Blushing Rosette Identification Guide

The setting and the first impression

The Blushing Rosette is one of the more confusing fungi to meet for the first time, because it looks like a bracket fungus that has forgotten to find a tree. You come across it on the ground: on a mown lawn, along a woodland path, in a churchyard, at the edge of a car park, in a hedge bottom, often several metres from the nearest visible stump. Its shape is unpredictable, which is a large part of its character. In the best-developed form it is a rosette, a cluster of overlapping cream to buff fan-shaped or funnel-shaped caps rising from a short common base like a coarse flower. In other collections it is a single shallow funnel on a stubby stem, an irregular lumpy crust smothering fallen twigs, or a shapeless sterile white mass that looks like a spill of dough. Once you learn to expect that variability, the species becomes much easier to recognise.

Reading the upper surface

The cap surface is cream, pale buff or ochre when fresh, becoming darker ochre-brown to reddish-brown with age and from the centre outwards. It is finely tomentose or velvety to the touch when young, often with faint concentric zoning and a paler, thickened, slightly wavy margin. Individual caps are usually 5-15 cm across, but a fused rosette can be 25 cm or more overall, and the fans are typically lobed, irregular in outline and often split. Press the upper surface and watch: fresh material stains reddish to reddish-brown where handled, and older fruit bodies frequently show diffuse rusty-red bruising and blotching across the top. Debris and grass blades are often engulfed by the growing margin, and where the fungus grows through turf the caps may be partly buried in the sward.

The spore-bearing surface

Turn a cap over. The underside carries pores, so this is a polypore, but it is a polypore that rarely keeps its pores tidy. Fresh, the surface is white to cream and the pores are angular and irregular, roughly 1-3 per millimetre, but they quickly become elongated, maze-like, torn, or broken up into flattened tooth-like plates, so a single fruit body can show round pores in one place and ragged teeth in another. The pore layer runs down onto the stem where one is present. Now the two characters that identify the species: press the pore surface, and it flushes pink to red and then reddish-brown within a minute or two; and look at fresh, actively growing margins on a humid morning, when the fungus commonly weeps clear to reddish guttation droplets that sit on the underside like beads and leave rusty stains where they dry.

Stem, base and what lies beneath

The stem, where there is one, is short, stout, off-centre or central, whitish to buff, felty, and often tapering into a narrow rooting extension that disappears into the soil. This is worth excavating. Follow the base down with a trowel or a knife and you will usually find that it is attached to buried wood: a dead root, an old stump crown below the turf, or a piece of buried timber. That habit explains why a wood-decay fungus keeps appearing in the middle of a lawn, and confirming the buried attachment is one of the most satisfying steps in the identification. There is no ring, no volva and no veil.

Flesh and section

Cut the fruit body vertically and look closely at the section, because the flesh is two-layered and this is a genuine diagnostic feature. The upper layer is soft, pale and slightly spongy; the lower layer, next to the tubes, is firmer, tougher and more compact, and a fine dark line can often be seen between them. Overall the flesh is whitish to pale buff, and it too reddens where cut, slowly turning pinkish then rusty-brown. Fresh fruit bodies are soft and watery; old ones dry to a hard, light, corky mass that persists for weeks and loses the reddening reaction entirely.

The sterile form

One more thing to expect: this species regularly produces a sterile, aborted form, which is where its genus name comes from. Instead of forming caps and pores it develops as a lumpy, white to cream, sterile mass, sometimes the size of a fist, with an uneven, warted or brain-like surface and no visible pore layer at all. These can be baffling. Cut one open and look for the same soft, whitish, two-textured flesh and the same reddening reaction on exposure; check the base for buried wood; and look nearby for normal fruit bodies, which are often present in the same colony.

Taking a spore print

Trim a cap, sit it pore-surface-down on black paper, cover it and leave it overnight. The deposit is white and light, so a dark background is necessary. Under a microscope the spores are small, hyaline, smooth, thin-walled and broadly ellipsoid, roughly 4.5-6 by 3-4 micrometres. A white print rules out several of the brown-spored terrestrial polypores that occupy similar ground.

Substrate, season and ecology

Abortiporus biennis is a white-rot fungus of broadleaved wood, and it specialises in roots and buried timber rather than standing trunks. It is common on and around dead roots of oak, beech, poplar, willow and many other hardwoods, and it turns up in lawns, parks, gardens, path edges and hedgerows, particularly where trees have been felled and the root systems left in the ground. It is annual, with fruit bodies appearing from midsummer through autumn, sometimes persisting into winter as dried remnants. Because it works on buried roots, colonies can persist and fruit in the same spot for years after the tree that fed them has gone.

Separating it from look-alikes on morphology alone

Meripilus giganteus forms much larger terrestrial rosettes at the base of beech and other hardwoods, but its flesh and pore surface blacken conspicuously where bruised or on drying, its caps are grey-brown and radially streaked, and its pores are fine, round and regular.

Grifola frondosa also grows in rosettes from the base of oaks, but its caps are numerous, small, grey-brown and spoon-shaped, its pore surface stays white without reddening, and its flesh is fibrous with no distinct two-layer structure.

Bondarzewia berkeleyi is much larger and thicker with coarse angular pores, cream to buff caps, and no red bruising.

Coltricia perennis grows on the ground in similar places with a neat funnel shape and a central stem, but it is thin, tough and leathery, has a rusty-brown zoned cap and a brown pore surface, and drops a brown spore print.

Trametes and Bjerkandera species are attached directly to visible wood as thin brackets and lack the reddening pore surface and the guttation droplets.

Podoscypha and Sparassis form terrestrial rosettes too, but the first is thin, leathery and smooth beneath rather than pored, and the second is a mass of flattened wavy lobes with a smooth fertile surface.

Field checklist

Terrestrial rosette or funnel on lawn or path edge, cream to ochre velvety cap reddening on handling, irregular angular to maze-like or toothed white pore surface that flushes pink-red on pressure, reddish guttation droplets on fresh margins, two-layered whitish flesh, short stout rooting stem attached to buried hardwood root, white spore print, summer to autumn, plus the occasional sterile white lumpy form.