Nick Turner / Ancient Sweet Chestnut tree {Castanea sativa} Tortworth, Gloucestershire, England, UK, - believed to be up to 1200 years old.

Simon Colmer / Sweet chestnut (Catanea sativa) buds in winter, UK

Simon Colmer / Horse chestnut (Aesculus hippocastanum) bud in winter, UK

GEORGETTE DOUWMA / Grey squirrel {Sciurus carolinensis} damage to Horse chestnut tree {Aesculus hippocastanum} Regent's Park, London, Britain. Amorous males try to impress females by stripping bark off trees.

Brian Lightfoot / Horse chestnut fallen seeds (Aesculus hippocastanum) UK Conkers

Juan Manuel Borrero / Sweet chestnuts {Castanea sativa} Las Medulas NP, Leon, Spain

Juan Manuel Borrero / Sweet chestnut tree {Castanea sativa} Las Medulas National Park, Leon, Spain

Juan Manuel Borrero / La Cuevona cave. Roman gold mine. Las Medulas National Park, Leon, Spain

Mark Taylor / Horse chestnut tree {Aesculus hippocastanum} in bloom in fields with buttercups Surrey, UK.

Philippe Clement / Sweet chestnuts {Castanea sativa} Belgium

Jason Smalley / Horse chestnut leaves above stream {Aesculus hippocastanum} England

Jason Smalley / Horse chestnut tree in flower {Aesculus hippocastanum} England

Philippe Clement / Close up of bark of Sweet chestnut tree {Castanea sativa} Belgium

GEORGETTE DOUWMA / Horse chestnut conkers {Aesculus hippocastanum} UK

GEORGETTE DOUWMA / Horse chestnut conkers {Aesculus hippocastanum} England

Brian Lightfoot / Horse chestnut conkers, fallen seeds (Aesculus hippocastanum) UK.

Philippe Clement / Sweet chestnuts {Castanea sativa} Belgium

Artur Tabor / Horse chestnut nuts /conkers (Aesculus hippocastanum) Poland, Europe

Will Watson / Ancient Sweet chestnut tree {Castanea sativa} with limited new growth, UK

Ross Hoddinott / Horse chestnut tree sticky buds {Aesculus hippocastanum} Cornwall, UK

Colin Varndell / Sweet chestnut tree {Castanea sativa} in field of Linseed in flower. UK

WILLIAM OSBORN / Horse chestnut conkers ready to fall from tree {Aesculus hippocastanum} UK

Ross Hoddinott / Horse chestnut tree leaves emerging {Aesculus hippocastanum} Cornwall, UK

Jose B. Ruiz / Sweet chestnut branches + fruit (Castanea sativa) Asturias Spain Muniellos Biological Reserve

Brian Lightfoot / Horse chestnut tree in flower (Aesculus hippocastanum) Scotland

Artur Tabor / Horse chestnut (Aesculus hippocastanum) ripe seeds (conkers). Poland, Europe

Christoph Becker / Horse chestnut (Aesculus hippocastanum) leaves in spring, Germany

Duncan Mcewan / Horse chestnut (Aesculus hippocastanum) opening buds. Sequence 2/2. UK, Europe

Duncan Mcewan / Horse chestnut (Aesculus hippocastanum) opening buds. Sequence 1/2. UK, Europe

Duncan Mcewan / Horse chestnut opening buds (Aesculus hippocastanum) UK

John Downer / Horse chestnut leaves (Aesculus hippocastanum) in autumn. England, UK, Europe

Niall Benvie / Horse chestnut tree leaves emerging from bud. Latvia

Niall Benvie / Conkers and Horse chestnut leaf (Aesculus hippocastanum), autumn. Scotland, UK, Europe

Niall Benvie / Horse chestnut buds bursting into leaf, Scotland, UK, Europe

Jose B. Ruiz / Sweet chestnut branches + fruit (Castanea sativa). Muniellos Biological Reserve, Asturias, Spain, Europe

Jose B. Ruiz / Horse chestnut (Aesculus hippocastanum) in flower, Spain Alicante

Brian Lightfoot / Horse chestnut tree flowers (Aesculus hippocastanum) Scotland

John Downer / Horse chestnut leaves (Aesculus hippocastanum) in autumn. England, England, UK, Europe

Mike Read / Path through woodland with Sweet chestnut trees (Castanea sativa), Backley Inclosure, New Forest National Park, Hampshire, UK, October 2010

Mike Read / Sweet chestnut (Castanaea sativa) trees in autumn mist, Backley Inclosure, New Forest National Park, Hampshire, UK, October

Ingo Arndt / Buttress roots of chestnut tree, Christmas Island, Indian Ocean, Territory of Australia

Fabio Liverani / Autumn trees in the Foreste Casentinesi, Monte Falterona, Campigna: a millenary forest in the Apennines of Tuscany and Romagna, Italy

Niall Benvie / Horse chestnut tree flower {Aesculus hippocastanum} Scotland, UK

WILLIAM OSBORN / Horse Chestnut tree flower {Aesculus hippocastanum} UK

WILLIAM OSBORN / Horse chestnut tree {Aesculus hippocastanum} Autumn UK

Duncan Mcewan / Horse chestnut tree leaf scar + buds (Aesculus hippocastanum) UK

Artur Tabor / Horse chestnut unripe seeds (Aesculus hippocastanum) UK Conkers

Niall Benvie / Close up of horse chestnut tree bark {Aesculus hippocastanum} Scotland

Pete Oxford / African star chestnut fruit {Sterculia africana} Kubu Is, Botswana Makgadikgadi

Duncan Mcewan / Horse chestnut leaves emerging {Aesculus hippocastanum} Scotland, UK Perthshire

GEORGETTE DOUWMA / Horse chestnut fruit / conkers {Aesculus hippocastanum} UK

George McCarthy / Sweet chestnut coppiced trees {Castanea sativa} Kent UK