White saddle or Elfin saddle

Cap 2-4 cm, irregularly saddle-shaped, with 2-4 lobes that look like crumpled fabric. Color white or creamy white, with a yellowish tinge in wet weather. Surface smooth on the outside (where the hymenium is), finely warty underneath. Partly fused to the stem at the top. Margins contorted, uneven.

Cap 3-5 cm, irregularly saddle-shaped, with 2-4 lobes. Color dark gray, graphite, almost black in old specimens. Surface smooth, with a silky sheen in wet weather. Margins wavy and contorted. Partly fused to the stem at the top.

Smooth hymenium on the upper (outer) surface of the cap lobes. Ascomycete structure — spores form in asci. Spore print white. Spores ellipsoid, smooth, with one large oil droplet.

Smooth hymenium on the upper (outer) surface of the cap lobes. Ascomycete structure — spores form in asci. Spore print white. Spores ellipsoid, smooth, 17-20 × 10-13 µm.

Stem up to 10 cm tall, 1-2.5 cm thick, cylindrical, hollow inside. Color white, smooth to the touch, BUT with prominent lengthwise ribs (grooves) running its whole length. This is the key feature — a ribbed white stem.

Stem up to 6 cm tall, 1-2 cm thick, cylindrical, hollow inside. Color pale gray, darkening toward the base. Surface with prominent lengthwise ribs and distinctive pits (lacunae) — hence the name. The ribbed structure is like that of crispa, but the color is completely different.

The flesh is thin, waxy and brittle, white. Doesn't change color when cut. Fragile texture — the mushroom easily falls apart if handled carelessly.

The flesh is thin, waxy and brittle, grayish white. Doesn't change color when cut. Fragile texture.

Faint, nondescript mushroomy smell. Don't taste it raw — potentially toxic.

Faint mushroomy smell, no sharp notes. We don't taste it — potentially toxic.