culture of Armillaria mellea. Note the creeping "rhizomorphs".
Rhizomorphs are "rootlike" structures composed of dense bundles of mycelium,
which aid in the survival, and spread of the fungus. The dark pigment
is melanin which helps protect the mycelium.
mellea grown on PDY agar for 21 days @ 25 degrees Celsius
mellea grown on rye grain for 40 days @ 25 degrees Celcius
mellea is not the brightest glowing species on agar culture, however
on wood substrates, the mycelium is reported to glow much brighter.
The phenomenon has been referred to as "foxfire" or "willow the wisp".
Armillaria is a pathogen of trees; whole forests can be wiped out
he invading fungus, leaving "ghost" trees. Rhizomorphs form
extensive underground networks, and genetically identical colonies have
been known to cover areas equivalent to several football pitches, making
this species the largest organism on earth!