6 Wood Discoloration

2.5 Classification 49
with about 120,000 species may be grouped into three divisions and a form
division: Zygomycota, Ascomycota with the classes Endomycetes (yeasts) and
Ascomycetes, Basidiomycota including the Basidiomycetes, and Deuteromycota
(Deuteromycetes).
The important fungi that inhabit or destroy wood belong to the Ascomycetes,
Basidiomycetes, or Deuteromycetes. Ascomycetes and Basidiomycetes have in
common a dikaryotic phase and a haploid phase as mycelium, which does not
sprout yeast-like.
About 30,000 Ascomycetes (additionally about 16,000 lichen fungi) are characterized
by the development of the meiospores in asci, the restriction of the
dikaryon to the ascogenic hyphae in the fruit body, and the predominant
gametangiogamy. In the Basidiomycetes (about 30,000 species), the mature
meiospores are located in the sterigmata, and after somatogamy the dikaryotic
phaseisextendedtothemycelium.
As the third artificial group, the Deuteromycetes (30,000 species) are added
whose vegetative characteristics correspond to the Ascomycetes or Basidiomycetes,
in which, however, a teleomorph is not yet known or is either
temporarily or generally not present.
The term “microfungi” covers the Deuteromycetes and some Ascomycetes
with microscopic structures. “Macrofungi (macromycetes)” means Basidiomycetes
and Ascomycetes with large fruit bodies.
There are different classifications of the Ascomycetes. A traditional way
considers the appearance of the fruit bodies (ascomata): Hemiascomycetes
(Protoascomycetes) do not form fruit bodies, Plectomycetes have protothecia
or cleistothecia, Discomycetes show apothecia, Pyrenomycetes own perithecia,
and Loculoascomycetes form pseudothecia (Schwantes 1996; Fig. 2.14).
Another differentiation groups the Ascomycetes according to the time of development
of the fruit bodies in the two groups, euascohymenial Euascomycetes
and ascolocular Loculoascomycetes. In the first, the fruit body develops after
the gametangiogamy, and in the latter, the primordia develop before the
gametangiogamy. With priorization of the wall structure of the ascus, the
Lecanoromycetidae show ascohymenial ascomata and a primitive archaeascus,
the Euascomycetidae comprise ascohymenial fungi with a prototunicate
Table 2.11. General classification of fungi
Protista (2,000 species): Six divisions (e.g., slime fungi and “lower fungi”)
Fungi (“higher fungi”), 120,000, three divisions and one form division:
1. Zygomycota
2. Ascomycota: yeasts and Ascomycetes, 46,000 (lichens included)
3. Basidiomycota: rust fungi, smut fungi and Basidiomycetes, 30,000
Deuteromycota: Deuteromycetes (imperfect fungi), 30,000
with relevance to wood: Ascomycetes, Basidiomycetes, Deuteromycetes
www.taq.ir