About Triphragmium ulmariae (DC.) Link
Triphragmium ulmariae (DC.) Link is a species of rust fungus belonging to the family Phragmidiaceae. This fungus causes meadowsweet rust gall, which forms as a chemically induced swelling that emerges from the lower surface of leaves of meadowsweet (Filipendula ulmaria).
In its life cycle, the fungus grows within the petioles and midribs of meadowsweet (Filipendula ulmaria), a perennial plant in the rose family. This growth causes swelling and distortion of affected plant tissue. Sori develop on the plant that carry bright orange spores. The spores of this rust fungus are carried by air movements to reach new meadowsweet plants. This rust fungus has a severe negative impact on the survival of meadowsweet seedlings.