Gary K. Smith / Rows of Lettuce (Lactuca sativa) and salad vegetables, Eden Project, Cornwall, England, UK, May

Nick Turner / Lettuce (Lactuca sativa) close up of seedlings growing in a vegetable bed, UK, June.

Gary K. Smith / Close up of Red Lettuce (Lactuca sativa) 'Dazzle' variety. Norfolk, England, June.

Ernie Janes / Rows of Lettuces (Lactuca sp) in field, Norfolk, UK

Ernie Janes / Rows of Lettuces (Lactuca sp) vegetable garden, Norfolk, UK

Ernie Janes / Rows of Lettuces (Lactuca sp) vegetable garden, Norfolk, UK

Gary K. Smith / Lettuce (Lactuca sativa) plants protected with wire netting against bird damage. Norfolk, England, May.

Jerry Monkman / A field of organic Lettuce plants (Lactuca sativa) growing at Harlow Farm in Westminster, Vermont, USA. August 2007

Jerry Monkman / A field of organic Lettuce plants (Lactuca sativa) growing at Harlow Farm in Westminster, Vermont, USA. August 2007

Philippe Clement / Lettuce (Lactuca sativa) in field, Belgium

Philippe Clement / Lettuce (Lactuca sativa) in field, Belgium

Juan Manuel Borrero / Field of lettuces (Lactuca sativa) near Tordera river, Barcelona, Catalonia, Spain. March 2008.