Pascal Tordeux / Walnut (Juglans regia) in field of ripe barley before a storm, Ribemont, Picardy, France.

Nigel Cattlin / Walnut (Juglans regia), developing leaves , necrotic with frost damage. Berkshire, England, UK. May.

Pascal Tordeux / Walnut tree (Juglans regia) in the middle of a wheat field, Viller Le Sec, Picardy, France. August

Stephen Dalton / Walnut tree (Juglans regia) in full summer leaf, Sussex, UK

Martin Gabriel / Walnut (Juglans regia) fruits, Bavaria, Germany, July

Eric Baccega / Harvest of Common walnuts (Juglans regia), Alsace, France, September.

Eric Baccega / Harvest of Common walnuts (Juglans regia), Alsace, France, September.

Eric Baccega / Harvest of Common walnuts (Juglans regia), Alsace, France, September.

Juan Manuel Borrero / Illustration of Walnut tree (Juglans regia). Detail of leaves and fruit. Pencil and watercolor painting.

Juan Manuel Borrero / Walnut tree (Juglans regia) Miralles Mountain Range, Barclelona province, Spain, April

David Woodfall / Basket of walnuts (Jugulans regia) collected in traditional peasant community, grown as cash crop. Romania, October 2010

Artur Tabor / Walnut (Juglans regia) fruit on tree, Poland

Philippe Clement / Common walnuts (Juglans regia) with seed exposed inside shell, native to Southern Europe and Asia

Philippe Clement / Common walnut (Juglans regia), native to Southern Europe and Asia

Philippe Clement / Common walnut (Juglans regia) fruit and nut, native to Southern Europe and Asia

Philippe Clement / Common walnut (Juglans regia), native to Southern Europe and Asia

Philippe Clement / Common walnuts (Juglans regia) seed exposed in shell, native to Southern Europe and Asia

Philippe Clement / Common walnuts (Juglans regia) seed exposed in shell, native to Southern Europe and Asia

Philippe Clement / Common walnuts (Juglans regia), native to Southern Europe and Asia

Philippe Clement / Common walnuts (Juglans regia) native to Southern Europe and Asia

Philippe Clement / Common walnut (Juglans regia) kernel nut exposed in shell, native to Southern Europe and Asia

Philippe Clement / Common walnuts (Juglans regia) seed exposed in shell, native to Southern Europe and Asia

Rob Cousins / Walnuts ripening on Walnut tree (Juglans regia) Kent, UK

Nature Production / Walnuts {Juglans regia} ripening on tree, Japan

Nature Production / Walnuts {Juglans regia var. orientis} Nagano, Japan

Nature Production / Fruit of various walnut species {Juglans ailantifolia} (left), {Pterocarya rhoifolia}(middle), and {Juglans regia var. orientis} (right) Japan

Nature Production / Walnut {Juglans regia var. orientis} Japan

Philippe Clement / Close-up of bark of Walnut tree {Juglans regia} Belgium

Gerry Ellis / English Black Walnut (Juglans regia) grove in northern central California, native to Europe

Thomas Marent / English Black Walnut (Juglans regia) tree, Zug, Switzerland

Thomas Marent / English Black Walnut (Juglans regia) trees, Zug, Switzerland

Nigel Cattlin / Walnuts (Juglans regia) maturing green fruit on tree, Berkshire, UK. July.

Juergen & Christine Sohns / English Black Walnut (Juglans regia) nuts, Germany

Nigel Cattlin / Walnut leaf gall mite (Aceria erinea) white blisters of mites on the lower surface of a walnut tree (Juglans regia) leaf, Berkshire, England, UK, June

Nigel Cattlin / Walnut leaf gall mite (Aceria erinea) blisters on the upper surface of a walnut tree (Juglans regia) leaf, Berkshire, England, UK, June

Nigel Cattlin / Walnut leaf gall mite (Aceria erinea) blisters on the upper surface of a walnut tree (Juglans regia) leaf, Berkshire, England, UK, June

Nigel Cattlin / Young fruit from female flowers on a walnut tree (Juglans regia) with young leaves in spring, Berkshire, England, UK, May

Nigel Cattlin / Young fruit from female flowers on a walnut tree (Juglans regia) with young leaves in spring, Berkshire, England, UK, May

Nigel Cattlin / Male catkins on a walnut tree (Juglans regia) with young leaves in spring, Berkshire, England, UK, May

Nigel Cattlin / Male catkins on a walnut tree (Juglans regia) with young leaves in spring, Berkshire, England, UK, May

Linda Pitkin / Walnut (Juglans regia), catkins and young foliage, at edge of field, Surrey, England, May.