Conical Brittlestem Identification Guide

First Impression and Setting

You tend to meet this species on the ground in rich, disturbed, nitrogen-fed places rather than deep in undisturbed woodland. Path edges through parkland, nettle beds, hedge bottoms, garden borders mulched with woodchip, the spoil around a rotted-out stump and roadside verges are all typical. It fruits scattered or in loose groups, rarely in tight tufts.

The impression at ten paces is of something improbably tall and thin. A very slender, gleaming white stem, sometimes a hand's length or more, rises out of the litter and carries a small dark cap that has stayed conical. The cap looks too small for the stem, and the whole thing sways in any breeze. On a wet morning the caps are dark date-brown and glossy; by afternoon they have paled to a dull ochre-grey from the top downward, and the fungus looks like a different organism.

Reading the Cap

Shape. The defining character is that the cap does not open out. It begins narrowly conical or bullet-shaped, and at most becomes broadly conical or bell-shaped with a slightly flared rim in age. It never flattens into a plane, and it never turns up at the edges. Expect roughly 1.5 to 4 cm across and often nearly as tall as it is wide, so the outline is a cone rather than a dome.

Hygrophanous colour. Moist caps are a rich date-brown, chestnut or dark reddish brown, sometimes with a slightly darker centre. Drying begins at the apex and works down, leaving a pale clay, buff or greyish-ochre cap with a darker ring lingering low on the flanks. A collection sitting in a basket for an hour will pale visibly, so record colour when you pick.

Margin and striation. When moist, the margin is finely lined or striate, the lines corresponding to the gills beneath, and the striations may run a third or more of the way up. The cap does not, however, become deeply and radially pleated like a folded fan.

Surface hairs. This is the character worth carrying a strong lens for. The cap cuticle bears long, thick-walled, pointed hairs that can reach a millimetre or more. At 10x to 20x, viewed against the light along the profile of the cap and especially near the disc, they show as a fine bristly fringe standing off the surface, easier to see on a dry cap than a wet one. A scrape from the cap surface shows them under a microscope as long, tapering setae, and they are the classic confirmation of this species.

Flesh. Extremely thin, watery brown when moist, pallid when dry, with no colour change on cutting.

Reading the Gills

Attachment. Free to narrowly adnexed, often with a very narrow gap between gill and stem.

Spacing. Crowded, narrow, with several tiers of shorter gills.

Colour sequence. Pale grey-brown or clay-buff at first, then darkening rapidly through grey-brown to a deep blackish-brown or nearly black as the spores mature. The change happens fast, often within a day.

Behaviour at maturity. Watch this carefully, because it separates the species from true inkcaps. The gills darken and the cap eventually withers, shrivels and collapses, but it does not dissolve into a running black liquid. There may be a slight weeping along the gill edge in very wet weather, but no genuine autodigestion into ink.

The Stipe, Base and Handling

Proportions. The stipe is the other headline feature. It is 8 to 15 cm long, sometimes reaching 20, and only 2 to 4 mm thick, giving an extraordinarily attenuated look. It is straight or slightly flexuous, and often longer than seems possible for the cap it carries.

Colour and surface. White to very pale cream, smooth, silky and distinctly shining, finely pruinose toward the apex under a lens.

Interior and the snap. Hollow throughout. Bend it and it snaps cleanly rather than tearing, which is the brittlestem character the common name records. The break is sharp and the fracture face is clean.

Base. Slightly swollen or bulbous, sometimes with a small pad of white mycelium binding soil, wood fragments and buried plant debris. There is no volva, no ring, and no ring zone anywhere on the stipe.

Taking and Reading the Spore Print

The print here is both easy and diagnostic, because the spores are heavy and abundant.

Sever the stipe, place the cap gill-side down on white paper, cover it to keep humidity and stop draughts, and leave it. Mature caps drop very quickly, often producing a usable deposit within an hour, and an over-mature cap left overnight may deposit so heavily that the paper looks painted.

The colour is a deep, dark blackish-brown to sooty black, occasionally with a faint purplish note when thin. Smear a little with a fingertip to judge it against the white background.

Under a microscope the spores are unusually large: roughly 13 to 18 micrometres long by 7 to 9.5 wide, smooth, ellipsoid to slightly almond-shaped, very dark brown in water, and each carrying a distinct central germ pore visible as a pale spot at one end. Spore size alone will separate this species from most of the small-spored brittlestems that grow alongside it, and it is the single most decisive character available.

Substrate and Season

This is a decomposer of buried woody and herbaceous debris rather than a wood-tufting species in the usual sense. Expect it on rich humus, leaf mould, woodchip mulch, decayed roots, compost-influenced soil and heavily manured verges, in parks, gardens, hedgerows, nettle patches and along woodland tracks.

Fruiting runs from late spring through autumn in temperate regions, with the heaviest flushes in summer and early autumn after rain. The fruitbodies are short-lived, often collapsing within a day or two.

Separating the Look-Alikes on Morphology Alone

Typical Psathyrella species are the main confusion, since they share the brittle white stipe, the hygrophanous cap and the dark print. Separate them on cap shape and stipe proportions first: most have broadly convex to flat caps on stipes well under 10 cm and much stouter relative to the cap. Then use spore size, around 5 to 9 micrometres in most of them against 13 to 18 here.

Pleated inkcaps of the same genus (Parasola plicatilis and relatives) are much smaller, with caps that expand flat and become deeply and radially grooved like a folded parasol, with widely spaced gills attached to a small collar around the stipe apex. They also last only hours. The persistently conical, ungrooved cap here is a clear separation.

Parasola auricoma is closer, because it too has thick-walled hairs on the cap, but its cap expands and becomes distinctly pleated, and it is smaller and more russet in tone.

Coprinellus and Coprinopsis species may be similar in stature but their gills genuinely deliquesce into black liquid, and most carry a conspicuous veil in the form of glistening granules, mealy powder or shaggy scales on the cap. This species has a bald cap and no veil.

Panaeolus species favour dung and grassland, have caps that stay convex and rather leathery, and show characteristically mottled gill faces where uneven spore ripening produces a blotchy pattern. Their stipes are tough rather than brittle.

Mycena species with tall thin stipes are separated instantly by a white spore print and pale gills.