Summary: Diplocarpon rosae forms black spots on rose leaves, and rarely minute fruiting bodies. The conidial stage, black spot of rose, is widely distributed wherever the rose is cultivated.
Microscopic: spores 20-25 x 5-6 microns, elliptic, colorless, unequally 2-celled, constricted at the septum; asci 8-spored, reaching length of 70-80 microns and width of 15 microns, subclavate [more or less club-shaped]; paraphyses filiform [thread-like], enlarged at tips; conidia 18-25 x 5-6 microns, "formed on erumpent acervuli, 1-septate and constricted at the septum"