Alex Hyde / Salicine (Molecular Formula C17H20N2O) an antique microscope slide, photographed under cross polarised light. In ancient times, salicine-containing plants such as willow (Salix sp.) were used for pain...

Richard Du Toit / Outeniqua yellowwood (Afrocarpus falcatus) trees, Western Cape Province, South Africa.

Richard Du Toit / Cape sugarbird (Promerops cafer) perched on Common sugarbush (Protea repens) flower, Swartberg Pass, Western Cape Province, South Africa.

Richard Du Toit / Greater doublecollared sunbird (Nectarinia afra) perched among Pincushion (Leucospermum sp.) flowers, Garden Route, Western Cape Province, South Africa.

Richard Du Toit / Common milkweed locust (Phymateus morbillosus) resting on Pincushion (Leucospermum sp.) flower, Western Cape Province, South Africa.

Richard Du Toit / Cape weaver (Ploceus capensis) perched on flower (Strelitzia sp.), Garden Route, Western Cape Province, South Africa.

Richard Du Toit / Amethyst sunbird (Chalcomitra amethystina) perched on Pincushion (Leucospermum sp.) flower, Garden Route, Western Cape Province, South Africa.

Richard Du Toit / Amethyst sunbird (Chalcomitra amethystina) perched on Pincushion (Leucospermum sp.) flower, Garden Route, Western Cape Province, South Africa.

Ernie Janes / Cardoon thistle (Cynara cardunculus) in flower, Norfolk, UK. July.

Ernie Janes / Old coppiced Beech (Fagus sp.) trees in woodland, Low Scrubs, Coombe Hill, Buckinghamshire, UK. April.

Ernie Janes / Old coppiced Beech (Fagus sp.) trees in woodland, Low Scrubs, Coombe Hill, Buckinghamshire, UK. April.

Ernie Janes / Globe artichoke / Cardoon thistle (Cynara cardunculus) in flower, Norfolk, UK. July.

Ernie Janes / Bluebells (Hyacinthoides non-scripta) in flower in woodland and along footpath, Ashridge, Hertfordshire, UK. May.

Ernie Janes / Bluebells (Hyacinthoides non-scripta) in flower in woodland, Ashridge, Hertfordshire, UK. May.

Jack Dykinga / Aspen trees (Populus tremuloides) at sunset on the slopes of Escudilla Mountain, Apache Sitgreaves National Forest, Arizona, USA.

Jack Dykinga / Water lilies (Nymphaea sp.) in flower in marshland pool, San Luis Potosi, Mexico.

Jack Dykinga / Yucca (Yucca carnerosana) in flower with fog-shrouded Loquat leaf oak trees (Quercus rysophylla) draped with Spanish moss (Tillandsia usneoides), Tamaulipas, Sierra Tamaulipas, Mexico.

Jack Dykinga / Garambullo (Myrtillocactus geometrizans) in flower with Pitaya (Stenocereus griseus) and Creosote (Larrea tridentata), Chihuahuan Desert near Tula, Tamaulipas, Mexico.

Jack Dykinga / Agave (Agave americana protoamericana) in a forest of Oak trees, Sierra Madre Oriental, Tamaulipas, Mexico.

Jack Dykinga / Agave (Agave americana protoamericana) in a forest of Oak trees, Sierra Madre Oriental, Tamaulipas, Mexico.

Jack Dykinga / Cow parsnip (Heracleum lanatum) in flower with fog rising at sunrise over Absaroka Mountain range, Lamar Valley near Soda Butte Creek, Yellowstone National Park, Wyoming, USA.

Jack Dykinga / Manzanita (Arctostaphylos pungens) in flower surrounding a Century plant (Agave parryi) with Alligator juniper (Juniperus deppeana) cones in leaf rosette, Diamond Point, Tonto National Forest, Arizona...

Jack Dykinga / Diamond Point at sunset with Century plants (Agave parryi) and Desert ceanothus (Ceanothus greggii) in chapparal plant community, Diamond Point, Tonto National Forest, Arizona, USA.

Jack Dykinga / Alligator juniper (Juniperus deppeana) with twisted trunk in evening light, Sycamore Canyon, Kaibab National Forest, Arizona, USA.

Jack Dykinga / Sunflowers (Helianthella quinquenervis) in flower in meadow near Sunset Crater with Ponderosa pines (Pinus ponderosa) in background, Coconino National Forest, Arizona, USA.

Jack Dykinga / Sycamore (Acer pseudoplatanus) tree rooted in rocky streambed. Sycamore Canyon, Arizona, USA.

Jack Dykinga / Aspen trees (Populus tremuloides) in autumnal colours on the slopes of Escudilla Mountain, Apache Sitgreaves National Forest, Arizona, USA.

Jack Dykinga / Aspen (Populus tremuloides) leaves and Ponderosa pine (Pinus ponderosa) cones floating in water after rain, Apache-Sitgreaves National Forest, Arizona, USA.

Jack Dykinga / Sunflowers (Helianthus sp.) in flower at dawn in Bonito Park with San Francisco mountain peaks in background, Coconino National Forest, Arizona, USA.

Jack Dykinga / Aspen (Populus tremuloides) and Birch (Betula sp.) trees in autumn colour reflecting in Talbot Lake beneath the Miette Range, Jasper Provincial Park, Alberta, Canada. September.

Jack Dykinga / Aspen (Populus tremuloides) trees bearing the marks of antlers amid golden fall coloured forest, Banff Forest, Alberta, Canada. September.

Jack Dykinga / Autumn coloured Aspen (Populus tremuloides) and Birch (Betula sp.) leaves among White fir (Abies amabilis) cones on the forest floor, Figure Eight lake Provincial Park, Alberta, Canada. September.

Jack Dykinga / Aspen (Populus tremuloides) and Birch (Betula sp.) trees in autumn colour reflecting in Talbot Lake beneath the Miette Range, Jasper Provincial Park, Alberta, Canada. September.

Marie Read / Varied thrush (Ixoreus naevius) male, perched on Spruce (Picea sp.) branch with pink cone buds, Eagle River, Alaska, USA. May.

Marie Read / Varied thrush (Ixoreus naevius) male, perched on Spruce (Picea sp.) branch with pink cone buds, singing, Eagle River, Alaska, USA. May.

Marie Read / Snow buntings (Plectrophenax nivalis) large flock in flight with American beech (Fagus grandifolia) saplings behind, Vermont, USA. January.

Marie Read / Pine grosbeak (Pinicola enucleator) male, perched on branch feeding on Ash (Fraxinus sp.) seeds in winter, Burlington, Vermont, USA. February.

Marie Read / Pine grosbeak (Pinicola enucleator) male, feeding on Spruce (Picea sp.) buds in late winter, Burlington, Vermont, USA. February.

Marie Read / Pacific wren (Troglodytes pacificus) Bering Sea race, male, perched on Cow parsnip (Heracleum maximum) singing, St. Paul, Pribilof Islands, Alaska, USA. July.

Marie Read / Northern parula (Parula americana) male in breeding plumage, singing while perched on flowering Eastern redbud (Cercis canadensis) in spring, Ohio, USA. April.

Marie Read / Northern parula (Parula americana) male in breeding plumage, perched on flowering Eastern redbud (Cercis canadensis) in spring, Ohio, USA. April.

Marie Read / Bobolink (Dolichonyx oryzivorus) male, in flight over Dandelion (Taraxacum sp.) flowers in a meadow, New York, USA. May.

Doug Perrine / Haleakala silversword / Ahinahina (Argyroxiphium sandwicense macrocephalum) in bloom at night with stars visible in the sky above, Haleakala National Park, Maui, Hawaii. Critically endangered.

Doug Perrine / Mauna Kea silversword / Ahinahina (Argyroxiphium sandwicense sandwicense) in flower on slopes of MaunaKea volcano at sunset, Big Island, Hawaii. Critically endangered.

Doug Perrine / Mauna Kea silversword / Ahinahina (Argyroxiphium sandwicense sandwicense) in flower on slopes of MaunaKea volcano at sunset, Big Island, Hawaii. Critically endangered.

Doug Perrine / Mauna Kea silversword / Ahinahina (Argyroxiphium sandwicense sandwicense) in flower, close up of blossom, MaunaKea volcano, Big Island, Hawaii. Critically endangered.

Doug Perrine / Mauna Kea silversword / Ahinahina (Argyroxiphium sandwicense sandwicense) in flower on the slopes of MaunaKea volcano, The Big Island, Hawaii. Critically endangered.

Pal Hermansen / Aspen (Populus tremula) tree in snow, with trunk gnawed by Beaver (Castor fiber), Follo, Viken, Norway. December.

Pal Hermansen / Common club-rushes (Schoenoplectus lacustris) reflecting on lake in morning fog, Ski, Follo, Viken, Norway. November.

Pal Hermansen / Common club-rushes (Schoenoplectus lacustris) reflecting on lake in morning fog, Ski, Follo, Viken, Norway. November.

Pal Hermansen / Rosebay willowherb (Chamaenerion angustifolium) in flower with lake and mountains in background, Gloppen, Vestland county, Norway. June.

Pal Hermansen / Oak (Quercus sp.) trees in forest, some of Norway´s biggest and oldest Oaks, Berge Nature Reserve, Hardanger, Vestland, Norway. Double exposure against the oak tree trunk.

Pal Hermansen / Maple (Acer sp.) and Ash (Fraxinus sp.) trees in spring reflecting in fjord, Vestland county, Norway. April.

Pal Hermansen / Oak (Quercus sp.) tree, one of the biggest oaks in Norway, 9,3 meters in diameter, Berge Nature Reserve, Hardanger, Vestland county, Norway. April. Double exposure.

Pal Hermansen / Beech (Fagus sylvatica) foilage in autumn, Viken, Norway. November.

Pal Hermansen / Beech (Fagus sylvatica) foilage in autumn, Viken, Norway. November.

Pal Hermansen / Swallowtail butterfly (Papilio machaon) in flight over Heather (Calluna vulgaris), Ytre Hvaler National Park, Oslo fjord, Norway. August.

Pal Hermansen / Cuckoo bumblebee (Bombus boehmicus) coated with pollen resting on Dandelion (Taraxacum officinale) flower in spring, Ski, Norway. May.

Pal Hermansen / Marsh marigolds (Caltha palustris) in flower, Ski, Norway. May.

Pal Hermansen / Green hairstreak butterfly (Callophrys rubi) taking flight from Coltsfoot (Tussilago farfara) flower, Follo, Norway. May.

Pal Hermansen / Broadleaf cattail (Typha latifolia) disintegrating fruit with spreading seeds in spring, Follo, Norway. April.

Pal Hermansen / Male fern (Dryopteris filix-mas) and Bracken (Pteridium aquilinum) KIRLIAN image, Norway.

Pal Hermansen / Common club-rushes (Schoenoplectus lacustris) along lake edge, Follo, Viken, Norway. October.

Pal Hermansen / Coltsfoot (Tussilago farfara) KIRLIAN image, Norway.

Jack Dykinga / Aurora Borealis, the strongest in 20 years, lighting up the Sonoran desert, silhouetting Saguaro cacti (Carnegiea gigantea) against the colourful night sky, BLM land northwest of Tucson, Sonoran deser...

Jack Dykinga / Aurora Borealis, the strongest in 20 years, lighting up the Sonoran desert, silhouetting Saguaro cacti (Carnegiea gigantea) against the colourful night sky, BLM land northwest of Tucson, Sonoran deser...

Jack Dykinga / Aurora Borealis, the strongest in 20 years, lighting up the Sonoran desert, silhouetting Saguaro cacti (Carnegiea gigantea) against the colourful night sky, BLM land northwest of Tucson, Sonoran deser...

Jack Dykinga / Aurora Borealis, the strongest in 20 years, lighting up the Sonoran desert, silhouetting Saguaro cacti (Carnegiea gigantea) against the colourful night sky, BLM land northwest of Tucson, Sonoran deser...

Jack Dykinga / Aurora Borealis, the strongest in 20 years, lighting up the Sonoran desert, silhouetting Saguaro cacti (Carnegiea gigantea) against the colourful night sky, BLM land northwest of Tucson, Sonoran deser...

Jack Dykinga / Aurora Borealis, the strongest in 20 years, lighting up the Sonoran desert, silhouetting Saguaro cacti (Carnegiea gigantea) against the colourful night sky, BLM land northwest of Tucson, Sonoran deser...

Juan Carlos Munoz / Cut European ash (Fraxinus excelsior) trunk and felled branches on ground, part of pollarding process. Pollarded European ash trees in fog. La Herreria Forest (Forest of the Blacksmith), Natura 2000 s...

Juan Carlos Munoz / Felled European ash (Fraxinus excelsior) branches on ground and cut trunk, part of pollarding process. Pollarded European ash trees in fog. La Herreria Forest (Forest of the Blacksmith), Natura 2000 s...

Juan Carlos Munoz / Panning shot of cut European ash (Fraxinus excelsior) trunk and felled branches, part of pollarding process. pollarded European ash trees in fog, La Herreria Forest (Forest of the Blacksmith), Natura...

Juan Carlos Munoz / Panning shot of pollarded European ash (Fraxinus excelsior) trees in fog, La Herreria Forest (Forest of the Blacksmith), Natura 2000 site, San Lorenzo de El Escorial, near Madrid, Spain. January.

Franco Banfi / Water hyacinth (Eichhornia sp.) in flower underwater, Pantanal, Mato Grosso, Brazil.

Franco Banfi / Giant water lilies (Victoria sp.) in wetland, Serra do Amolar, Pantanal, Mato Grosso, Brazil.

Franco Banfi / Giant water lilies (Victoria sp.) in wetland, Serra do Amolar, Pantanal, Mato Grosso, Brazil.

Franco Banfi / Giant water lily (Victoria sp.) in flower, Serra do Amolar, Pantanal, Mato Grosso, Brazil.

Franco Banfi / RF - Giant water lilies (Victoria sp.) in wetland, Serra do Amolar, Pantanal, Mato Grosso, Brazil. (This image may be licensed either as rights managed or royalty free.)

Andy Sands / Horned tree hopper (Centrotus cornutus) resting on Dog Rose (Rosa canina) stem, Oxfordshire, England, UK. June. Focus stacked.

Andy Sands / Horned treehopper (Centrotus cornutus) resting on Dog rose (Rosa canina) among thorns, Oxfordshire, England, UK. June. Focus stacked.

Andy Sands / Mountain everlasting (Antennaria dioica) close up of female flowers, Upper Teesdale, County Durham, England, UK. June. Focus stacked.

Andy Sands / Moonwort (Botrychium lunaria) in flower, Upper Teesdale, County Durham, England, UK. June. Focus stacked.

Andy Sands / Marsh fritillary butterflies (Euphydryas aurinia) pair mating on leaf of Devil-bit scabious (Succisa pratensis), Cornwall, England, UK. May. Focus stacked.

Andy Sands / Holly parachute fungi (Marasmius hudsonii) young fruiting bodies on rotting Holly (Ilex aquifolium) leaf, Buckinghamshire, England, UK. January. Focus stacked image.

Andy Sands / Hazel (Corylus avellana) close up of female flower with pollen grains, Hertfordshire, England, UK. February. Focus stacked.

Andy Sands / Common snipe (Gallinago gallinago) standing among Sedges, Upper Teesdale, County Durham, England, UK. June.

Andy Sands / Common snipe (Gallinago gallinago) feeding in frost-covered Watercress (Nasturtium officinale) bed in winter, Hertfordshire, England, UK. December

Andy Sands / Northern bedstraw (Galium boreale) in flower, Upper Teesdale, County Durham, England, UK. June.

Robin Chittenden / Common hop plant (Humulus lupulus) in flower, Norfolk, England, UK. August.

Robin Chittenden / Common hop plant (Humulus lupulus) in flower, Norfolk, England, UK. August.

Robin Chittenden / Stemless carline thistle (Carlina acaulis) in flower, Pyrenees, Spain. August.

Robin Chittenden / Sea kale (Crambe maritima) in flower along shingle beach, Suffolk, England, UK. June.

Robin Chittenden / Germander speedwell (Veronica chamaedrys) in flower, Norfolk, England, UK. May.

Robin Chittenden / Hummingbird hawkmoth (Macroglossum stellatarum) nectaring on Thistle (Cirsium sp.) flower, Pyrenees, Spain. August.

Robin Chittenden / Rock samphire (Crithmum maritimum) in flower, Cornwall, England, UK. August.