The hyphal mode of growth

The dominance of filamentous fungi within the ecosystem is attributed to their common mode of growth, extending as branched filaments (hyphae) which can rapidly spread across uncolonized substrates. The success of this growth habit for exploiting the natural environment can be judged on a number of factors: the extraordinary diversity of fungal species (estimated at three million, second only to the insects), their distribution in virtually every habitat on the planet and the parallel evolution of a similar growth habit by another important class of soil microorganisms, the prokaryotic streptomycetes. Clearly the ability of a microbe to rapidly colonize new substrates by concentrating growth at its apex, is well suited for life as a heterotroph in a heterogenous environment.

Spore dormancy and germination

Spores are products of both sexual and asexual reproduction and act as units of dispersal in fungi. The majority of spores germinate to produce one or more germ tubes and a new fungal mycelium when the spore settles on an appropriate substrate under favourable environmental conditions. When a spore is faced with unfavourable conditions such as lack of nutrients, low temperature, an unfavourable pH or the presence of an inhibitor (e.g. on a plant surface), the spore remains dormant. Spores under these conditions are exogenously dormant and will only germinate when the environmental conditions become favourable.