An art project at Wimbledon:

The artists essentially use grass as a form of photographic paper, projecting a black-and-white negative image onto a patch of grass as it grows in a dark room, and using the natural photosensitive properties of the grass to reproduce photographs.

The best part:

Part of what interests Ackroyd and Harvey about using grass is its ephemeral qualities, with the images they create often melting away soon after the grass is exposed to natural light and begins to grow. In galleries the artists have used light control to prolong the life of a work, but, before you rush to SW19 to see the HSBC piece for yourselves, this work lasted only as long as the Wimbledon crowds, and now that we have settled into the final stages of the competition has already pretty much disappeared.