Claudio Contreras / Aerial view of Red mangrove (Rhizophora mangle) coastal lagoon, Sian Ka'an Biosphere Reserve, Caribbean Sea, Mexico, January

Claudio Contreras / Red mangrove (Rhizophora mangle) in sinkhole, Casa Cenote, near Tulum, Yucatan Peninsula, Mexico, April

Philippe Clement / Long-spurred violet (Viola calcarata) in flower, Val Veny, Italian Alps, Italy, June

Sven Zacek / Misty lake, with trees reflected in the water, and Willow (Salix) trees silhouetted on the shore, Suur Emajogi river, Tartumaa, Estonia, May 2014.

Pascal Pittorino / Horned pansy (Viola cornuta) in botanic garden, Var, France, March.

Gabriel Rojo / Close up of Passionflower (Passiflora caerulea) La Pampa, Argentina.

Alex Hyde / Peacock butterfly (Inachis io) feeding on Goat Willow catkins (Salix caprea), an important food source for pollinators in early spring. Peak District National Park, UK. April.

Pascal Tordeux / Avenue of Poplar (Populus sp) trees in fog, Villers Le Sec, Aisne, Picardy, France, December.

Ole Jorgen Liodden / Heartsease / Wild pansy (Viola tricolor) flower, Norway, May.

Nick Upton / Eurasian beaver (Castor fiber) gnawing the trunk of a Willow tree (Salix sp.) in woodland enclosure at night. Devon Beaver Project, run by Devon Wildlife Trust, Devon, UK, April. Taken by a remote cam...

Jack Dykinga / Road winding through aspen trees (Populus tremuloides) in autumn, Dixie National Forest, Boulder Mountain, Utah. October 2013.

Jack Dykinga / Cottonwood (Populus fremontii) in autumn, Long Canyon, Grand Staircase-Escalante National Monument, Utah, USA. October 2013.