Orange Mosscap Identification Guide

Where You Will Be Standing

Orange Mosscap turns up wherever moss forms a continuous carpet and stays damp. That means shaded lawns, churchyard turf, mossy banks, the tops of old walls, the mossy flanks of rotting logs, woodland rides and heathland hummocks. You spot a single orange pinhead standing a couple of centimetres above the moss, and once your eye has calibrated you realise there are thirty or forty of them scattered across a square metre.

The first impression is of a bright orange drawing pin on a thread. The scale is small but not vanishingly so: caps of three to ten millimetres on stalks of one and a half to four centimetres, tall enough to hold the cap clear of the moss surface. Bring a lens.

Reading the Cap

The cap shape is the first thing to fix. It is convex at first but develops a small sunken navel at the centre very early, and mature caps are distinctly umbilicate, sometimes almost funnel-shaped in old material. That depression is central to the identification and is easiest to see in profile against the light.

Colour is brightest in and around the navel, a clean orange to orange-yellow, fading outward to pale ochre-yellow and finally to buff at the rim with age and sun. The surface is dry to moist and never sticky, and under a lens it carries a fine frosted bloom. When wet the cap is translucent-striate, with the gill lines showing through as pale radiating stripes; when dry the striation fades. The margin is thin, often faintly scalloped.

Gills, Stipe and Base

Turn a cap over. The gills are white to cream, and that contrast against the orange cap is one of the strongest field marks on the species. They are strongly and long decurrent, running conspicuously down the stalk for several millimetres, subdistant to distant, comparatively thick, and often with low veins connecting them near the stem. Count them and you will usually find twelve to eighteen full-length gills with shorter ones between.

The stalk is half a millimetre to one and a half millimetres thick, cylindrical and equal, hollow, and flexible rather than brittle. It is pale orange-yellow, usually warmest just below the gills and paler downward. Its whole length is finely pruinose, and a lens shows that the frosting is a dense pile of projecting cells; this is worth checking because it holds across the genus.

At the base the stalk is bound into the moss by fine white mycelial threads, sometimes visible when you tease a plant out. There is no basal disc, no cup, no ring and no bulb.

Flesh and Colour Change

The flesh is minimal, pale yellowish, and does not change colour when cut or handled. There is no latex, no bruising reaction and no distinctive smell. A crushed cap leaves a faint orange stain on the fingers, but that is simply pigment. Any small orange agaric that reddens, blackens or exudes a coloured juice needs a different name.

Getting a Spore Print

Small caps mean you need several. Collect five or six mature specimens, trim the stalks, and set them gill-side-down on black card or a dark glass slide inside a covered box with a damp tissue for humidity. Leave them for four to eight hours or overnight. The deposit is white.

Microscopically the spores are small and unremarkable, about four to five and a half by two to two and a half micrometres, ellipsoid to cylindric, smooth, and inamyloid with no reaction in Melzer's iodine. What is remarkable is the cystidia. Rickenella species are studded with them, on the gill edges, the gill faces, the cap surface and the stalk surface alike, and a squash mount showing cystidia everywhere is effectively confirmation of the genus.

Substrate, Season and Ecology

This species is bryophilous: it lives with mosses, and its mycelium associates directly with moss rhizoids and stems rather than simply rotting general litter. Common host carpets include Brachythecium, Hypnum, Polytrichum and the mixed feather mosses of lawns and banks. If you find a candidate that is not actually growing out of moss, be suspicious of the identification.

It is one of the longest-fruiting small agarics in temperate regions, appearing from spring right through to hard frosts, and it is genuinely common and near-cosmopolitan. Fruitbodies are scattered to gregarious, never clustered from a common base.

Separating the Look-Alikes

Rickenella swartzii shares the size, shape, decurrent white gills and moss habitat, but has a violet-brown to almost blackish centre to the cap and a violet-tinged stalk apex. Look straight down at the navel: dark centre means swartzii, orange centre means fibula.

Orange Bonnet (Mycena acicula) is the closest colour match. It has a domed, never navelled cap, pale yellow gills that are adnate rather than decurrent, a yellow stalk, amyloid spores, and it grows on twigs, dead herbaceous stems and woody debris instead of moss carpets.

Loreleia postii and Loreleia marchantiae are orange with decurrent gills but are duller, more orange-brown, and are tied to burnt ground or to thalloid liverworts such as Marchantia. Their gills often carry an orange tint rather than being clean white.

Xeromphalina campanella grows in dense swarms on rotting conifer wood, has a rusty orange-brown cap, yellowish decurrent gills, and a tough dark red-brown stalk with a conspicuous tuft of coarse hairs at the base.

Chrysomphalina and Haasiella species are larger, with orange or yellow gills rather than white, and grow on wood or rich humus.

Small Galerina and Cortinarius species in moss can be a similar size but have brown spore prints and brown gills at maturity.

Field sequence: navel-centred orange cap, white strongly decurrent gills, pruinose orange-yellow stalk, and moss underneath. Four checks, all doable with a lens on your knees.