Glistening Ink-Cap

Description

The Glistening Ink-Cap has a small cap, usually 1–5 cm, yellow-brown or tawny, bell-shaped, with distinct grooves running from the margin almost to the centre. Young fruiting bodies are covered with fine, whitish, glistening granules that resemble crumbs of mica and are easily washed off by rain. The stem is white, brittle and hollow inside, 3–10 cm long. With age the gills darken from white through brown to black.

It grows from May to November, usually in dense clusters on stumps and roots of broadleaved trees, also on buried wood, in gardens, parks and along roads. In Poland it is common. After many days of rain, or a few hours after picking, the gills deliquesce into a black, ink-like liquid.

It is most easily confused with other Coprinellus species, especially Coprinellus truncorum, from which it is practically impossible to distinguish in the field, and with the common ink cap, which causes unpleasant symptoms when eaten with alcohol. If you are not sure of the species, do not pick it or eat it.

Identification features

Cap

Ovoid to cylindrical when young, 1–2.5 cm in diameter, then bell-shaped, sometimes with a broad umbo, finally spread out and slightly convex, 0.8–5 cm in diameter and a few centimetres high. Margin pleated, grooved almost to the centre (the grooves correspond to the positions of the longer gills), in older fruiting bodies split radially and slightly turned up. Colour yellow-brown to tawny, often with a darker centre, paler (cream) towards the margin; the cap is hygrophanous. When young it is covered with whitish, glistening granules – remnants of the universal veil, made up of colourless, smooth, spherical cells about 25–65 µm in diameter (most often 40–50 µm). The granules are easily washed off by rain, so older specimens are often smooth. In wet weather the cap deliquesces.

Hymenophore (underside of the cap)

Gills crowded, narrowly attached to the stem, white when young, then dark brown, finally black; the edges remain white for a long time. The expansion of the cap splits the gills along the median plane and tears the margin into rays. Autolysis (deliquescence) begins with the lower part of the gills, before the upper part has turned completely black. In wet weather the gills deliquesce into a black liquid saturated with spores; the process can begin as early as an hour after picking.

Stem

Length 3–10 cm, thickness 2–5 mm, more or less equal in thickness along its whole length, cylindrical, brittle, hollow inside. Colour white, may fade from the base to dirty cream. In young specimens finely dusted with a whitish, velvety bloom, which disappears with time, leaving the stem more or less smooth and shiny. At the base there is sometimes a rudimentary ring – another remnant of the universal veil.

Flesh

Thin, brittle, white in the stem, brownish in the cap. Smell and taste not distinctive. The flesh should not be tasted for identification.

Spore print and spores

Spore print dark brown to brownish-black. Spores 7–11 × 4–7 µm (descriptions give different ranges), reddish-brown to black, smooth, almond-shaped or spindle-shaped in side view, ovoid to mitre-shaped in front view, lens-shaped, with a central, truncate germ pore.

Habitat and distribution

Ecology. A saprotroph growing on dead organic matter: on stumps, logs and roots of broadleaved trees and on buried wood. It prefers bark, especially the secondary phloem, rather than the wood itself; in the succession of wood-decay fungi it appears late, on wood that is already softened. It may also live as an endophyte in the tissues of healthy trees. Often found in disturbed places: along roads and paths, in gardens, on building sites, at the edges of car parks; it also occurs indoors in damp rooms on rotting wood. Fruiting bodies usually grow in dense clusters, less often singly; the mycelium fruits repeatedly in the same place.

Distribution. A cosmopolitan species: Europe (including Turkey), North America (as far as Alaska), South America, Asia, Africa, Australia, New Zealand, Hawaii. Common in Poland, in forests, gardens and parks. It is not legally protected in Poland.

Fruiting. In Poland from May to November; in Europe from May to December. More frequent in spring and autumn, in periods of higher humidity. A single fruiting body matures on average within 5–7 days.

What can it be confused with?

• Coprinellus truncorum (Polish: czernidłaczek pniowy) — Also covered with glistening granules; practically indistinguishable in the field, the microscope decides (spores ellipsoid with a rounded pore, rather than mitre-shaped with a truncate one). C. micaceus is said to be browner in the centre of the cap and to grow in clusters more often.
• Coprinellus disseminatus (fairy inkcap) — Smaller; the cap has no glistening granules but fine hairs or small scales; it grows in very large numbers on rotting wood, the gills turn black but do not deliquesce.
• Coprinellus angulatus (Polish: czernidłaczek kanciastozarodnikowy) — Difficult to tell apart; cap surface matt, gill edges are not white; reliable identification requires a microscope.
• Coprinellus bisporus — Almost identical, but without yellowish granules on the cap and with two-spored basidia.
• Coprinellus xanthothrix (Polish: czernidłaczek żółtołuseczkowy) — Yellow, felted stem base.
• Coprinopsis atramentaria (common ink cap) — Larger, grey, without glistening granules on the cap; grows in dense clusters on stumps or buried wood. Contains coprine and causes unpleasant symptoms when eaten with alcohol.
• Psathyrella candolleana (pale brittlestem) — The gills also darken, but the cap has no radial grooves.
• Mycena inclinata (clustered bonnet) — Similar in colour and grows in groups on stumps, but has white gills and a smaller cap.

Never rely on a single feature. If you are not sure — do not pick it; show the mushroom to a qualified mushroom expert.

Interesting facts

• It was illustrated with a woodcut as early as 1601 in Carolus Clusius's work Rariorum plantarum historia; Clusius wrongly considered it poisonous.
• Scientifically described by Bulliard in 1786 as Agaricus micaceus; the epithet alludes to the Latin mica ("grain"), and the glitter of the granules results from the reflection and refraction of light in the spherical cells.
• It is a classic subject of cytological research: it has synchronous meiosis and clearly visible chromosomes (n = 12), and the first successful laboratory culture from spores was described in 1914 by Michael Levine.
• It can fruit repeatedly in the same place: from a single elm stump a total of about 17 kg of fresh mushrooms was collected in 10 successive flushes.