Crepidotus crocophyllus

Crepidotus crocophyllus is the most colourful of the common creps. Where most species in the genus are plain white or buff, this one combines a pale cap dressed with tawny to rust-brown fibrillose scales and, underneath, gills of a striking saffron, apricot or orange-yellow that only later dull to cinnamon-brown as spores mature.

The epithet comes from the Greek krokos, saffron, and phyllon, leaf — literally saffron-gilled — and that character is the single most useful field mark. It is a member of the same genus as the white creps, sharing the stalkless lateral attachment, the fan or shell outline and the brown spore deposit, but no other widespread species in the group has yellow-orange gills.

It is a widespread species of temperate hardwood forest, particularly common in eastern North America and recorded from Europe and Asia, and it fruits in shelving groups on logs and branches through the warmer part of the year. Colour intensity varies with age and weather, so young specimens show the character best.

Cap

The fruiting body is 1–5 cm across, fan-shaped, kidney-shaped or semicircular, attached laterally to wood and often shelving in overlapping groups. The surface is whitish to pale yellowish or buff, overlaid with fine appressed fibrils and small scales in tawny, rust-brown or reddish-brown, densest near the attachment point and thinning towards the margin. The cap is dry, not gelatinous, and the margin may be slightly inrolled when young.

Gills

The gills radiate from the attachment and are close, narrow and initially a vivid saffron, apricot, orange-yellow or golden colour — the diagnostic feature. With maturity they darken through ochre to cinnamon or dull brown as the spore load builds, though traces of the yellow tone usually persist near the gill edges and in shaded specimens.

Stipe

There is no true stipe. The cap attaches directly to the substrate at a lateral point, occasionally with a very short rudimentary stub and usually with a small tuft of white mycelium at the attachment.

Flesh and spore print

The flesh is thin, soft and whitish to pale yellow, with no colour change when cut or bruised. The spore print is brown to cinnamon-brown. Microscopically the spores are globose to broadly ellipsoid and finely ornamented, and pigmented hyphae in the cap surface account for the scaly tawny flecking.

This species fruits on dead hardwood — fallen logs, stumps, large branches and woody debris — and shows a preference for well-rotted, barkless wood in damp shaded situations. Oak, maple, beech, birch, poplar and other broadleaves are typical hosts, and it occasionally occurs on conifer debris. Fruit bodies are usually gregarious, forming rows and overlapping tiers along the flank or underside of a log.

The fruiting season runs from late spring through summer to autumn, peaking during warm humid weather. It is common in the deciduous forests of eastern North America and is also recorded across Europe and temperate Asia, generally as a scattered but recognisable component of the wood-decay fungus community.

Crepidotus crocophyllus is saprotrophic and causes a white rot, degrading lignin along with cellulose so that colonised wood becomes pale, soft and fibrous. It occupies mid to late stages of decay, arriving after the bark has fallen and the surface has begun to soften, and it forms extensive sheets of mycelium just beneath the wood surface.

The stalkless, laterally attached fruit body is adapted to producing spores from vertical and overhanging surfaces, with the cap growing outwards so that the gills hang free below. Fruiting is strongly tied to humidity, and dense flushes typically follow sustained summer rain, with brown spore dust often visible on caps growing beneath others in a tier.

Flat Crep (Crepidotus applanatus) is the most similar in shape but has a smooth white cap without tawny scales and gills that begin white before turning cinnamon, never saffron. Peeling Oysterling (Crepidotus mollis) is larger, has a gelatinous elastic layer under the cap surface and pale buff gills that darken to brown without any orange phase. Variable Oysterling (Crepidotus variabilis) is much smaller, grows on twigs and has a downy white cap with pale pinkish-brown gills.

Orange-gilled wood fungi in other genera differ in spore colour and structure. Phyllotopsis nidulans is larger, densely felty-hairy and bright orange all over including the cap, with a pinkish spore print. Panellus stipticus is tan, tough and has a distinct short lateral stub with a white spore print. Crepidotus cinnabarinus is a small red-orange species with red-flecked cap and gills, a much stronger and more uniform colour than the saffron of C. crocophyllus.