cepistipes

Onion-stalked Armillaria

Armillaria cepistipes is a weakly pathogenic to saprotrophic species that typically colonizes the roots and bases of deciduous trees. It is morphologically similar to A. gallica but is generally more slender and less scaly. The species is known for its rhizomorphs which can form extensive networks in the soil. It is often found in dense clusters or gregarious groups on wood that is in an advanced state of decay. The mushroom features a cap that is initially convex and later flattens, often with a hygrophanous margin. The stem is characteristically club-shaped (cepistipes means 'onion-stemmed'), widening towards the base. It is a distinct biological species (NABS XI in North America, EBS B in Europe) and is often used in comparative pathology studies due to its lower virulence compared to A. ostoyae.