Crowded Parchment

Stereum complicatum is one of the most abundant wood fungi of eastern North American hardwood forests, so common on fallen oak branches that it is often the first crust fungus a beginner learns. Its Latin epithet refers to the way adjacent fruit bodies fold and fuse together, and its English name captures the same idea: crowded, overlapping little fans running along a branch for its whole length.

The genus Stereum is defined by a smooth fertile surface. Where a polypore has tubes and a toothed fungus has spines, a Stereum simply presents a flat, even underside with no visible structure at all — a feature that makes the genus easy to recognise even when the species is not.

This species is smaller and brighter than most of its relatives, with thin, leathery, tan to orange fans rarely more than a couple of centimetres wide. It fruits abundantly in cool wet weather and its dried fruit bodies persist on wood through the whole year, reviving in colour after rain.

Fruit body

Individual caps are 0.5–2.5 cm wide, thin, leathery and fan- to shell-shaped, attached along a narrow base or a short lateral point. They grow in dense crowds and repeatedly fuse edge to edge, often forming a continuous frill that spirals around a branch. On the underside of wood, colonies may remain partly resupinate with only a narrow reflexed lip.

Upper surface

The upper side is finely velvety when young, becoming smooth with age, and shows faint concentric zoning in shades of orange, cinnamon, tawny and buff. The margin is thin, wavy and often paler yellow. Weathered specimens fade toward greyish tan and may host green algae.

Fertile surface and flesh

The underside is smooth and even — no pores, teeth or wrinkles — and coloured bright orange-tan to pale ochre, paler than the top. It does not exude any liquid when scratched or cut, and the surface does not bruise to a different colour. The flesh is very thin, tough and pliable, drying rigid. The spore deposit is white.

Crowded Parchment fruits on dead broadleaf wood, with a marked preference for oak, and is especially typical of fallen branches, twigs, and brush piles of small-diameter slash. It also occurs on hickory, maple, beech and other hardwoods, and readily colonises attached dead branches still in the canopy.

It is present year-round as persistent dried fruit bodies, with new growth flushing in autumn, winter and spring during wet, cool weather. The species is common and widespread through eastern North America, with related forms reported elsewhere.

The fungus is a saprotroph causing a white rot, breaking down lignin and cellulose in small-diameter hardwood and reducing branch litter to soft pale fibre. Because it specialises in thin branches and twigs, it is a major agent in recycling the fine woody debris layer of hardwood forests.

Colonisation typically begins in branches that die while still attached to the tree, and fruiting continues after they fall. The leathery fruit bodies are effectively perennial in appearance if not in function: they dry hard, survive freezing and drying without disintegrating, and resume spore production when rewetted.

Stereum ostrea, the False Turkey Tail, is much larger — often 3–7 cm wide — with bold concentric zones of brown, buff and greenish grey and a broadly flaring fan shape; it grows in scattered tiers rather than dense fused crowds. Stereum hirsutum has a noticeably hairy upper surface and is a stronger yellow, with larger, more irregular caps.

Stereum gausapatum is superficially similar in size and colour but releases a red juice from the fertile surface when scratched while fresh; Stereum complicatum never does. Trametes versicolor and other true turkey tails have a distinctly poroid underside with fine round pores, immediately separating them from any smooth-surfaced Stereum. Trichaptum biforme shares the thin fan form but has a violet-tinged, toothed to poroid underside.