On bark and decayed coniferous wood (typically Pinus), often on small bark fragments deep in grass. It seems to have a tendency for occurence on alkaline soils. Late summer to autumn. Rather rare or very rare (but easily overlooked) in most of the area, but apparently more frequent in the alpine area in the extreme southern part of the area covered. Rare in Norway, and listed as DD in the Norwegian red list (2021).

Pileus 2–5(-10) mm across, covered with a (separable), gelatinous pellicle, at first globose, then hemispherical to parabolical, becoming convex, sometimes centrally somewhat depressed, but also with a small papilla, translucent-striate, sulcate, pruinose, glabrescent, somewhat lubricous, initially pale brown, then pale grey with darker centre, becoming white with age. Lamellae 9–14 reaching the stipe, ascending, sometimes fairly broad and sometimes more narrow, narrowly adnate to fairly broadly adnate or almost free, sometimes with a pseudocollarium, whitish or pale grey with whitish edge which is separable as an elastc-tough thread. Stipe 5-30(-70) x 0.5-1 mm, flexuous, terete, hollow, equal except for the base which is usually somewhat bulbous, entirely puberulous, glabrescent in the middle part, pale grey to hyaline-white; the base hirsute, sky blue (also in the flesh), springing from a patch of fine, radiating, white fibrils. Odour none. Taste not recorded.

Basidia 18-25 x 6.5-11 µm, clavate, 4-spored, with sterigmata 5-8 µm long. Spores 6.5-9 x 4-5 µm, Q 1.6-2.2, Qav ≈ 1.8, pip-shaped to somewhat elongated, smooth, amyloid. Cheilocystidia 9-20 x 5.5-7 µm, embedded in gelatinous matter, clavate to obpyriform, with few, simple to branched excrescences 3-14 x 1-1.5 µm. Pleurocystidia absent. Lamellar trama dextrinoid, vinescent in Melzer's reagent. Hyphae of the pileipellis 1.5-3.5 µm wide, embedded in gelatinous matter, very branched, covered with scattered, simple to branched excrescences, protruding through the gelatinous layer. Hyphae of the cortical layer of the stipe 1-3 µm wide, smooth, with caulocystidia up to 60 x 7 µm, simple to furcate or somewhat branched. Clamp connections present at all tissues.

More micro-drawings

The description is based on one Swedish and five Norwegian collections.

Microphotos of cheilocystidia 1

Microphotos of cheilocystidia 2

Microphotos of caulocystidia

Mycena cyanorrhiza is a member of sect. Viscipelles. The blue base of the stipe is a striking feature of M. cyanorrhiza, but also in M. amicta a blue base can be seen. There are several features separating the two species. In M. amicta the lamellar edge is not formed by a tough thread, 17 - 25 lamellae are reaching the stipe, the spores are broader, and the cheilocystidia are completely different. M. amicta usually is a larger species, with darker colours, and with a conspicuously white-pubescent stipe. The base of the stipe usually is somewhat blue-green, but sometimes it can be entirely blue.

Occasionally the blue colour apparently can be absent in Mycena cyanorrhiza. One Norwegian collection showed very little blue colour, and in several specimens it seemed to be completely absent, and in such cases the gelatinous gill edge thread eould be one of the better characters to use.

In the literature Mycena pachyderma has been associated with M. cyanorrhiza. The two species have several features in common, but M. pachyderma was described with a whitish stipe (not with a blue base), and the spores are subglobose, 6-9(-11) x 6-8 µm.

Robich (2003) proposed the new species M. pseudocyanorrhiza. It is supposed to have a darker pileus, longer stipe, broader spores, and hairs on the stipe with blue contents in fresh specimens. In addition the cheilocystidia were described as more globose and not embedded in a gelatinous layer. It has later been recorded from Spain (Pérez-de-Gregorio 2012). See also Perry et al. 2020.

Mycena subcaerulea (Peck) Sacc. has a blue or greenish stipe. It is an American species, so far not recorded in Europe. The spores are globose to subglobose, 6-8 µm broad.

Mycena cyanescens Vel. and M. cyanipes Godey are, according to Maas Geesteranus (1992: 32-33), doubtful taxa with nothing left of the type material and too brief descriptions to support any opinion of the identity.