Distinguished by a small, umbonate pileus, poorly developed, decurrent lamellae, small subglobose to globose spores, pileo-, caulo- and cheilocystidia with a long, often branched rostrum and occurence on water-soaked stems of Phragmites australis in wetlands.
Pileus 1-5 mm across, hemispherical to convex, becoming applanate-convex, usually with a small papilla, sometimes centrally depressed or at least depressed around the papilla, margin long remaining incurved, more or less sulcate, translucent-striate, pruinose, white. Lamellae very distant, 4-7, broadly adnate to decurrent, with concave edge, sometimes veined, not always fully developed, occasionally one or two forked, white. Stipe 8-11(15) mm long, filiform, cylindrical, usually somewhat curved, pubescent particularly in lower parts, white, hyaline, with age sometimes yellowish from base upward, insititious, without basal hairs. Smell not distinct.
Basidia 18- 28 x 6-9.5 µm, clavate, 4-spored. Spores (5)6-7.5(8) x 4.5-6.5(7) µm, Q= 1.1-1.2, subglobose to globose, with a prominent apiculus, hyaline, inamyloid. Hymenial cystidia 21-40 x 6-9(11) µm, clavate, vesiculose, fusoid, subutriform, thin-walled, often with a long, thin, obtuse to subacute, sometimes branched up to 25 x 1-2 µm large rostrum. Hymenophoral trama non-dextrinoid. Hyphae of the pileipellis 3-7 µm wide, diverticulate, excrescences up to 7 x 1.5 µm. Pileocystidia abundant, similar to the cheilocystidia, with a swollen base and long, narrow, more or less flexuous, branched neck; Body 10-15 x 4-8.5 µm, neck up to 30 x 1-2.5 µm. Stipitipellis up to 4 µm wide, mostly smooth, rarely with scattered excrescences. Caulocystidia abundant, similar to pileocystidia, some branched or forked at apex, others just tapering towards a more or less acute and flexuous, simple neck, up to 55 µm long. Clamp connections present in all tissues.
Solitary or 3-4 specimens together in clusters on decaying, water-soaked stems of Phragmites australis. Summer to autumn. Known from Norway and France. In Norway only collected in the type locality but in three different years.