Cluster Cap

Connopus acervatus, commonly known as the cluster cap, is a saprotrophic basidiomycete fungus in the family Physalacriaceae. This small to medium-sized mushroom produces tightly clustered fruiting bodies on decaying hardwood stumps and logs, particularly in temperate and boreal forests of the northern hemisphere. The cap is convex to flattened, typically reddish-brown to tan with a paler margin, and the gills are crowded and whitish to pale. The stipe is tough and fibrous, often twisted or curved at the base where clusters merge. Connopus acervatus causes white rot decomposition in its woody substrates, breaking down both cellulose and lignin. It is a common autumn and early winter species in broadleaf forests and mixed woodland across Europe, North America, and Asia. The species has occasionally been classified within related genera including Collybia and Gymnopus in older literature, and its taxonomic placement has been revised with molecular phylogenetic studies. It is classified as Least Concern by the IUCN, being widespread and common in suitable forest habitats.