A genus of fungi; in D. concentrica, the dark-coloured, hemispherical fruit bodies are about 5–10 cm in diameter and are formed annually. When cut open the fruit bodies show very characteristic concentric bands of black and white. Early in the season the surface is coated with pale-brown, powdery conidia. Later, perithecia are formed in the outer layer of the fruit body. D. concentrica is found chiefly on ash (Fraxinus excelsior).
Subjects: Plant Sciences and Forestry.