A Map Fungus Species
This widely distributed fungus in the family Rhytismataceae is a saprotroph of the dead leaves of various evergreen species in the PNW, typically Madrone or Pacific Rhododendron or Oregon Grape as depicted here. It is an Ascomycete that forms apothecia that are hexagonal inside bleached regions bounded by zone lines. These apothecia open when the ascospores within are mature. They are accompanied by pycnidia, tiny black structures 0.5mm or so that form asexual spores. These various structures all form within the epithelium of the decaying leaf. The zone lines are formed by antagonistic activity between different colonizing individuals within the genus. The fungus is abundant and once noticed becomes hard not to notice thereafter.