Botryosphaeria visci

A study corresponding to the anamorph (asexual or conidial stage) of the species, known as Sphaeropsis visci, on mistletoe leaves (Viscum album), with pycnidia appearing scattered but abundantly across the leaf surface.

Pycnidia globose, immersed in host tissue, 0.3 to 0.5 mm in diameter, blackish, with a single internal locule and an apical pore (ostiole) through which conidia are discharged.

Peridial wall hyphae of textura angularis, 30 to 55 µm in diameter, containing abundant greyish-brown intracellular pigment.

Conidiogenous cells cylindrical, subglobose to clavate, hyaline, 7 to 15 µm long and 4 to 12 µm wide.

Conidia ellipsoidal to oblong, smooth- and moderately thick-walled, brown under the microscope, 40 to 55 µm long, 16 to 23 µm wide, containing copious refringent oil droplets of varying size inside.