Coprinopsis atramentaria, commonly known as the Common Ink Cap or Tippler’s Bane, is a saprobic mushroom that grows in clusters or dense groups on buried wood, lawns, gardens, or disturbed soil—often in urban areas. It appears from spring through fall and is widely distributed across temperate regions. The species name atramentaria comes from the Latin atramentum, meaning “black ink,” referring to the dark liquid produced when the cap deliquesces with age (Kuo, 2004).

This mushroom contains the compound coprine, which causes a toxic reaction when alcohol is consumed within several days of ingestion. Symptoms include flushing, nausea, and rapid heartbeat (Beug, 2024).

The cap is gray to gray-brown, initially oval or bell-shaped, and reaches 1–4 inches (3–10 cm) wide. As it matures, the cap flattens, becomes grooved, and eventually dissolves into black ink. The surface may be slightly scaly near the center. Gills are free from the stem, crowded, and change from white to black as they liquefy. The stem is smooth, white to grayish, and hollow. The spore print is black.