Chris Mattison / Stigma and anthers of Cactus flower (Notocactus crassigibbus). Cultivated plant. Focus-stacked image.

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

Stephen Dalton / Close up of the inside of a foxglove (Digitalis purpurea) showing the pistil and stamen, UK.

Wild Wonders of Europe / Bartocha / Common peony (Paeonia officinalis) close up of stamens and stigma, Monti Sibillini National Park, Italy, May.

Nick Upton / Hoverfly (Myathropa florea), using proboscis to feed on pollen from anthers of Ivy flowers (Hedera helix). Wiltshire garden, UK, September

Albert Lleal / Albany Bottlebrush (Callistemon speciosus) SEM close-up view of the pollen covered anther at 70x magnification

Tim Fitzharris / Blanketflower (Gaillardia sp) close-up showing pollen covered anthers and dense pistils in center, North America

Robert Thompson / Trumpet lily (Lilium 'Yellow Planet') close-up of stamens, County Down, Northern Ireland. August.

Robert Thompson / Yellow loosestrife (Lysimachia punctata) close up of stamens, County Down, Northern Ireland. July.

Robert Thompson / Passion flower (Passiflora caerulea) stamen detail, Banbridge, County Down, Northern Ireland. April.

Robert Thompson / Hawthorn (Crataegus laevigata) flowers, Brackagh Moss National Nature Reserve, County Armagh, Northern Ireland. May.

Robert Thompson / Greater stitchwort (Stellaria holostea) stamen detail, Brackagh Moss National Nature Reserve, County Armagh, Northern Ireland. April.

Paul Harcourt Davies / Nettle-leaved bellflower (Campanula trachelium) in flower, Lazio, Italy. July.

Paul Harcourt Davies / Rattlesnake root purple lettuce (Prenanthes purpurea) in flower, Tuscany, Italy. July.

Paul Harcourt Davies / Dog rose (Rosa canina) in flower, Podere Montecucco Garden, Umbria, Italy. June.

Paul Harcourt Davies / Dog rose (Rosa canina) in flower, Podere Montecucco Garden, Umbria, Italy. June.

Paul Harcourt Davies / Blackberry bush (Rubus fruticosus) in flower, Umbria, Italy. June.

Paul Harcourt Davies / Lemon (Citrus limon) flower, Umbria, Italy. June.

Paul Harcourt Davies / St Bruno's lily (Anthericum liliastrum) in flower, Umbria, italy. May.

Paul Harcourt Davies / Tragopogon x mirabilis, a natural hybrid between Goat's beard (Tragopogon pratensis) and Salsify (Tragopogon porrifolius) found in several colour forms, Umbria, Italy. May.

Paul Harcourt Davies / Close up of Goat's beard (Tragopogon pratensis) flower, Umbria, Italy. May.

Paul Harcourt Davies / Common dogwood (Cornus sanguinea) flower head, Umbria, Italy. May.

Paul Harcourt Davies / Mediteranean medlar tree (Crataegus azarolus) flowers, Umbria, Italy. May.

Paul Harcourt Davies / Silvery crocus (Crocus biflorus) in flower growing on path, Tuscany, Italy. January.

Paul Harcourt Davies / Alpine crocus (Colchicum alpinum), an autumn crocus, in flower, Lazio, Italy. August.

Paul Harcourt Davies / Yellow water-lily (Nuphar lutea) in flower, Umbria, Italy. May.

Paul Harcourt Davies / White rockrose (Helianthemum appeninum) in flower, Sibillini, Umbria, Italy. May.

Will Watson / Blackthorn or sloe (Prunus spinosa) blossom in hedgerow, Herefordshire, England, UK.

Bruce Thomson / Mountain devil (Lambertia formosa) flowering in Eucalypt (Myrtaceae) forest understorey, New South Wales, Australia.

Edwin Giesbers / North African knapweed / Lesser star thistle (Centaurea diluta) Tenerife, Canary Islands

Edwin Giesbers / North African knapweed / Lesser star thistle (Centaurea diluta) close up of stamens on central disc, Tenerife, Canary Islands

John Cancalosi / Cactus bee (Diadasia rinconis) collecting nectar and pollen on Prickly pear (Opuntia sp.) blossom, Sonoran Desert, Arizona, UK.

Robert Thompson / Alstroemeria Lily, close up of stamens. Studio image.

Robert Thompson / Tulip (Tuplia species) close up of anthers, Banbridge, County Down, Northern Ireland.

Robert Thompson / Tulip (Tuplia species) close up of stigma and anthers, Banbridge, County Down, Northern Ireland.

Robert Thompson / Herb-robert (Geranium robertianum) close up of anthers and stigma, Clare Glen, Northern Ireland.

Alex Hyde / Small scabious (Scabiosa columbaria) anther detail showing pollen. This flower was discovered very late in the season. Peak District Natioanl Park, Derbyshire, UK. November. Focus stacked image.

Dave Watts / Long purpleflag (Patersonia occidentalis). Tasmania, Australia. December.

Rolf Nussbaumer / Red columbine (Aquilegia canadensis). Hill Country, Texas, USA.

Nick Upton / Wood avens (Geum urbanum). Gloucestershire Wildlife Trust Lower Woods Reserve, England, UK. June.

Nick Upton / Spiked star-of-Bethlehem (Ornithogalum pyrenaicum), close up. A nationally scarce species. Wiltshire, England, UK. June.

Nick Upton / Herb Paris (Paris quadrifolia), close up. Wiltshire, England, UK. May.

Nick Upton / Hoary plantain (Plantago media) on white background. Salisbury Plain SSSI, Wiltshire, England, UK. May.

Nick Upton / Upright brome grass (Bromus erectus) with yellow anthers. Salisbury Plain, Wiltshire, England, UK. May.

Linda Pitkin / Field pepperwort (Lepidium campestre), Surrey, England, UK. June.