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Arrhenia rickenii, commonly known as the Winter Navel, is a small, omphalinoid agaric characterized by its greyish-brown to blackish cap, decurrent gills, and preference for growing on mosses, particularly during colder months. It is a saprobic species, playing a role in the decomposition of organic matter associated with its moss substrate. Its distinctive appearance and habitat make it relatively easy to identify for experienced mycologists, though careful observation is always necessary.
How to Identify
- Cap
- Typically 0.5-3 cm in diameter, convex to plano-depressed, often deeply umbilicate (navel-like) in the center. The margin is often wavy or lobed, and can be translucent-striate when moist. Color ranges from greyish-brown to dark brown or blackish, often paler towards the margin, and can be somewhat hygrophanous, fading when dry. The surface is smooth, sometimes finely pruinose when young.
- Gills
- Decurrent, moderately broad, distant to subdistant, often forked or anastomosing near the stem. Color is greyish to brownish, sometimes with a purplish tint, becoming darker with age. Spore print is white.
- Stem
- 0.5-2.5 cm long and 1-3 mm thick, central or slightly eccentric, cylindrical or slightly tapering towards the base. Color is similar to the cap, greyish-brown to blackish, often paler at the apex. The surface is smooth or finely pruinose, and the stem is solid or stuffed when young, becoming hollow with age. No ring or volva.
- Flesh
- Thin, fragile, concolorous with the cap or slightly paler.
- Fruiting body
- Small, omphalinoid, with a depressed cap and decurrent gills.
- Habitat
- Saprobic, growing gregariously or scattered on mosses, particularly species of Sphagnum, but also other mosses in damp, shaded environments. Often found in bogs, fens, wet woodlands, and heathlands.
Key Facts
- Cap surfaces: Smooth, sometimes finely pruinose, hygrophanous
- Growth Form: Gregarious or scattered
- Spore Print: White
- Body color: Greyish-brown to blackish
- Odor: Indistinct
- Flesh bruises: No significant bruising reaction
- Height: 0.5-2.5 cm
- Cap Diameter: 0.5-3 cm
- Nutrient gathering: Saprobic on mosses
Safe
SafeArrhenia rickenii is generally considered inedible due to its small size, thin flesh, and lack of culinary appeal. There are no reports of toxicity, but it is not consumed. As with all wild mushrooms, positive identification is crucial, and consumption of any unidentified mushroom is strongly discouraged.
Quick Check
- Odor: Indistinct or slightly fungoid
- Fruiting: Late autumn to early spring
- Substrate: Mosses (bryophilous)
Where to Find
Europe
Widespread across temperate and boreal regions of Europe, particularly in areas with suitable moss habitats.
North America
Reported from various regions in North America, especially in the Pacific Northwest and northeastern parts, where mossy habitats are prevalent.
Asia
Occasional reports from parts of Asia, though its distribution here may be less well-documented.
Finding Tips
Habitat Focus
Look for this species in damp, mossy areas, especially bogs, fens, and wet woodlands. It is almost exclusively found growing directly on mosses.
Seasonal Timing
While its common name suggests 'Winter Navel', it can fruit from late autumn through winter and into early spring, often appearing during mild spells when other fungi are scarce.
Size and Color
Its small size and dark, often greyish-brown to blackish coloration, combined with its deeply depressed cap, are key identification features.
Decurrent Gills
Observe the gills carefully; they should run down the stem (decurrent), which is a characteristic feature of Arrhenia species.
Similar Species
Moss Navel
fungus
Also known as: Arrhenia sphagnicola
Bog Navel
fungus
Also known as: Arrhenia spathulata
Omphalina
fungus
Also known as: Omphalina species (various)
Scientific Classification
- Phylum
- Basidiomycota
- Class
- Agaricomycetes
- Order
- Agaricales
- Family
- Hygrophoraceae
- Genus
- Arrhenia
Storage Information
- Max Temperature: Not applicable
- Freezing duration: Not applicable
- Min Temperature: Not applicable
- Refrigeration: Not applicable
How to Clean
Not applicable, as this mushroom is not considered edible. If handled for identification, gently brush off any debris with a soft brush. Avoid washing with water as it is very fragile.
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