Netted Crust

Netted Crust is one of the commonest pale crusts on dead attached branches in hedgerows and woodland edge. It spreads in long strips along the underside of a branch, sometimes running for many tens of centimetres, and its fertile surface is patterned with a shallow, irregular net of low ridges — the "merulioid" condition, intermediate between a smooth crust and a true pored fungus.

A second helpful feature is the way the margin behaves. Rather than being fused tightly to the bark all round, the edges are white, soft and cottony and frequently lift free, curling outward into small reflexed flaps that look like the beginnings of a bracket.

The species has been shuffled between genera and appears in older literature as Meruliopsis corium or Merulius corium; Byssomerulius corium is the name in current use. It sits in the Irpicaceae among other soft, whitish wood-decayers.

Fruiting body

Resupinate but with the margin usually free and reflexed, forming narrow undulating flaps a few millimetres to a centimetre wide. Patches merge into extensive sheets along branch undersides.

Fertile surface

White, cream or pale buff, developing a shallow network of low, blunt, irregular ridges and shallow pits — never regular round pores and never true spines. Older material can look faintly wrinkled to almost smooth.

Margin and texture

The edge is white, cottony or fibrillose and clearly free of the wood. The whole fruiting body is soft and pliable, almost leathery when fresh, and stiffens on drying.

Flesh and spore print

Flesh is thin, white and soft, with no colour change when cut or bruised. The spore print is white.

Occurs on dead attached branches and fallen sticks of broadleaved trees and shrubs, with hazel, ash, willow, hawthorn and oak all frequently used. It is especially common in hedgerows, scrub and woodland margins, and characteristically fruits on the shaded lower side of the branch.

Fruiting bodies persist all year and are at their best in autumn and winter. The species is widespread and common in Europe and across the temperate Northern Hemisphere.

Byssomerulius corium is a saprotroph causing a white rot in small- to medium-diameter dead wood. It commonly establishes in branches that have died back while still on the tree, then continues to decay them after they fall.

As a coloniser of fine woody debris it is an important part of the hedgerow decay community, sharing that habitat with Peniophora and Schizopora. Its extensive spreading sheets can occupy a whole branch, and the netted surface increases the fertile area over which spores are produced.

Schizopora paradoxa is the main confusion because both are whitish crusts on hardwood branches. Schizopora is firmer and more closely attached, and its surface is genuinely poroid, with pores that split and become tooth-like; it does not form free cottony flaps at the edge.

Irpex lacteus is whiter still and clearly toothed, with hairy reflexed caps. Phlebia tremellosa has the same netted sculpture but is gelatinous and tinted orange-pink. Cylindrobasidium laeve is pale and soft too but has a smooth to slightly bumpy surface without a net of ridges.