this applies mainly to the cooler regions of the world,
because most tropical and subtropical trees have
arbuscular-mycorrhizal fungi. Common examples of
mycorrhizal fungi found in the cooler regions
include species of Amanita, Russula, Cortinarius, Boletus,
Hebeloma, Lactarius, etc. They play major roles in facil-
itating the uptake of mineral nutrients from soil. But,
whereas the arbuscular mycorrhizal fungi of most land
plants seem to be involved primarily in the uptake of
phosphates from soil (Chapter 1), the ectomycorrhizal
fungi of forest trees (excluding the tropics and sub-
tropics) seem to be most significant in degrading
soil proteins and providing the trees with nitrogen
(Chapter 13).
Several members of the Basidiomycota are grown
commercially as mushroom crops (e.g. Agaricus bisporus,
Volvariella volvacea, Lentinula edodes), while others are
“cultivated” by insects to provide a food source for
the insect colonies. Two classic examples of this are
seen in the “fungus gardens” of the leaf-cutting attine
ants (Attaspecies) and in a sub-family of termites that
lack cellulolytic bacteria in their guts. In both cases,
the insects obtain their main food source by bringing
pieces of leaf or other material into the nests and
inoculating this with spores of basidiomycetous fungi.
The insect colony then feeds on the fungal hyphae, and
weeds-out any contaminant fungi. Cladistic analysis has
traced the origin of these mutualistic associations to
about 50–60 million years ago (Chapter 13).
Other members of the Basidiomycota, such as
Amanita phalloides– “the destroying angel” – produce
deadly toxins that bind to the cytoskeletal proteins
in cells. These toxins have become important
tools in cell biology for investigating cell dynamics
(Chapter 3).34 CHAPTER 2
Fig. 2.21Basidiocarps of one of the bird’s nest fungi (genus
Cyathus), about 1 cm diameter. These fungi are commonly
seen in soil enriched with wood chippings. The small
gray-brown cups open at maturity by rupture of the
thin upper membrane (see arrows), revealing a cluster
of egg-like peridioles. The basidiocarp acts as a splash
cup. When raindrops hit the peridioles these are flung
out of the cup, but each periodiole is attached to a thin
funicular cord, with a sticky hapteronat its base, and
this attaches to any object that it strikes, such as a leaf
blade.Fig 2.22(a,b) Earth stars (Geastrum
spp.), about 6 cm diameter, growing in
leaf litter beneath birch trees. These
basidiocarps are like puffballs, but are
initially enclosed in thick outer wall
layers. These layers split and curl back,
helping to raise the basidiocarp above
the leaf litter. Basidiospores develop
and mature within the closed fruit-
body, which then develops a pore at
its tip. The spores are “puffed” through
this pore when raindrops hit the papery
casing of the “spore chamber.”(a)(b)The diversity of fruiting bodies (basidiocarps)
produced by Basidiomycota
As a means of illustrating the considerable diversity of
form and function of basidiocarps, a range of examples
are shown, with annotations, in Figs 2.21–2.32. All these
examples can be downloaded in color, on the accom-
panying website for the book (see Online Resources).FB4eC02 04/20/2005 02:52PM Page 34