Bleeding Tooth Fungus

Hydnellum peckii is one of the stipitate hydnoid fungi, a group that carries its spore-producing surface on downward-pointing spines rather than gills or pores. It sits in the family Bankeraceae alongside Hydnellum, Phellodon, Sarcodon and Bankera, all of which produce tough, corky, often zoned fruiting bodies that grow slowly out of the forest floor and persist for weeks. Within that group Hydnellum is distinguished by brown spores and fibrous, frequently duplex flesh.

What makes this species famous is guttation. While a fruit body is still actively expanding, it pushes out droplets of pigmented liquid that bead across the pale, felted upper surface in startling scarlet or carmine beads. The colour comes from pigments produced in the flesh, and the effect is strongest in humid weather on young specimens. Once growth slows the droplets stop, the liquid dries to rusty stains, and the whole fungus darkens to a dull brown, at which point it is far harder to name at a glance.

The genus as a whole is closely tied to old, undisturbed conifer stands with thin humus, and Hydnellum peckii is often treated in Europe as an indicator of long continuity in such woodland. Its fruit bodies grow around whatever they meet, engulfing needles, twigs and grass blades, so a mature colony can look like a lumpy pale crust studded with vegetation.

Fruiting body

3-10 cm across and often wider where several bodies fuse. Young caps are white to pinkish-cream, irregularly domed and covered in a fine felty or velvety layer that becomes pitted, scurfy and finally scaly. With age the surface bruises and dries to dull brown, blackish-brown at the centre, keeping a paler growing rim. Individual bodies frequently coalesce laterally into broad, distorted sheets.

Spines

The underside carries crowded, slender spines 1-6 mm long, running down onto the top of the stalk. They are white to pale pink when young, ageing to grey-brown and then dark brown as the spores mature. Their tips are fine and even, giving the underside a soft, dense, plush texture.

Stipe

Short, thick, often off-centre and partly buried, 1-5 cm tall and up to 3 cm thick, coloured like the cap or darker brown, felted, and frequently swollen or root-like where it grips the litter layer.

Flesh and spore print

The flesh is tough, fibrous and corky, pale pinkish-buff to brown, and typically shows a faint zoned or two-layered structure when sliced vertically. Fresh specimens exude the characteristic red liquid from the upper surface. The spore print is brown; the spores themselves are warted and irregular under magnification.

This is a fungus of coniferous woodland, appearing on mossy, thin, acidic and often sandy soils under spruce, pine and fir. It favours mature stands with a shallow needle layer, along track edges, on banks and in the moss beneath closed canopy, and it tends to return to the same patch year after year because the underlying mycelium is long-lived.

Fruiting runs from mid or late summer through autumn, with the red droplets appearing during the earliest, wettest phase of expansion. The species is widespread across the boreal and montane conifer belt of Europe and North America, being frequent in Scandinavia, upland Britain, central Europe and the Pacific Northwest, with scattered records from parts of Asia including Korea and Iran.

Hydnellum peckii is ectomycorrhizal, forming sheathing root associations with conifers and exchanging soil-derived nutrients for sugars from the tree. Because the partnership depends on undisturbed root systems and low-nutrient soil, colonies establish slowly and are easily lost when a site is fertilised, ploughed or heavily shaded by dense litter accumulation. Populations of this and related Bankeraceae have declined across parts of lowland Europe, and the group is widely used as a signal of ecological continuity in conifer forest.

The fruit bodies themselves are unusually persistent for an agaric-sized fungus, standing for many weeks and releasing spores gradually from the spines as they darken. Their habit of growing around obstacles means they physically incorporate litter, mosses and small plants into the developing tissue, a growth pattern shared with several other members of the genus.

Hydnellum ferrugineum is the closest match and also exudes reddish droplets, but its fruit bodies are usually flatter, more rusty-brown overall, the flesh is more distinctly two-layered with a soft upper zone above a firm lower zone, and it favours dry sandy pine soil. Hydnellum aurantiacum shares the corky texture and brown spines but has a strong orange stipe and orange flesh, and never bleeds red. Hydnellum concrescens is thinner, strongly concentrically zoned in reddish-brown bands, with a flattened, often funnel-shaped cap and no droplets.

Phellodon species such as Phellodon tomentosus and Phellodon niger are superficially similar toothed fungi of the same habitats, but they have a white spore print, whitish to grey spines, and tough, dark, two-layered flesh; Phellodon niger is blue-black rather than cream. Sarcodon species are altogether larger and coarser, with a scaly brown cap and no bleeding surface.