The colour of the aerial mycelium is dramatic in some cultures, but because this is a highly variable character amongst cultures of some species, it is not included as a character in this key. The colour of the back side of the colony tends to be highly variable within a species, but can be critical for a few species. Generally, a purple reverse is indicative of species in section Liseola . Red pigments are produced by species of several sections. The absence of red pigments is critical for recognizing some species.
Pigments are often more intense in colonies incubated in complete darkness.
Pigments produced on 'home made' PDA are much more intense than those produced on commerically available formulations.