Blackening brittlegill or Silky piggyback

Cap 1.5–2.5 cm. Bell-shaped at first, then flattening. Color: white → reddish or grayish. Surface smooth, not cracked.

Cap 8-20 cm across; in young mushrooms hemispherical to flat with an inrolled margin, later becoming funnel-shaped. Color white when young, turning dirty gray, ash-gray, then blackish to anthracite black with age. The cap darkens when pressed — unevenly in young specimens. Surface smooth, slightly sticky in wet weather.

Gilled hymenophore. Spore print white. Spores ellipsoid, 5–6 × 3–4 µm. Secondary chlamydospores are often formed.

Gilled hymenophore — the gills are attached to the stem, distant and thick, typical of the genus Russula. In young mushrooms — whitish, when damaged they redden to brownish-black, darkening with age to gray, then black. Spore print white.

Stem 1–5 cm tall, 2–5 mm thick. Hairy, often bent, hollow, fibrous. Whitish to grayish. No ring or volva.

Stem 4-8 cm tall, 2-4 cm thick, thick, fleshy, cylindrical, relatively short. Color white when young, turning gray, then blackish with age. Surface smooth. No ring.

flesh thin, fragile, white. No notable color changes.

Flesh firm, fleshy, white when young. When cut, a two-phase reaction slowly unfolds (over 5-10 min): first it reddens to wine-red or bright carmine, then after a few more minutes it blackens to anthracite black. This is the classic diagnostic feature of the species. Faint mushroomy smell.

Faint, mushroomy. No sharp notes.

Faint, pleasant, mushroomy, with no distinctive notes.