Trooping Funnel

The Trooping Funnel is the giant of the Infundibulicybe group, a robust, long-stemmed mushroom that can reach a cap width of 20 cm and stand tall above the surrounding vegetation. As the English name suggests, it fruits gregariously, forming spectacular arcs, long lines and complete fairy rings that can be several metres across and persist for decades.

Its alternative name, Monk's Head, refers to the young stage: before the cap expands the fruit body has a domed, pale, tonsure-like top on a thick pale stalk. As it matures the cap flattens and then sinks into a broad funnel, but unlike most funnels it usually retains a low central boss or umbo in the middle of the depression, a very useful field mark.

The species was traditionally placed in Clitocybe and is still commonly listed as Clitocybe geotropa. Its epithet means turning towards the earth, a reference to the way the cap margin curves down and the mature funnel tips.

Cap

The cap is large, commonly 8-20 cm across and occasionally more, at first hemispherical with a strongly inrolled margin, later flat and finally broadly funnel-shaped. A distinct low umbo usually persists at the centre of the funnel. The surface is dry, matt to finely suede-like, and pale ochre-buff, cream-leather or pale tan, often paler and slightly frosted near the margin.

Gills

The gills are crowded, narrow and deeply decurrent, running a long way down the stipe. They are white to pale cream, sometimes with a faint buff flush in age, and are easily separated from the cap flesh.

Stipe

The stipe is tall and stout, 6-15 cm long and 2-4 cm thick, cylindrical and usually swollen towards a club-shaped base. It is pale cream to buff, finely fibrillose to slightly woolly, and firm with a solid, elastic interior. The base is bound into the soil by white mycelial cords. No ring and no volva are present.

Flesh and spore print

The flesh is thick, firm and white, unchanging when cut, with a pleasant sweetish or faintly almond-like smell. The spore print is white and the spores are smooth and elliptical.

The Trooping Funnel grows on the ground in grassy woodland rides, at woodland edges, along hedgerows, in scrub margins and in open clearings, favouring calcareous or neutral soils. It also appears in mature parkland and on grassy banks where leaf litter accumulates against vegetation.

It is a late-season species, fruiting from mid-autumn until the first hard frosts and often persisting as blackened remnants into winter. It is widespread across Europe and temperate Asia and is locally frequent, with individual rings recurring in the same place year after year.

This species is a saprotroph, decomposing leaf litter, grass thatch and fine woody debris. Its mycelium forms a thick perennial mat that advances outward from the point of establishment at a fairly constant rate each year, producing the classic fairy-ring pattern of fruit bodies at the leading edge.

Because the mycelium is dense and long-lived, established rings can be aged approximately from their diameter and known growth rate, and the grass inside the ring is often visibly different in colour and vigour from the surrounding sward due to changes in soil nutrients and water penetration behind the advancing front.

Infundibulicybe gibba, the Common Funnel, is a much smaller and thinner-fleshed species with a pinkish-tan cap and no persistent central umbo, growing scattered in woodland litter rather than in great troops. Leucopaxillus giganteus, the Giant Funnel, is comparable in size and also rings in grassland, but is whiter, has a shorter, thicker stipe relative to the cap, tougher flesh, and lacks the central boss.

Clitocybe nebularis is stout and similar in size but has a cloudy grey bloomed cap, gills that are only shortly decurrent, and a strong sweetish-mealy smell. Large Lepista species such as the Field Blewit differ in their lilac-tinged stipes and pale pink spore prints.