.
and
smut fungi cause extensive damage to crop plants in all areas of the
world. Their basidia differ from those found in mushrooms (Fig.
2-22).
Fig.
2-22. A basidium of Gymnosporangium showing two sterigmata and
basidiospores.
Some
most common rusts across America are cereal rusts (Fig.
02-23)
Fig.
2-23. The wheat stem rust caused by Puccinia graminis.
and
the cedar-apple rusts (Fig. 2-24; Fig. 2-25).
Fig.
2-24. An overwintering gall of the cedar-apple rust, Gynosporangium
juniperi-virginiana.
Fig.
2-25. The telial stage of the cedar-apple rust.
Cedar-apple
rusts require two hosts on which to complete their life cycle. Spores
from the sexual stage on cedars blow to apples and form asexual states
on young fruits and leaves (Fig. 2-26).
Fig.
2-26. The aecial stage of the cedar-apple rust on apples.
Smuts,
so named because of their masses of sooty spores, are a problem to corn
and other cereal crops, but
in Mexico, smutted corn is considered a food delicacy (Fig.
2-27).
Fig.
2-27. The corn smut Ustilago maydis.
The
jelly fungi are common saprobes, but we will see in a later
chapter that they are also cultivated for food (Fig. 2-28).
Fig.
2-28. The common jelly fungus Tremella foliacea.
The
ear fungus, another jelly fungus, has important medical qualities
(Fig. 2-29).
Fig.
2-29. The ear fungus Auricularia auriculata.
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Some
coral fungi (Fig. 2-30), so named because of their appearance,
are also edible, and some may be mycorrhizal with tree species.
Fig.
2-30. A common coral fungus, Clavulina
gracilis.
Most
large fleshy fungi belong to the bracket fungi or mushrooms.
We will learn later in the course that the bracket fungi, commonly
called polypores, are the chief decomposers of cellulose and are
important as wood-rotting fungi. Common bracket fungi are found on the
sides of decaying trees (Fig.
2-31)
and many will bear pores on the under surface (Fig.
2-32).
Fig.
2-31.
The bracket fungus Trametes versicolor.
Fig.
2-32.
The pore structure found in a large variety of bracket fungi.
There
are all sorts of bracket fungi, or what we call
polypores, because most have pores not gills on which the spores are
found. One of the polypores
that you will hear considerable about in the course is Ganoderma,
the varnish-skin fungus.
Mushrooms
are very important in that many are used for food, others are deadly
poisonous, and many are beneficial to trees. One of the most common
toxic groups in the U.S. is Chlorophyllum molybdites (Fig.
2-33) that often forms
fantastic fairy rings on lawns and golf courses.
Fig.
2-33. A large fairy ring formed by Chlorophyllum molybdites.
Gasteromycetes
(gastero=stomach; mycetes=fungi) form their spores internally. In this
group we find the puffballs (Fig. 2-34),
Fig.
2-34. The giant puffball Calvacia giganteae.
stinkhorns
(Fig. 2-35),
Fig.
2-35. A common stinkhorn Dictyophora duplicata, contaminated by
one of the bread mold fungi.
birdsnest
fungi (Fig. 2-36),
Fig.
2-36. Crucibulum vulgare, a common birdsnest fungus.
and
Clathrus, the fungus flowers (Fig. 2-37).
Fig.
2-37. Clathrus cancelllatus, commonly referred to as the fungus
flower.
7.
Deuteromycota:
These are
Ascomycetes and Basidiomycetes that only reproduce by asexual spores, or
their sexual stages have never been found. The Deuteromycota is an
artificial taxonomic group designated to include conidial-producing fungi. These
are the fungi we commonly refer to as mold and mildew because they
normally form extensive mycelium with powdery spores. They are probably
the most important group of fungi because of their abundance and
widespread occurrence.
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