Horn of Plenty

The Horn of Plenty is one of the most peculiar-looking fungi of temperate woodland: a hollow, thin-walled funnel that flares open at the top like a small trumpet, coloured in sooty greys and browns that make it almost invisible against dead leaves. There is no separate cap and stalk — the whole fruit body is a single continuous tube, open right down to the base.

It belongs to Craterellus, the sister genus to Cantharellus within the Cantharellaceae. Where chanterelles fold their fertile surface into blunt ridges, this species reduces it almost to nothing: the outer face of the funnel is smooth to shallowly wrinkled and veined, and it is this surface that produces the spores.

Despite being common where it occurs, it has a reputation for being hard to spot. Fruit bodies grow in dense, overlapping troops of dozens, and once a first specimen is seen, whole colonies often resolve out of the litter around it.

Fruit body

The fruit body is 3–12 cm tall and 2–8 cm wide at the mouth, shaped like a deep funnel or trumpet, hollow all the way to the base with no distinction between cap and stalk. The margin is thin, wavy, lobed and often split, inrolled at first and later flaring and recurved.

Inner surface

The inside of the funnel is dark grey-brown, sooty brown or nearly black, and is roughened with small scales, fibrils or a scurfy texture. It becomes paler and greyer as the fruit body dries.

Outer (fertile) surface

The outside is the spore-bearing surface. It is smooth to shallowly wrinkled with low, blunt, irregular veins that fork and anastomose, never forming distinct gills or ridges. It is ash-grey to grey-brown, distinctly paler than the interior, and often carries a whitish bloom from the deposited spores.

Flesh & spore print

The flesh is very thin, membranous, pliant, grey-brown, and does not change colour when cut. The odour is faintly fruity to slightly aromatic. The spore print is white to pale cream.

Fruit bodies push up through leaf litter and moss on soil in broadleaf and mixed woodland, most often with beech and oak, sometimes with hazel, hornbeam or lime. It favours damp, shaded ground with a deep litter layer, and frequently grows on mossy slopes, in hollows and along stream banks on calcareous soils.

The season runs from late summer to late autumn. The species is widespread across Europe and North America, and closely related black trumpets occur in Asia, with the whole group tied to temperate broadleaf forest.

The Horn of Plenty is ectomycorrhizal, forming a fungal sheath around the fine roots of beech, oak and other broadleaf trees. Its mycelium threads through the litter layer, capturing water and mineral nutrients that are passed to the host in exchange for photosynthetic sugars.

Because it is bound to living trees, it cannot be cultivated apart from a host, and its dense colonies indicate an established mycorrhizal network beneath the litter. Those networks are long-lived, so productive patches reappear in the same hollows year after year as long as the woodland is undisturbed.

Craterellus fallax, the eastern North American black trumpet, is nearly identical in shape and colour and is separated chiefly by its ochre to salmon-buff spore print rather than a white one. Craterellus cinereus is similar in colour but has clearly developed blunt, gill-like folds on the outer surface instead of a near-smooth face. Craterellus tubaeformis shares the hollow funnel form but is yellow-brown with a bright yellow stalk and prominent forking ridges.

Pseudocraterellus undulatus is smaller and greyer with a more strongly wrinkled outer surface and a less deeply hollow, more solid base, while the various Urnula cup fungi are stiffer, cup-shaped rather than trumpet-shaped, and not hollow to the base.