Stinking Earthfan Identification Guide

The First Impression

You are far more likely to smell Thelephora palmata than to see it. The setting is usually a conifer plantation or a mixed wood with spruce and pine, and the exact spot is usually compacted bare soil at a track edge, a mossy bank, or a needle carpet under close planted trees. On damp still air there is a rank, unmistakably putrid smell, and when you crouch to find the source there is a dark, upright, coral like tuft 3 to 7 cm tall that looks more like a scrap of charred wood or a leaf skeleton than a fungus. Nothing about it reads as a mushroom. There is no cap, no stem in the ordinary sense and no gills. What you have is a small branched shrub of tough, flattened fingers, chocolate to purplish brown, with conspicuously paler tips.

Overall Architecture

Work from the ground up. A short, narrow, tough common stalk is usually half buried in litter and often invisible until you scrape the needles away. From it the fruit body divides repeatedly, and the branches are the key: they are flattened rather than round in cross section, they broaden as they rise, and each one splits at the top into a group of narrow, blunt or slightly pointed lobes arranged in a plane. The effect is of a hand with spread fingers, or of a flattened antler, repeated several times over in one clump. Individual clumps are 2 to 6 cm wide, and neighbouring clumps often fuse at the base into a lumpy mass several centimetres across. The lobes are the paler parts, whitish, greyish or fawn when actively growing, so that a fresh colony looks frosted at the top and almost black at the bottom. As growth stops the pale tips darken and the whole thing becomes uniformly sombre.

The Fertile Surface

This is where the group differs most from a true coral fungus. The spore bearing layer is spread thinly over the outside of the branches, not concentrated on any special structure. Run a fingertip over a branch face and it feels slightly velvety and very finely uneven. Under a lens the surface is smooth to shallowly wrinkled or minutely warted, with no pores, no teeth, no gills and no ridges of any regular pattern. Only the actively extending tips are sterile, which is why they are paler. Nothing in the interior is fertile, so a cut branch shows only fibrous brown tissue.

Texture, Flesh and Base

Pick a branch and try to snap it. It will not break cleanly. The tissue is leathery and fibrous, and it tears in strings like wet cardboard or thin hide. That toughness is a strong genus level clue, because it rules out the brittle, chalk snapping corals. Cut a branch lengthwise and the flesh is dull brown throughout, of one colour, with no marbling and no colour change on exposure beyond a slight darkening as it wets. The base ends in a felty pad that glues itself to soil, needles and small twigs; teased apart it shows brown mycelial threads running out into the litter, and specimens often lift with a plug of needles attached. Dried material becomes stiff and dark and can persist for weeks, which is why you sometimes find last month's blackened clusters still standing.

Odour

The smell is the second half of the name and is genuinely diagnostic. Fresh, moist material gives off a strongly fetid, penetrating odour with a sour, sulphurous edge, easily detected a metre away on windless days. To sharpen it, cup a branch in your hands for a few seconds to warm it and then smell. Weathered or sun dried collections lose most of the smell, so absence of odour on an old specimen does not count against the identification, while a strong fetid smell from a dark branched terrestrial fungus counts strongly for it.

Getting a Spore Deposit

A classic cap down spore print is impossible here, but a deposit is still obtainable and worth having. Lay two or three branch tips horizontally on a glass slide or a strip of foil, cover them with a beaker to keep the air moist and leave them overnight. The result is sparse but usefully coloured, a warm purplish brown or dull chocolate. A second trick works in the field: look at the litter and at the lower branches directly beneath a mature cluster, where a fine brown dusting often accumulates. Under a microscope the spores clinch the genus, being angular and lobed in outline and covered in coarse warts or short spines, pale brown, and about 8 to 12 micrometres across. No coral fungus has spores like these.

Substrate, Partners and Season

Thelephora palmata grows out of soil, never out of wood, and it is ectomycorrhizal, sheathing the fine roots of conifers, especially spruce, pine and fir, and occasionally broadleaved trees in mixed stands. That partnership explains its habitat preferences: young or dense plantations, the mineral soil of banks and track sides where roots run close to the surface, and mossy needle beds. It tolerates poor, compacted and disturbed ground well and is often one of the few fungi fruiting on a bare forest road margin. The season is late summer to late autumn, with fruiting triggered by prolonged damp, and the fruit bodies are slow growing and long persisting rather than ephemeral. It is widespread across the temperate and boreal Northern Hemisphere and has travelled with planted conifers elsewhere.

Separating It from Look-alikes

• Thelephora terrestris shares the tough texture and dark brown colour but grows as flat, overlapping, fan shaped rosettes lying against the ground or clasping seedling stems, with a fringed pale margin. It is not erect and branched, and it lacks the strong fetid odour.
• Thelephora anthocephala and Thelephora penicillata are more slender and more finely divided, greyish to purplish brown with narrow whitish spine like tips, and their branches are less broadly flattened.
• Ramaria species are the commonest confusion. They are fleshy and brittle, snap cleanly, are usually much brighter in tone with ochre, tan, pinkish or yellow colours, have branches round in cross section and give an ochre yellow spore deposit.
• Clavulina cristata is white to greyish, brittle, and gives a white deposit.
• Tremellodendron and Sebacina species are whitish and rubbery gelatinous rather than leathery and brown.
• Anything growing directly from wood is not this species; Thelephora palmata is always attached to soil and litter.

A Working Sequence

On the ground the sequence is short: dark brown to purplish erect branched clusters on soil in conifer woodland; branches flattened and splitting into palmate lobes with paler tips; tough, fibrous, tearing rather than snapping; smooth velvety fertile surface on the outside of the branches; strong fetid odour when warmed; purplish brown deposit and warty, lobed spores under the lens.