Grey Coral Identification Guide

What You Notice First

Grey Coral rarely announces itself with colour. You are usually walking a damp woodland track in early autumn, eyes down on a mossy bank or a needle bed, when a small dull shrub resolves out of the litter: a clump 3 to 8 cm tall and about as wide, densely branched, and coloured the flat grey of wood ash or old pewter. Fresh material can carry a faint violaceous or lilac wash, especially near the branch tips, and very young fruit bodies can look almost pale sand-grey before the tone deepens. The surface is matt rather than shiny, and the whole thing looks slightly dusty even when wet.

The habit is the second impression. Individual fruit bodies rise from a short common trunk at ground level and divide again and again, so the outline is bushy and rounded rather than open and antler-like. Several fruit bodies often fuse into a low ridge or a broken row along a bank, and it is common to find them among moss where the bases are hidden.

Reading the Branches

Work from the base upward. The trunk is short, sometimes barely 1 cm before the first fork, greyish and often paler than the branches. Branching is repeated and irregular, giving three, four or more orders of division. Individual branches are round in cross section when young; older ones flatten, groove longitudinally, and occasionally develop a shallow channel down one face.

Now look hard at the tips, because this is where Clavulina identifications are won or lost. In Grey Coral the branch apices are blunt, rounded or bluntly two- or three-pronged. They are not divided into a crown of fine, sharp, comb-like teeth. Bring a hand lens right up to a tip in good light. A slightly ragged apex is normal in old material, but true crested tips look like frost on a twig and belong to a different species.

The Spore-Bearing Surface

Corals have no gills, pores or teeth. The fertile layer is amphigenous, meaning it coats the outside of the branches all over, including the sides and the spaces between forks. It is smooth to the eye and to the touch, without wrinkles, ridges or granules. Only the lowest part of the trunk, where it meets soil, is sterile.

Because of this, damage shows differently from an agaric. Rubbing a branch may leave a slightly darker grey smear, and handled specimens brown a little at the pressure points, but there is no sudden colour flush, no latex, and no bruising to blue, red or black. Snap a branch: it breaks cleanly and rather brittlely, not with the rubbery stretch of a jelly fungus. The internal flesh is white to very pale grey and stays that colour on exposure to air, which is worth checking with a fresh cut in the field.

Taking a Spore Print

A coral will drop spores, but you have to give it a fair chance. Cut a branch cluster free with a little of the trunk, stand or lay it on a piece of black card or a sheet of glass over black paper, cover it with a bowl or beaker to hold humidity, and leave it four to twelve hours somewhere cool. The deposit is white and often scanty, which is exactly why a dark background matters; on white paper you may convince yourself nothing fell.

Under a microscope the spores are smooth, broadly ellipsoid to nearly spherical, roughly 7 to 11 by 6.5 to 9 micrometres, and hyaline. The basidia are the giveaway for the genus: typically two-spored, with long, slender, curved sterigmata that look like tuning forks. Four-spored basidia and an ochre or yellow-brown deposit point away from Clavulina altogether.

Substrate and Season

Grey Coral is mycorrhizal, so it grows from soil and never from wood. Expect it under both broadleaves and conifers: beech and oak on humus-rich banks, spruce and pine on old needle beds, and often along the mossy shoulders of forest tracks where the litter is thin and damp. It fruits from late summer through to the first hard frosts, peaking in the middle of autumn, and it is gregarious, so a single find usually means a scattered troop within a few metres.

One ecological detail explains a lot of confusing collections. A small ascomycete parasite, Helminthosphaeria clavularum, colonises Clavulina fruit bodies and coats them with a dark slate to blackish, faintly velvety layer that creeps up from the base. Infected white corals turn grey and get recorded as Grey Coral by mistake. If your grey coral has a sooty, matt, almost furred texture where the grey is deepest, and paler tissue survives elsewhere, suspect a parasitised specimen and check the branch tips again.

Separating the Look-Alikes

Crested Coral, Clavulina coralloides. White to cream, with tips finely divided into sharp, comb-like crests. Parasitised material goes grey and mimics Grey Coral closely, so ignore colour and read the apices with a lens.

Wrinkled Coral, Clavulina rugosa. Whitish to greyish, but sparsely branched, with a few thick, irregular, wrinkled and often contorted branches rather than a dense bush. The surface is uneven and rugose rather than smooth.

Ramaria species. Usually fleshier, with a fat basal stem, more numerous branches held in a tighter upright architecture, and colours running to buff, tan, ochre, yellow or pink-tipped. Decisively, the spore deposit is yellowish to ochre-brown and the spores are ornamented, not smooth.

Ramaria stricta. Grows on buried or exposed wood, has strictly parallel upright branches, ochre to pale tan colouring and bruises wine-brown where handled.

Thelephora palmata and Thelephora terrestris. Tough and leathery rather than brittle, with flattened, spatulate, fan-shaped divisions and paler tips, a distinctly unpleasant odour, and a brown deposit of warted spores.

Clavaria and Clavulinopsis species. Simple, unbranched clubs or spindles in tufts. If nothing forks, you are not in Clavulina.

Sebacina incrustans. Encrusts stems, litter and grass bases in lumpy pale grey sheets and only crudely imitates branching; it lacks the free, repeatedly forked, ash-grey bush of Grey Coral.

A Quick Field Checklist

Growing from soil, not wood. Densely and repeatedly branched from a short common trunk. Uniform ash-grey, sometimes lilac-tinted. Branch tips blunt, never finely crested. Surface smooth and fertile all over. Flesh white, brittle, unchanging. Spore deposit white, spores smooth and nearly round, basidia two-spored. Match all of those and the grey coral in front of you is very likely Clavulina cinerea.