Gymnosporangium sorbi (Arthur) F. Kern 1911

Gymnosporangium sorbi (Arth.) Kern, Bull. N. Y. Bot
Gard. 7 : 438. 1911.
Aecidium Sorbi Arth. Bull. Torrey Club 33 : 521. 1906.
Pycnia epiphyllous, numerous, gregarious, in small groups on discolored areas, noticeable, subepidermal, honey-yellow becoming brownish, conoidal, 110-130 /^ in diameter, 70-80 ji high ; ostiolar filaments 30-45 }i long.
1. Aecia hypophyllous, numerous, gregarious, in small groups of 4 to 7, arising from slight swellings on discolored spots, or often more numerous on larger swellings on the veins or rachis, cupulate, 0.2-0.4 mm. high by 0.2-0.3 mm. in diameter; peridium colorless, margin nearly erect, erose; peridial cells rhomboidal , 30-45 m long, slightly overlapping, the lumen small, the outer wall much thickened, 10-13/^, transversely striate, smooth, the mner and side walls thinner, 3-5//, somewhat striate, moderately verrucose ; aeciospores broadly ellipsoid, usually somewhat angular, 23-27 by 27-39// ; wall pale-yellow, thick, 3-4//, minutely verrucose. On Malaceae :
Malus rivularis (Doug.) Roem., British Columbia.
Sorbus occtdentahsJS. Wats.) Greene, Washington ; British Columbia.
Sorbus scopuhna Greene, Alaska.