Anamorph: Phomopsis phaseoli (Desm.) Sacc. (1915). Alpha-conidia 5-12 x 2-5 µm; beta-conidia 14-30 x 1-2 µm.
Teleomorph: stromata with host surface ± blackened over wide areas, with ostioles erumpent separately, dorsal zone along bark surface, ventral zone usually absent or occasionally present laterally or along the pith. Ascomata 160-350 x 110-200 µm, scattered or crowded, ostioles short-conical to elongate-filiform sinuous and 120-400 x 50-80 µm. Asci 28-46 x 5.5-8 µm, clavate. Ascospores 8-12 x 2-3.5 µm, broad-fusiform, constricted at the septum, slightly acute at the ends, guttulate.
At present a confused species, often separated into four varieties or special forms based on host range and pathogenicity but probably inseparable by morphology. It is not clear whether UK records refer to the pathogen or to generalist saprobes colonizing dead or moribund host tissue.