These creeping thistles (Cirsium arvense) have been infected by a form of the bacterium Pseudomonas syringae which destroys the chlorophyll. Often the whitened plants only occur in small groups or singly and are not as universal as they are in this field.
Uploaded to Geograph by Patrick Roper on 6 September 2004
Photo © Patrick Roper, 6 September 2004. Licensed for reuse under this Creative Commons licence