Dog Stinkhorn
Mutinus caninus
Also called dog's stinkhorn, lesser stinkhorn, small stinkhorn
A slim, delicate stinkhorn whose tapering pale stalk ends in an orange tip smeared with dark spore slime. It has no separate cap, which distinguishes it from the larger Phallus species.
Overview
Mutinus caninus is the small, slender cousin of the familiar large stinkhorns. Rather than carrying a distinct bell-shaped head, its fruiting body simply tapers to a narrow orange or orange-red apex on which the dark gleba is smeared directly. The result is a much slighter, more delicate structure, typically only finger-thick at most, that emerges from a small whitish egg in leaf litter.
The genus Mutinus sits in the Phallaceae alongside Phallus, sharing the egg stage, the hollow spongy stalk, the sac-like volva at the base and the reliance on insects for spore transport. The key structural difference is the absence of a free-margined cap: in Mutinus the spore-bearing surface is continuous with the stalk.
It is a common woodland fungus of Europe and also occurs in North America, fruiting in small groups among leaf litter, on rotting wood and in mulched garden beds. Its odour is much weaker than that of the large stinkhorns, so it is usually found by sight rather than by nose.
How to identify it
Egg stage
A small, ovoid whitish to pale ochre egg 1.5–3 cm across, lying in the litter and attached by fine white rhizomorph cords. Cut lengthwise it shows gelatinous layers around the folded stalk with a narrow dark gleba band at the top.
Stalk
Slender and cylindrical, 6–12 cm tall and only 0.7–1.5 cm thick, hollow, spongy and pitted-chambered, tapering gently towards the apex and often slightly curved. The lower part is white to pale cream or pale yellowish, grading upwards to yellow-orange and then orange to orange-red at the tip. The base sits in a small, loose, whitish volva.
Fertile tip
There is no separate cap. The upper 1.5–3 cm of the stalk is the fertile zone: it is bright orange to orange-red and, when fresh, covered in dark olive to olive-brown sticky gleba. Once insects have removed the slime the bare orange tip is exposed, sometimes with a slightly roughened or granular surface.
Flesh & spores
The wall is thin, spongy and fragile, collapsing readily. Spores are borne in the gleba slime and are not shed as a dry print; they are small, smooth and ellipsoid, the mass reading olive-brown.
Where and when it grows
The Dog Stinkhorn fruits in shaded, damp places on decaying organic matter: deciduous and mixed woodland leaf litter, rotting stumps, buried wood, sawdust, wood chips and mulched garden beds. It frequently grows in small troops of several fruiting bodies, with eggs at various stages nearby.
It is widespread and common in Britain and mainland Europe and is also recorded from North America and other temperate regions, though some North American reports may involve closely related species. Fruiting runs from summer through late autumn, most abundantly after periods of warm, wet weather. Individual fruiting bodies are short-lived, expanding in hours and collapsing within a day or two.
Ecological role
Mutinus caninus is a saprotroph, its mycelium decomposing leaf litter, buried twigs, rotting stumps and wood chips. Fine white cords link the eggs to the colonised substrate, and expansion of the stalk depends on rapidly drawing water into pre-formed spongy chambers rather than on new growth, so a fruiting body can go from egg to full height in a matter of hours.
Dispersal is by insects, chiefly flies, which are drawn to the odour of the ripening gleba. The smell is markedly fainter than that of Phallus impudicus, and the fungus appears to rely partly on the bright orange tip as a visual signal. Visiting insects feed on the slime, become dusted with spores and transport them to new litter and wood debris, where the cycle begins again.
Similar species
Mutinus elegans is larger and more robust, with a longer, more gradually tapering fertile zone and a deeper orange to pinkish-red colour running well down the stalk. Mutinus ravenelii has a distinctly pink to rose-red stalk with a more abruptly demarcated, swollen red head. Careful comparison of colour distribution and the length and shape of the fertile tip separates the three.
Phallus impudicus, P. hadriani and P. ravenelii are all far stouter, with a thick white stalk and a distinct bell- or thimble-shaped cap that is free at its lower margin — a structure Mutinus never has. Young unopened eggs of Mutinus can be mistaken for small puffballs or for Phallus eggs, but they are smaller than the latter, and a lengthwise cut reveals the slender folded stalk with its narrow gleba band.