Bulbous Bonnet
Mycena bulbosa
The Bulbous Bonnet is a very small agaric characterized by its pure white to pale grey color and a distinctive basal disc at the stem base. It lives as a saprobiont exclusively on dead stems of rushes, sedges, and other marsh plants. The species is strictly tied to permanently moist locations such as bogs, ditches, and riparian zones, where it contributes to the decomposition of organic matter.
Details
Identification
Cap 2-6 mm wide, whitish; stem 5-20 mm long with a small basal disc; gills narrowly adnate; spores amyloid.
Social behavior
Usually grows gregariously on the specific plant substrate.
Diet
Saprobic lifestyle; decomposition of cellulose and lignin in dead marsh plants such as Juncus and Carex.
Overwintering
Survival as mycelium within the substrate.
Ecology
Ecological role
Important primary decomposer in aquatic transition zones; promotes nutrient cycling in bogs and wet meadows.
Natural predators
Slugs, fungivorous insect larvae (fungus gnats).
Competitor species
Other specialized micro-fungi of wetlands, such as Mycena species or Marasmius species.
Ecosystem service
Nutrient recycling and humus formation in ecologically sensitive wetlands.
Threats
Melioration, drainage of marshlands, nitrogen input, and loss of rush populations.
Scientific profile
Profile
Distinguishing features
Key features include the tiny size, growth on wetland plants (Juncus, Carex), the formation of a pseudocollarium (gills attached to the stipe but often appearing as a ring), and the distinct basal disc at the stipe base. Microscopically, the amyloid spores (8-11 x 3.5-5 µm) and diverticulate cheilocystidia are diagnostic.
Habitat
Wetlands, fens, sedge marshes, riparian zones of ponds and ditches, and wet woodland areas with rush populations.
Reproduction
Sexual reproduction via basidiospores formed on four-spored basidia.
Protection & threats
Status not on standard scale
Main threats
Drainage of bogs and wet meadows, eutrophication due to nitrogen input (leading to displacement of host plants), destruction of riparian vegetation.
Conservation measures
Preservation and restoration of wetlands, avoidance of drainage measures, protection of sedge marshes and rush stands.