Puccinia urticata s.lat. is a rust fungus which causes galls on the stems, petioles and leaves of the alternate host, nettles (Urtica dioica and Urtica urens). The galls are reddish and can be large, causing considerable swelling and distortion of stem and petioles.  Orange aecia and spermogonia are borne on the swollen areas and leaf undersides. 

The uredinial and telial stages are on the primary plant host, a sedge, and do not cause galls.  Due to small morphological differences in the telial stage, and the range of sedge species used as primary hosts, it is cosidered by some sources to be a complex of species; other sources consider these are varieties.   The various species or varieties cannot be identified from the aecial host, nettle.

Nettle Sedge

Photograph the rust on the Nettle host.  Ensure you have noted the host-plant species in your comments.   If recording on a sedge, microscopic examination may be needed.

Alternate aecial host on nettles; primary host on sedges

See species page on the 'Plant Parastites of Europe' website

These are the species and the uredinial/telial sedge hosts within the species complex:

• Puccinia urticae-acutae - Carex acuta, elata, nigra.
• Puccinia urticae-flaccae - Carex flacca
• Puccinia urticae-hirtae - Carex hirta
• Puccinia urticae-inflatae - Carex rostrata
• Puccinia urticae-paniceae - Carex panicea
• Puccinia urticae-ripariae - Carex riparia
• Puccinia urticae-vesicariae - Carex vesicaria