Split Porecrust

Split Porecrust is one of the most frequently encountered wood-decay fungi in temperate woodland, yet it puzzles beginners because its fertile surface refuses to settle on a single form. Near the advancing margin the pores are small and reasonably round; further in they elongate, then split along their walls into ragged plates, and in the oldest parts they break down entirely into flattened, irregular teeth. That variability is the reason for the epithet paradoxa.

The fungus grows as a flat sheet on the underside of dead wood, sometimes spreading for a metre or more along a fallen branch. It is tough and leathery when fresh and hardens on drying, and its colour runs from clean white through cream to pale ochre with age.

Recent classifications place the species in Xylodon as Xylodon paradoxus, though Schizopora paradoxa remains widely used. Whichever name is applied, it is a species worth learning early simply because it appears on so many logs.

Fruiting body

Entirely resupinate, forming extensive sheets closely attached to the wood, from a few centimetres to over a metre long. Thickness is one to three millimetres.

Pore surface

Highly variable: round to angular pores at roughly one to three per millimetre near the margin, becoming elongated and slot-like, then lacerate, and finally reduced to flattened irregular teeth in the oldest areas. White or cream when fresh, ageing to pale ochre or buff.

Margin

White, finely cottony or fibrillose, thinning gradually onto the wood.

Flesh and spore print

Flesh is thin, white, tough and leathery when fresh, hard and rigid when dry, with no colour change on cutting or bruising. The spore print is white.

Grows on dead broadleaved wood of almost any kind — fallen branches, logs, stumps and standing dead stems — with oak, beech, birch, hazel and ash all commonly used. It occurs occasionally on conifer wood. It strongly favours the shaded underside of fallen wood, where humidity remains high.

Fruiting bodies persist all year and are among the most reliably present fungi on woodland debris in any season. The species is widespread and abundant throughout Europe and much of the temperate Northern Hemisphere.

Schizopora paradoxa is a saprotroph producing a white rot, degrading lignin along with cellulose so that the decayed wood becomes pale, soft and fibrous. It colonises wood at a range of decay stages and can dominate large surfaces of a fallen branch.

Its capacity to spread as a thin sheet across the underside of wood, and to persist through dry periods and resume growth when damp returns, makes it a long-term occupant rather than a brief fruiting event. Spores are released from the pores and teeth across an unusually large fertile area.

Irpex lacteus is the closest match but is whiter, more consistently toothed rather than poroid, and usually forms narrow reflexed caps with a hairy upper surface — something Split Porecrust does not do.

Byssomerulius corium has only a shallow net of low ridges rather than true pores, is softer, and lifts free at the margin into cottony flaps. Resupinate Trametes and Antrodia species show regular, evenly sized pores that do not fray into teeth, and Antrodia species often have a more distinct, firmer context layer beneath the tubes.