Scaly Wood Mushroom Identification Guide

The first impression

The setting is woodland floor rather than pasture: needle litter under spruce or pine, mossy ground in mixed plantation, or rich humus along a woodland ride. You see a tall, fairly stately mushroom, cap 6 to 12 cm and sometimes larger, standing well clear of the litter on a slender straight stalk. From above the cap looks brown and streaky, from a distance almost like a young parasol, and there may be two or three fruitbodies together or a small scattered troop.

Turn one over and the gill colour immediately tells you the genus family you are in: bright deep pink in young material, moving to dark brown with age, and gills that are free of the stipe. Add a ring on the stalk and you have narrowed things to the Agaricus group before you have made a single cut.

Reading the cap

The cap begins hemispherical to squat and barrel-shaped, then opens to convex and finally almost flat with a slightly wavy margin in large specimens. The surface is dry and not polished: the outer skin breaks up into flat, appressed, radially arranged fibrillose scales in reddish-brown, chestnut or purplish-brown, set on a paler cream to buff ground.

Read the scale pattern deliberately. Here they are largely flat rather than upturned, densest and darkest over the centre where they may fuse into an almost solid cap, and progressively more separated toward the margin where the pale ground shows through between them as fine streaks. In dry weather the margin may fray and split; in wet weather the scales flatten and darken. There are no loose patches of veil sitting on top of the cap.

The gills

Gills are crowded, narrow, and free, ending clear of the stipe. Their colour sequence is a proper diagnostic tool if you look at more than one age of fruitbody. In this species the young gills are already a clear, quite bright pink at the button stage rather than passing through a long pale or greyish phase, then darken through dull pink and greyish-brown to a deep chocolate or blackish-brown at maturity.

That early pink is a useful pointer within the genus, because several relatives keep their gills pale and whitish for much longer before flushing.

The stipe, ring and base

The stipe is 6 to 12 cm long and comparatively slender, 1 to 2 cm thick, cylindrical and only slightly thickened at the base. Critically, it is not abruptly bulbous, and there is no sac or volva. Dig the whole thing up to check, because a snapped stipe destroys the character.

Colour is white to cream at first, rapidly discolouring reddish or reddish-brown wherever it is handled, scratched or scuffed, especially over the lower half. The ring sits high on the stalk, is thin, white, simple and pendant, hanging like a skirt, and it often tears or collapses against the stipe in older material. The underside of the ring is not elaborately patterned with cogwheel-like scales.

Below the ring the stipe may be very finely fibrillose or slightly scurfy, and the base is usually attached to litter by white cords.

Flesh and colour change

This is the decisive test, so do it properly. Slice a fresh fruitbody vertically from the top of the cap through the middle of the stipe to the base, and watch the cut surface for two to five minutes.

The flesh is white and rather thin in the cap. On cutting, it turns a clear reddish, blood-red or brick-red, most strongly in the stipe, particularly toward the base, and in the flesh immediately above the gills. The colour comes up steadily rather than instantly and then dulls to brownish over a longer period. Rubbed cap and stipe surfaces redden the same way.

Equally important is what does not happen: there is no bright chrome-yellow flush in the base of the stipe. Testing this properly means cutting right through the very bottom of the stalk and looking within seconds, because that yellow reaction is the character that separates a whole different section of the genus.

Taking and reading a spore print

A print is quick and unambiguous. Cut the stipe flush, place the cap gills-down on white paper, cover it, and leave four to eight hours. The deposit reads deep chocolate brown to purple-brown, dense and obvious. That result rules out the white-spored parasols and the pink-spored shields at a stroke.

Under a microscope the spores are smooth, thick-walled and ellipsoid, and this species is characterised by spores at the longer end of the range for its group, a detail worth measuring if you are working through the section carefully.

Substrate and season

The species is a litter decomposer of woodland soils. It favours conifer and mixed woodland, fruiting in needle beds, mossy banks and humus-rich ground along tracks and clearings, and it is far less a creature of open grassland than the field-dwelling members of the genus. Late summer to late autumn is the season, and fruitings tend to be small: a few fruitbodies scattered over a metre or two rather than a fairy ring.

Recording whether the surrounding trees are conifer or broadleaved and whether the ground is litter or turf is a genuine part of the identification, because habitat helps split the reddening woodland species from their grassland cousins.

Separating it from the look-alikes

Agaricus sylvaticus and the rest of the reddening woodland group. The closest relatives, all sharing the reddening flesh. Compared with them this species is generally more robust, with a broader cap, darker and more sharply defined flat brown scales that contrast strongly with the pale ground, and gills that are pink early. Agaricus sylvaticus is more slender, with finer, more diffuse and browner scales, and its reddening is usually a shade weaker. Spore length under a microscope is the character mycologists actually use to finish the job.

Agaricus impudicus. Also woodland and also scaly, but the scales are greyish-brown to smoky rather than warm reddish-brown, and the flesh reddens weakly or barely at all, which is the clean field separation.

The Prince, Agaricus augustus. Larger and stouter, with golden-brown to tawny scales arranged in a more concentric pattern on a yellowish ground, a thicker double-edged ring, and surfaces that flush yellow when rubbed rather than red.

Wood and horse mushrooms in the white group, such as Agaricus silvicola and Agaricus arvensis. These have essentially smooth white caps without brown scales, and they flush yellow rather than red when rubbed.

Agaricus xanthodermus. White to greyish with a smooth or slightly cracked cap, and diagnostically it produces an intense chrome-yellow stain in the extreme base of the stipe on cutting. Always make that basal cut before settling on a reddening species.

Parasols, Macrolepiota and Chlorophyllum. Superficially similar scaly caps and ringed stipes, but their gills stay white or cream, never pink, and the spore print is white. A single print separates them.

Amanita species. Free white gills, white print, and a sac, bulb or volval remnants at the base. The chocolate print and pink young gills of this species make the distinction immediate.

A quick field checklist

Woodland litter under conifers or mixed trees, flat reddish-brown appressed cap scales on a pale ground, free gills pink from an early stage, a thin pendant simple ring, a slender non-bulbous base, flesh reddening clearly on cutting with no chrome-yellow in the base, and a chocolate-brown spore print.