Rust - Nettle Cluster Cup Puccinia urticata
Habitat
Description Puccinia urticata is a characteristic rust fungus devloping on the stems and leaves of Common (Stinging) Nettle or Small (Annual) Nettle. It starts as small orange blisters or swellings. Close examination may reveal the pinhead-like fruiting bodies of the fungus.
Life history Spores may spread to other nettles or to various sedges where the telial stage of the lifecycle continues without causing a gall to form.