Meadowsweet rust gall Meadowsweet rust gall Triphragmium ulmariae is a species of fungus in the Sphaerophragmiaceae family. It causes meadowsweet rust gall, which develops as a chemically induced swelling, arising from the lower surface of the meadowsweet leaves. This common gall is caused by the foliar 'rust' fungus "Triphragmium ulmariae" (DC.) Link, 1825 . The fungus attacks the petioles and / or midribs of the perennial meadowsweet ("Filipendula ulmaria") plant, a member of the family Rosaceae, causing swelling and distortion. Sori develop with bright orange spores. The rust's spores reach the meadowsweet via air movements and are spread from the galls that develop
Rust Rust Rust is an iron oxide, a usually red oxide formed by the redox reaction of iron and oxygen in the presence of water or air moisture. Several forms of rust are distinguishable both visually and by spectroscopy, and form under different circumstances. Rust consists of hydrated iron(III) oxides FeO·"n"HO and iron(III) oxide-hydroxide (FeO(OH), Fe(OH)). Given sufficient time, oxygen, and water, any iron mass will eventually convert entirely to rust and disintegrate. Surface rust is flaky and friable, and it provides no protection to the underlying iron, unlike the formation of patina on copper surfaces. Rusting is the common term