Gymnosporangium cornutum

On still-green fallen leaves on the ground of Sorbus aucuparia.

This study corresponds to the aecial stage of the species.

Peridial cells of the aecia very irregular, polyhedral, very thick-walled, ornamented with darker striations arranged radially, with a hyaline cell lumen.

Aeciospores globose to very slightly angular, greenish-brown under the microscope, thick-walled, with faint granular internal content.