Blue Pinkgill Identification Guide

The setting and the first impression

There is no gentle introduction to the Blue Pinkgill. You are walking a damp track through native forest, the light is low and green, and something on the bank beside you is an impossible shade of indigo. Nothing else on the forest floor is that colour. The fruit body is small, a cap of 2-4 cm on a slender stem 3-6 cm tall, but the saturation of the blue carries across several metres of leaf litter. Typical settings are moist, shaded broadleaf and podocarp forest, the mossy banks of tracks and streams, the litter beneath tree ferns, and the deep humus around beech and rimu. They come up singly or in small scattered groups, usually where the litter is thick, permanently damp and undisturbed, and they are commonest through the wetter months of autumn and winter.

Reading the cap

Look at the profile before you touch it. Young caps are conical to bell-shaped, then expand to broadly convex, and most retain a distinct pointed or nipple-like umbo at the centre, so the mature outline is a low dome with a raised peak. The colour when fresh is a deep indigo to greenish-blue, strongest at the umbo and slightly paler towards the margin; as the fruit body ages and dries the blue mutes towards a duller slate or takes on olive and greenish tones, and old caps can bleach to a washed-out grey-blue. The surface is dry and finely fibrillose, with fine radiating fibrils running from the umbo to the edge that catch the light and give a silky sheen; the very centre often looks minutely scaly under a lens. In wet weather the margin becomes faintly translucent and the lines of the gills show through as short radial striations, which fade as the cap dries.

Reading the gills

Turn it over carefully, because the underside is where the identification is made rather than confirmed by colour alone. The gills are moderately spaced, fairly broad and ventricose, and attached to the stem with a notch or narrow adnexed attachment; they are not decurrent. Their colour changes dramatically with age and this sequence is the key character. Young gills are blue to blue-grey, matching the cap. As the spores ripen the gill faces flush salmon to dull pink, and by maturity you are looking at pink gills beneath a blue cap, a contrast that is diagnostic and rather startling. The gill edges are usually concolorous with the faces rather than dark-fringed. Look at several caps of different ages in the same group, because seeing that blue-to-pink progression across the group is far more convincing than any single specimen.

Stem, base and flesh

The stem is 3-6 cm long, 3-6 mm thick, more or less equal or slightly widening downwards, and often a little curved or twisted where it emerges from the litter. It is the same blue as the cap or a shade brighter, longitudinally fibrillose so that fine paler fibres run along its length, and it is hollow or narrowly stuffed rather than solid. There is no ring, no veil and no cobwebby cortina, which matters when you come to eliminate look-alikes. Lift the whole fruit body rather than snapping the stem: the base sits in leaf litter and carries a small tuft of pale to bluish mycelium binding fragments of humus, twig and moss. The flesh is thin, fragile, and bluish in the cap and stem cortex, and it does not change colour appreciably when cut. Handle gently, because the fruit body bruises and the stem breaks easily.

Taking a spore print

Because the blue colour is so arresting, people often skip the spore print, and that is exactly where identifications go wrong. Cut the stem flush against the gills, place the cap gills-down on white paper, cover it with a cup or bowl to keep the humidity up, and leave it for two to four hours or overnight. The deposit is pink to salmon-pink, sometimes reading as brownish-pink where thick. That single result is what places the fungus in Entoloma and eliminates the two most plausible confusions in one step. Under a microscope, the spores are the family's signature: angular in outline with several straight facets, heterodiametric, roughly 10-13 by 7-9 micrometres, looking like small irregular crystals rather than smooth ellipsoids.

Substrate, season and ecology

The Blue Pinkgill is a terrestrial species of forest floors, growing directly from leaf litter and humus rather than from wood, though it will sometimes appear on very rotted, litter-buried debris. Its stronghold is the moist native forest of New Zealand, where it is one of the country's best-known fungi, and closely comparable blue pinkgills have been reported from other parts of the Southern Hemisphere and from parts of Asia. It favours permanently damp, shaded sites with deep undisturbed litter, and it is frequently associated with mixed podocarp and southern beech forest and with the moist ground beneath tree ferns. Fruiting concentrates in the cooler, wetter half of the year, chiefly autumn through winter. Its trophic strategy is debated: many Entoloma species are litter decayers, while some form associations with tree roots, and the genus contains both strategies.

Separating it from look-alikes on morphology alone

Blue is rare enough on a forest floor that the candidate list is short, but the ones that exist are genuinely similar.

Entoloma virescens is the nearest relative in appearance and shares the pink spore print and angular spores. Look at the cap surface and profile: E. virescens typically has a more sharply pointed, drawn-out umbo and a cap that is smoother and often slightly greasy or viscid when moist, whereas E. hochstetteri is dry and distinctly fibrillose with a lower, broader umbo. The blue of E. virescens frequently carries a stronger green cast.

Cortinarius rotundisporus and other blue Cortinarius species can be startlingly blue in the cap, but they are stouter, have a cobwebby cortina between the cap margin and stem when young, usually retain rusty fibres on the upper stem where spores have caught in the veil, and produce a rust-brown spore print. Any rusty tone on the stem rules out a pinkgill immediately.

Blue Mycena and small blue Hygrocybe or Gliophorus species are separated by the spore print, which is white in all of them, and by texture: waxcaps have thick, waxy, widely spaced, usually decurrent gills and a distinctly greasy or slimy cap, while Mycena are far more fragile with a translucent-striate cap and a wiry stem.

Entoloma serrulatum and related small blue grassland pinkgills share the pink print but are darker, blue-black rather than indigo, grow in open short turf rather than forest litter, and show a dark, finely toothed gill edge under a lens.

Field checklist

Deep forest litter, cap 2-4 cm, intense indigo to blue-green with a fibrillose surface and a small pointed umbo, gills blue then salmon-pink and notched at the stem, stem blue and fibrillose with no ring or cortina, pink spore print, angular spores. Colour draws you in, but it is the pink print under a blue cap that closes the identification.