SUMMARYThe cause of a previously undocumented leaf mottling ofSpartinaspecies was investigated. Negatively stained preparations of sap from mottled leaves revealed flexuous particles 725 × 12 nm. Pinwheels with associated laminar inclusion bodies were observed in thin sections of affected mesophyll cells. The virus was purified from infectedSpartina anglicaplants and had a sedimentation coefficient in 0·015mborate of 150S.The virus was transmitted by inoculation of sap to healthySpartina anglica, but not to a range of other graminaceous or dicotyledonous species tested. It was distantly serologically related to agropyron mosaic virus, but not to other viruses with similar morphology; the name spartina mottle virus is propose