E-Flora BC: Electronic Atlas of the Flora of British Columbia

Summary:
Sawadaea bicornis is included as an example of Erysiphales (powdery mildews). Powdery white mycelium appears on maple leaf surfaces in late summer and fall in BC. (Allen). The anamorph is Oidium aceris Rab. (Funk). Note that downy mildews (Peronosporales in Oomycota) and dark mildews (Meliolales in Ascomycota) are different.

includes BC

Microscopic:
spores 22-26 x 13-15 microns, elliptic, nonseptate, colorless; asci 8-spored, 70-95 x 45-55 microns, 4-12 in number, pear-shaped, perithecia superficial on leaf, nearly spherical, "nonostiolate, black, up to 170 microns diameter, on the upper half bearing many short (approximately 150 microns) spreading appendages forked at the tip, the branches recurved to form a double hook"; conidia 25-35 x 15-20 microns, (Funk)