6 Wood Discoloration

2.2 Growth and Spreading 13
Fig.2.6. Hyphae within a strand of Serpula lacrymans. H vegetative hyphae, V vessel hypha,
F fiber hyphae (dark-field photo W. Liese)
(only through the joints) between bricks or through old, crumbly bricks, and
insulation materials. In the laboratory, some house-rot fungi overgrew by
means of strands agar that contained wood preservatives (Liese and Schmidt
1976) as well the fungal partner in dual culture.
In the literature, there is however not always a uniform use of the terms
“strands (= cords)” and “rhizomorphs”. For example, the strands of the American
dry rot fungus, Meruliporia incrassata, have been termed rhizomorphs and
were described as consisting of more or less parallel hyphae, outer (cortical)
hyphae thick-walled and uniform in size (author: = fibers), inner (medullary)
thin-walled hyphae, variable in size, and some differentiated into large conducting
tubes (author: = vessels) (Palmer and Eslyn 1980). According to Burdsall
(1991) “these two (S. lacrymans, M. incrassata) being similar and unique
in forming large water-conducting rhizomorphs”.
By means of his strand diagnosis, Falck (1912) was able to differentiate some
house-rot fungi like S. lacrymans, Coniophora puteana, and Antrodia vaillantii
macroscopically and microscopically. Table 2.4 shows an updated version for
the above tree species based on recent measurements of mycelia in buildings
andonagarculturesofgeneticallyverifiedisolates.
As strand morphology is, after fruit body structure, a main feature to identify
fungigrowingindoorsoranconstructionwood,anidentificationkeyforabout
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