Oyster mushroom or Shiitake

Cap 5–25 cm across, rounded or ear-shaped in young mushrooms, then fan-shaped or oyster-shaped (hence the English name oyster mushroom). Surface smooth, moist, from dark grey or grey-blue in young ones to pale grey or almost white in mature ones. Margin wavy, thin.

The cap is 5–20 cm across, usually 5–10 cm in shop mushrooms. Young caps are domed with a tightly inrolled edge, then become convex and finally almost flat, with a wavy margin in old mushrooms.

The colour ranges from pale tan to dark brown or reddish brown, paler towards the edge and fading with age. The surface is felty and fibrous, with small whitish scales that are densest near the margin, where white shreds of the veil hang. Some varieties, known in China as flower shiitake (huagu), have caps that crack into a white network on a dark background. This comes from the way they are grown and is not a separate species.

Gills crowded, whitish or cream, running from the cap down the stem. In young mushrooms the gills are tightly packed; in old ones they spread apart. Spore print white or pale lilac.

The gills are crowded, white or cream, and attached to the stem, sometimes running slightly down it. In young mushrooms a white cobwebby veil covers them. With age and handling the gills turn brownish and their edges become ragged and saw-toothed.

The spore print is white. That is the key feature separating shiitake from brown mushrooms with a rusty print, including the poisonous funeral bell.

Stem 1–5 cm tall (or almost absent in side-attached mushrooms), 1–2.5 cm thick, firm, off-centre or lateral, white or slightly grey. No ring and no volva.

The stem is 3–5 cm tall and about 1 cm thick, central or slightly off-centre, often curved and narrowing towards the base. It is firm, tough and fibrous, pale brown, with woolly scales below the cap.

There is no true membranous ring, only a fibrous ring zone left by the veil, and no volva at the base.

Flesh white, firm in young mushrooms, more fibrous and tough in mature ones, especially in the stem. Taste mild, slightly anise-like. It soaks up flavours well in cooking.

The flesh is white, firm and springy, thick in the centre of the cap and thin at the edge. In the stem it is tough and fibrous. A cut surface hardly changes colour, though the flesh slowly browns in old mushrooms. The taste is mild and rich, with a strong umami note.

Smell pleasant, subtly anise-mushroomy. Fresh oyster mushrooms smell soft and unobtrusive; when fried, the aroma grows stronger and closer to the classic mushroom smell.

The smell is pleasant, mushroomy and slightly spicy. It is noticeably stronger in dried shiitake, which is why dried mushrooms are added to dishes for their aroma.