Jack Dykinga / Bark patterns of Aspen tree (Populus tremula) in front of a Ponderosa pine (Pinus ponderosa) trunk, Kaibab National Forest, Arizona, USA

Grzegorz Lesniewski / Riparian forest with Crack Willow (Salix fragilis), White Willow (Salix alba) and blooming Wild Cherry (Prunus avium). Bieszczady Mountains, the Carpathians, Poland, May.

Guy Edwardes / 2020VISION / Pussy willow catkins (Salix caprea), Somerset Levels, Somerset, England, UK, April

Guy Edwardes / 2020VISION / Pussy willow catkin (Salix caprea) bursting out from bud, Somerset Levels, Somerset, England, UK, April

Daniel Heuclin / Rio Grande Cottonwood tree (Populus fremonti wislizenii) on a sand "pedestal" White Sands National Park. New-Mexico, USA, August 2009

Floris van Breugel / Autumn colours of Aspen tree (Populus tremula) Sierra Nevada, California, USA. September 2009

John Cancalosi / Osier stems (Salix viminalis) covered in hoar frost, Warwickshire, England, UK

Wild Wonders of Europe / della Ferrera / Trees, mainly White willow (Salix alba) in flooded karst plateau, Livanjsko Polje, Bosnia and Herzegovina, May 2009

Wild Wonders of Europe / della Ferrera / Photographer, Elio della Ferrera, holding camera sitting on fallen tree, in an oxbow of the Sava river flooded area, Lonjsko Polje Nature Park, on the Croatia Bosnia and Herzegovina border, June 2009

Wild Wonders of Europe / della Ferrera / Flooded trees, mainly White willow (Salix alba) Livanjsko Polje (karst plateau) Bosnia and Herzegovinam May 2009

Wild Wonders of Europe / della Ferrera / Trees, mainly White willow (Salix alba) in flooded karst plateau, Livanjsko Polje, Bosnia and Herzegovina, May 2009

Laurie Campbell / Looking up the trunk of an Aspen tree (Populus tremula) in autumn, Speyside, Scotland, UK, October

Wild Wonders of Europe / Bergmann / Woolly willow (Salix lanata) growing by Selfoss waterfall, Jokulsargljufur National Park, Thingeyjarsyslur, Iceland, July 2009

Wild Wonders of Europe / Bergman / Dwarf willow (Salix herbacea) and flowering plant, Thingeyjarsyslur, Iceland, June 2009 Licensed for exclusive book cover until 1 February 2015.

Jack Dykinga / Havasu Falls with Fremont cottonwood trees (Populus fremontii) Havasupai Reservation, Arizona, USA

Jack Dykinga / Havasu Falls cascade behind Fremont cottonwood trees (Populus fremontii) glowing in reflected canyon light, Havasupai Reservation, Arizona, USA

Wild Wonders of Europe / Radisics / Willow trees (Salix) growing in water, Lake Skadar, Lake Skadar National Park, Montenegro, May 2008

Jack Dykinga / Havasu Falls with travertine formations in the river creating spillways, and Fremont cottonwood trees (Populus fremontii), dawn, Havasupai Reservation, Arizona, USA

Wild Wonders of Europe / Zacek / Aspen tree (Populus tremula) trunk with a line of snow on it, Oulu, Finland, February 2009

Ross Hoddinott / Pussy willow / Sallow (Salix caprea) catkins, Cornwall, UK. April .

Shattil & Rozinski / Quaking aspen tree (Populus tremuloides) leaves and twigs coated with ice, over stream, Southern Colorado, USA, October

Shattil & Rozinski / Quaking aspen trees (Populus tremuloides) in autum, San Luis Valley, Colorado, USA

Shattil & Rozinski / Quaking aspen trees (Aspen tremuloides) in autumn, San Luis Valley, Colorado, USA

Donald M. Jones / American Elk (Cervus elaphus nelsoni) bull with aspens, western Alberta, Canada

Donald M. Jones / American Beaver (Castor canadensis) swimming with willow branch in mouth, western Montana

Simon Colmer / Goat willow (Salix caprea) twig and opening buds in winter, UK

Shattil & Rozinski / Fallen Aspen leaves {Populus tremula} on rocks in river in autumn, USA

Shattil & Rozinski / Aspen tree {Populus tremula} leaves and trunks in autumn, USA

Shattil & Rozinski / Swirling leaves of Aspen tree {Populus tremula} floating on water surface in autumn, USA

Shattil & Rozinski / Swirling leaves of Aspen tree {Populus tremula} floating on water surface in autumn, USA

Tim Fitzharris / Aspen and Spruce trees dusted with snow, Rocky Mountain National Park, Colorado

Tim Fitzharris / Aspens at Independence Pass, Colorado

Ross Hoddinott / Sallow / Pussy willow {Salix caprea} catkin, Cornwall. UK

Tim Fitzharris / Quaking Aspen (Populus tremuloides) grove in fall colors, Maroon Bells, Snowmass Wilderness, Colorado

Simon Colmer / Goat willow (Salix caprea) opening buds in spring, UK

Simon Colmer / Osier (Salix viminalis) buds in winter, UK

Tim Fitzharris / Cottonwood (Populus sp) trees in autumn, Teec Nos Pos, Arizona

Michael Quinton / Common Porcupine (Erethizon dorsatum) feeding on Pussy Willow (Salix discolor) in spring, Alaska

Michael Quinton / Common Porcupine (Erethizon dorsatum) feeding on Pussy Willow (Salix discolor) in spring, Alaska

Michael Quinton / Snowshoe Hare (Lepus americanus) feeding on Pussy Willow (Salix discolor) in winter, Alaska

Michael Quinton / Snowshoe Hare (Lepus americanus) feeding on Pussy Willow (Salix discolor) branch in winter, Alaska

Mark Hamblin / 2020VISION / Wetland landscape with Willow (Salix) tree in the background, Woodwalton Fen National Nature Reserve, Cambridgeshire, England, UK, July 2012.

Wild Wonders of Europe / Widstrand / White Poplar trees (Populus alba) with sunlight from behind, Letea forest, Strictly protected nature reserve, Danube delta rewilding area, Romania

Wild Wonders of Europe / Widstrand / White Poplar trees (Populus alba) Letea forest, Strictly protected nature reserve, Danube delta rewilding area, Romania

Wild Wonders of Europe / Widstrand / White Poplar trees (Populus alba) Letea forest, Strictly protected nature reserve, Danube delta rewilding area, Romania

Tim Fitzharris / Quaking Aspen (Populus tremuloides) forest, Marcellina Mountain, Raggeds Wilderness, Colorado

Tim Fitzharris / Quaking Aspen (Populus tremuloides) trees, Crested Butte, Colorado

Tim Fitzharris / Quaking Aspen (Populus tremuloides) forest and Mount Sneffels, San Juan Mountains, Colorado

Tim Fitzharris / Quaking Aspen (Populus tremuloides) in autumn, White River National Forest, Colorado

Tim Fitzharris / Quaking Aspen (Populus tremuloides) forest in autumn, Snowmass Mountain near Quaking Aspen, Colorado

Tim Fitzharris / Quaking Aspen (Populus tremuloides) forest in autumn, Marcellina Mountain, Raggeds Wilderness, Colorado

Tim Fitzharris / Quaking Aspen (Populus tremuloides) trees and Highland Peak, Colorado

Floris van Breugel / Aspen leaves on an early snow, North Fork of Bishop Creek, near Bishop, Eastern Sierra, California, USA, October.

Floris van Breugel / Aspen (Populus tremula) trees in autumn colours, North Fork of Bishop Creek, near Bishop, Eastern Sierra, California, USA

Colin Monteath / Willow (Salix sp) trees reflected in Kelland Ponds, Mackenzie Country, Canterbury, New Zealand

David Woodfall / Black poplar tree (Populus nigra) by a housing development on a flood plain, Glasdir, Ruthin, Vale of Clwyd, Denbighshire, Wales. November 2012.

Will Watson / Reflections of Grey willow (Salix cinerea) and Alder (Alnus glutinosa) trees, with exposed dead wood in a glacial kettle hole pond, Herefordshire, England, UK, Europe, November

Will Watson / Reflections of Grey willow (Salix cinerea) and Alder (Alnus glutinosa) trees, with exposed dead wood in a glacial kettle hole pond, Herefordshire, England, UK, Europe, November

Will Watson / Natural oxidation in a pond with sloughed periphyton, pollen and Pussy willow (Salix caprea) catkins, Herefordshire, England, UK, March

Will Watson / Reflections of Grey willow (Salix cinerea) and Alder (Alnus glutinosa) trees, with exposed dead wood in a glacial kettle hole pond, Herefordshire, England, UK, Europe, November

Will Watson / Natural oxidation in a pond with sloughed periphyton, pollen and Pussy willow (Salix caprea) catkins, Herefordshire, England, UK, March

Tim Fitzharris / Cottonwood (Populus sp) trees in autumn, Carson Valley, Nevada

Tim Fitzharris / Cottonwood (Populus sp) trees in autumn near Maroon Bells, Colorado

Terry Whittaker / 2020VISION / Willow (Salix fragilis) seed dispersal, Rutland Water, Rutland, England, UK, April. 2020VISION Book Plate.

Jim Brandenburg / Cottonwood (Populus sp) tree in prairie

Ernie Janes / Greenfinch (Carduelis chloris) perched amongst Pussy willow catkins (Salix caprea) UK, March.

Ernie Janes / Greenfinch (Carduelis chloris) perched amongst Pussy willow catkins (Salix caprea) UK, March.

Ernie Janes / Goldfinch (Carduelis carduelis) perched amongst willow catkins (Salix caprea) UK, March.

Ernie Janes / Goat / Pussy willow (Salix caprea) catkins growing in hedgerow, UK, March.

Ernie Janes / Chaffinch (Fringilla coelebs) male perched in Willow tree with catkins (Salix caprea) UK, March.

Colin Varndell / Grey willow tree (Salix cinerea) male catkin inflorescence, UK, March

Colin Varndell / Grey willow tree (Salix cinerea) female catkin inflorescence releasing seeds, UK, May

Wild Wonders of Europe / Möllers / Willows (Salix sp) and other vegetation at the bank of the San River, Myczkowce, Poland, September 2011

Wild Wonders of Europe / Möllers / Willows (Salix sp) and other vegetation on the bank of the San River, Myczkowce, Poland, September 2011

Wild Wonders of Europe / Möllers / Polish tied fly patterns imitating duns / adults of the Blue-winged olive mayfly displayed on Willow (Salix sp) leaves, Myczkowce, San River, Poland, September 2011

Wild Wonders of Europe / Möllers / Polish tied fly patterns imitating various Gammarus species displyed on a Willow (Salix sp) branch cut by a Eurasian beaver (Castor fiber) Myczkowce, San River, Poland,

Colin Varndell / Female Grey willow tree (Salix cinerea) catkins, Dorset, UK, April

Colin Varndell / Female Grey willow tree (Salix cinerea) catkins, Dorset, UK, April

George Sanker / Aspen trees (Populus tremula) in Grand Teton NP, Wyoming, USA, October 2009

Erlend Haarberg / Net-leaved willow (Salix reticulata) growing over moss, Norway, July

Erlend Haarberg / Willow (Salix sp) low growing in a barren landscape, Iceland, June 2008

George Sanker / Cottonwood trees (Populus sargentii) on the Lamar River, Yellowstone National Park, Wyoming, USA, October 2011

Konstantin Mikhailov / Water in upland plateau with tundra-like thickets of Birch and dwarf Willows, and thin forest of White spruce (Picea glauca) with Alaska Range in the distance, Denali Highway, Alaska, USA, September 2...

Laurie Campbell / Goat / Pussy willow / Sallow (Salix caprea) flowers in spring, Midlothian, Scotland, April

Laurie Campbell / Dwarf / Least willow tree (Salix herbacea) growing between crack in boulder, Isle of Rum National Nature Reserve, Hebrides, Scotland, June

Laurie Campbell / Aspen tree (Populus tremula) in autumn, Speyside, Scotland, October

Donald M. Jones / Elk (Cervus elaphus) antler scrape on Cottonwood (Populus sp) trunk, Jasper National Park, Alberta, Canada

Donald M. Jones / Elk (Cervus elaphus) antler scrape on Cottonwood (Populus sp) trunk, Jasper National Park, Alberta, Canada

Donald M. Jones / Elk (Cervus elaphus) bull bugling, Jasper National Park, Alberta, Canada

Donald M. Jones / Elk (Cervus elaphus) bull bugling, Jasper National Park, Alberta, Canada

Donald M. Jones / Elk (Cervus elaphus) bull with females in forest, Jasper National Park, Alberta, Canada

Peter Cairns / 2020VISION / Willow tree (salix sp.) backlit in spring, Glen Affric, Scotland, UK, May

Simon Colmer / Pussy willow (Salix caprea) with female catkins in spring, Eridge Rocks SSSI, Sussex, UK

Mark Hamblin / 2020VISION / Aspen trees (Populus tremula) in autumn, Strathspey, Cairngorms NP, Scotland, UK, September 2011

Michael Quinton / Red Squirrel (Tamiasciurus hudsonicus) feeding on willow catkins, Alaska

Philippe Clement / Grass covered in seed fluff from female willow (Salix sp.) tree catkins, dispersed by the wind. Belgium, May.