Observation 292785: Rimbachia Pat.

Small white mushroom growing most commonly in living or dead moss (Sphagnum and other species), but also found on the ground in bits of other plant debris, including small pieces of birch bark, deciduous leaves and tiny rotting twigs (but not on logs). Caps very thin, largest 2 cm but the rest 3-10 mm, oyster-shaped, edges sometimes becoming frilly with maturity. Smooth gills, very short or no stem. “Fuzzy” with mycelium at attachment point to substrate. Spore print white. Spores tear drop shaped, (4.4)5-6.8(8.9) x (3)3.1-4.3(5.6). Means 5.8 (SD 0.6) x 3.7 (SD 0.4), n = 113.


The largest specimen I found, about 1 cm x 2 cm, growing in dead Sphagnum.
Gills on the largest specimen
On rotting leaves
On bark
On a twig
On plant debris
On living moss
In moss
Spores in water.
pileus with 40x objective (by TJB)
pileus with 100x objective (by TJB)

Proposed Names

27% (1)
Recognized by sight
5% (2)
Recognized by sight
-12% (2)
Recognized by sight
62% (3)
Used references: Consulted with Timothy Baroni and Scott Redhead. Species still undet.

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= Observer’s choice
= Current consensus


Add Comment
By: Jacob Kalichman (Pulk)
2018-03-04 06:29:14 PST (-0800)

Sue, did Timothy or Scott suggest any Rimbachia species besides R. bryophila? That’s the only substantially lamellate NA species I could find.

By: Sue Lancelle (SueLan)
2017-09-30 11:53:35 PDT (-0700)

I had considered this but ruled it out based on habitat (I’ve found Cheimonophyllum before, always on rotting logs) and spore shape (pictures and descriptions indicate Cheimonophyllum has globose spores).