Armillaria

Physical Characteristics

Armillaria species typically grow in dense clusters, as seen in the image. The caps can range in color from honey-yellow to dark brown, often darker towards the center. They are convex when young, flattening with age, and can have small scales. Gills are typically adnate to decurrent, white to cream, sometimes darkening with age. Stems can be fibrous and often have a ring (annulus) which may be persistent or disappear. Spore print is white.

Habitat & Growing Conditions

These fungi are typically found on living or dead wood, including stumps, roots, and buried wood. They can grow terrestrially if there is buried wood. They are often found in deciduous and coniferous forests, as well as in gardens and parks.

Season & Fruiting Time

Armillaria species are often found in late summer and autumn, but can appear earlier or later depending on the specific species and local climate conditions.

Similar Looking Species

Several other fungi can grow in clusters on wood. Galerina marginata is a deadly toxic species that can sometimes resemble Armillaria, but it has a brown spore print and typically lacks a prominent ring. Pholiota species may also appear similar but generally have yellowish to brownish spore prints and often feature scales on the cap and stem. Desarmillaria tabescens (Ringless Honey Mushroom) is very similar but lacks a prominent ring and has a darker cap.

Ecological Role

Armillaria species are primarily parasitic on trees, causing root rot and white rot of wood. They can also grow as saprophytes on dead wood. They play a significant role in nutrient cycling by decomposing wood, but as pathogens, they can cause considerable damage to forests and orchards.

Identified on: 9/27/2025

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