Jeff Rotman / Man and woman with Cannabis plant in organic Marijuana farm, Pueblo, Colorado, USA, June 2015. . Marijuana has legalized in the state of Colorado, and this farm produces Marijuana for medical and reta...

Jeff Rotman / Person holding large Cannabis bud, in organic Marijuana farm, Pueblo, Colorado, USA, June 2015. . Marijuana has legalized in the state of Colorado, and this farm produces Marijuana for medical and ret...

Konrad Wothe / Ginkgo (Ginkgo biloba) close up of leaves, medicinal plant, Germany

Konrad Wothe / Purple Coneflower (Echinacea purpurea)

Jim Brandenburg / Coneflower (Echinacea sp) field, Wisconsin

Jim Brandenburg / Paper Birch (Betula papyrifera) bark peeling, Minnesota

Konrad Wothe / Chamomile (Anthemis arvensis) and Corn Poppy in flowering meadow, Italy

Heather Angel / Red poppywort (Meconopsis punicea), raindrops on flower and stem. Medicinal plant in Tibet. Balang Shan, Sichuan Province, China. June.

Nick Upton / Aloe vera, an Arabian plant cultivated for medicinal uses, flowering wild on steppe scrubland on Teguise Plain, Lanzarote, Canary Islands, February.

Nick Upton / Aloe vera, an Arabian plant cultivated for medicinal uses, flowering wild on steppe scrubland on Teguise Plain, Lanzarote, Canary Islands, February.

Chris Mattison / Long-tailed wild ginger (Asarum caudatum) flower, Oregon, USA

Paul D Stewart / Historical illustration of Mandrake (Mandragora officinarum) flowers and fruits from the Paris Royal Botanic Garden. Engraving by Stumpf, in 'Dictionarium, Historicum, Criticum, Chronologicum, Geograp...

Jeff Foott / Purple Foxglove (Digitalis purpurea) flowering, Redwood National Park, California

Jeff Foott / Purple Foxglove (Digitalis purpurea) flowering, Redwood National Park, California

Jeff Rotman / Rolled marijuana / cannabis joints, in cannabis dispensary, Denver, Colorado, USA, June 2015. Marijuana has legalized in the state of Colorado, and this farm produces Marijuana for medical and retail...

Jeff Rotman / Rolled marijuana / cannabis joints, in cannabis dispensary, Denver, Colorado, USA, June 2015. Marijuana has legalized in the state of Colorado, and this farm produces Marijuana for medical and retail...

Jeff Rotman / Man and woman with Cannabis plant in organic Marijuana farm, Pueblo, Colorado, USA, June 2015. . Marijuana has legalized in the state of Colorado, and this farm produces Marijuana for medical and reta...

Jeff Rotman / Man tending Cannabis plants in organic Marijuana farm, Pueblo, Colorado, USA, June 2015. Marijuana has legalized in the state of Colorado, and this farm produces Marijuana for medical and retail purpo...

Jeff Rotman / Cannabis / Marijuana buds drying at a commercial in organic Marijuana farm, Pueblo, Colorado, USA, June 2015. Marijuana has legalized in the state of Colorado, and this farm produces Marijuana for med...

Jeff Rotman / Cannabis plants growing under artificial light, in organic Marijuana farm, Pueblo, Colorado, USA, June 2015. . Marijuana has been legalized in the state of Colorado, and this farm produces Marijuana...

Jeff Rotman / Man and woman with Cannabis plant in organic Marijuana farm, Pueblo, Colorado, USA, June 2015. . Marijuana has legalized in the state of Colorado, and this farm produces Marijuana for medical and reta...

Jan Vermeer / Lavender (Lavandula sp) plants drying

Pascal Tordeux / Male fern (Dryopteris filix-mas) medicinal plant against white background.

Pascal Tordeux / Marsh marigold (Caltha palustris) in flower, medicinal plant, Queyras, France, June.

Pascal Tordeux / Yellow flag iris (Iris pseudacorus) in pond with reflections of clouds, medicinal plant. France, May.

Pascal Tordeux / Close up of Tree mallow (Lavatera arborea) flowers, medicinal plant. France.

Pascal Tordeux / Wood anemone (Anemone nemorosa) in flower, medicinal plant. France, April.

Pascal Tordeux / Yellow flag iris (Iris pseudacorus) not yet in flower, at pond edge, medicinal plant. France, April.

Nick Upton / Common comfrey (Symphytum officinale) flowering on the banks of the River Avon, Lacock, Wiltshire, UK, May.

Nick Upton / Common comfrey (Symphytum officinale) flowering on the banks of the River Avon, Lacock, Wiltshire, UK, May.

Eric Baccega / Medicinal plant of the Kalahari desert, known as 'liver plant' to the Naro San Bushmen. Kalahari, Ghanzi region, Botswana, Africa. Dry season, October 2014.

Eric Baccega / Naro San woman digging out the root of a medicinal 'liver plant', Kalahari, Ghanzi region, Botswana, Africa. Dry season, October 2014.

Eric Baccega / Naro San woman digging out the root of a medicinal 'liver plant', Kalahari, Ghanzi region, Botswana, Africa. Dry season, October 2014.

Eric Baccega / Naro San woman eating the root of a medicinal 'liver plant', Kalahari, Ghanzi region, Botswana, Africa. Dry season, October 2014.

Eric Baccega / Naro San woman eating the root of a medicinal 'liver plant', Kalahari, Ghanzi region, Botswana, Africa. Dry season, October 2014.

Simon Colmer / Dutchman's pipe (Aristolochia elegans), Budongo Forest Reserve, Uganda. A medicinal plant used traditionally to treat malaria and snake bite.

Simon Colmer / Silkrubber tree (Funtumia elastica) bark, Budongo Forest Reserve, Uganda. Bark has medicinal properties used to treat asthma, allergies and malaria.

Mark Moffett / Aloe (Aloe sp) latex collected in goat skin by Danho village elder, Sad Dahagan, for stomach and skin cures, Drechba Plateau, Socotra, Yemen

Hiroya Minakuchi / Lavender (Lavandula sp) herb crop in flower, Japan

Hiroya Minakuchi / Lavender (Lavandula sp) field in flower, Japan

Cyril Ruoso / Rosy Periwinkle (Catharanthus roseus) leaves and flowers used for anti-cancer medicine, Berenty Private Reserve, Madagascar

Cyril Ruoso / Rosy Periwinkle (Catharanthus roseus) leaves and flowers used for anti-cancer medicine, Berenty Private Reserve, Madagascar

Cyril Ruoso / Rosy Periwinkle (Catharanthus roseus) harvested by Malagasy woman, leaves and flowers used for anti-cancer medicine, Berenty Private Reserve, Madagascar

Cyril Ruoso / Rosy Periwinkle (Catharanthus roseus) leaves and flowers used for anti-cancer medicine, Berenty Private Reserve, Madagascar

Cyril Ruoso / Rosy Periwinkle (Catharanthus roseus) being harvested by Malagasy woman, leaves and flowers used for anti-cancer medicine, Berenty Private Reserve, Madagascar

Cyril Ruoso / Rosy Periwinkle (Catharanthus roseus) leaves and flowers used for anti-cancer medicine, Berenty Private Reserve, Madagascar

Cyril Ruoso / Rosy Periwinkle (Catharanthus roseus) leaves and flowers used for anti-cancer medicine, Berenty Private Reserve, Madagascar

Cyril Ruoso / Ginseng (Panax sp) root, China

D. Parer & E. Parer-Cook / Lavender being cut, northeastern Tasmania, Australia

Konrad Wothe / Rosy Periwinkle (Catharanthus roseus) flowers, Madagascar

Jabruson / Landa / Ndembo / Silkrubber tree (Funtumia elastica) bark with 30 year-old tapping score marks. Bai Hokou, Dzanga-Ndoki National Park, Central African Republic.

Jabruson / Silkrubber / Landa / Ndembo (Funtumia elastica)seed feathery aerodynamic seed delivery system caught on a tree trunk in moss next to a termite tunnel. Bai Hokou, Dzanga-Ndoki National Park, Central Af...

Jabruson / Silkrubber / Landa / Ndembo (Funtumia elastica)seed feathery aerodynamic seed delivery system caught on a tree trunk in moss next to a termite tunnel. Bai Hokou, Dzanga-Ndoki National Park, Central Af...

Simon Colmer / (Vernonia amygdalina) commonly called bitter leaf because of its bitter taste. In the wild, chimpanzees have been observed ingesting leaves to counter parasitic infections. Medicinal plant: used for w...

Simon Colmer / Leaves and flowers of (Brillantaisia kirungae) a medicinal plant used in Uganda to cure urethritis

Simon Colmer / (Cyphostemma nieriense) Medicinal plant: used in Uganda to cure elephantiasis

Simon Colmer / Wild finger millet (Eleusine indica) also known as Indian goosegrass, Wiregrass, Crowfootgrass, A Medicinal plant used in Uganda to cure stomach ache and chicken pox

Simon Colmer / Leaves of (Tetradenia riparia) a medicinal plant popular in East Africa. said to cure stomach ache, skin diseases and malaria. Anti-bacterial and anti-fungal.

Simon Colmer / Tree marigold (Tithonia rotundifolia) also known as Mexican tournesol, Mexican sunflower or Nitobe chrysanthemum. Medicinal plant: used to improve liver function, and said to cure malaria

Simon Colmer / Indigo (Indigofera ambelacensis) Medicinal plant: used in Uganda to cure worms

Simon Colmer / Flowers and leaves of (Spilanthes mauritiana) a medicinal plant with a high anti-fungal potency

Simon Colmer / Common St. Pauls wort (Sigesbeckia orientalis) Medicinal plant: used in Uganda to cure skin and fungal infections and syphilis

Simon Colmer / Madagascar periwinkle (Catharanthus or Vinca roseus) Medicinal plant: used to cure hypertension, kidney failure, malaria and diabetes. Used in the treatment of leukemia.

Simon Colmer / African Rosemallow also known as Maple Sugar, Red Hibiscus, Cranberry Shield (Hibiscus acetosella) Medicinal plant: used in Uganda as a blood tonic, leaves are edible and good source of vitamin C.

Simon Colmer / Creeping woodsorrel (Oxalis corniculata) Medicinal plant: used in Uganda to cure toothache, eliminate scars and as a diuretic. Entire plant is rich in vitamin C

Simon Colmer / Flowers and leaves of (Bothriocline tomentosa) medicinal plant used to cure diarrhoea and stop vomiting

Simon Colmer / Flower and leaves of (Bothriocline tomentosa) medicinal plant used to cure diarrhoea and stop vomiting

Simon Colmer / Candle Bush seed pods (Senna alata) also known as a Candelabra Bush, Empress Candle Plant, Ringworm Tree. Medicinal plant: effective fungicidal against ringworm and other fungal infections of the ski...

Simon Colmer / Vangueria leaves (Vangueria apiculata) a medicinal plant used to cure intestinal worms and stomach ache

Simon Colmer / Steudner's Dragon tree (Dracaena steudneri) Medicinal plant used as an anti-bacterial, anti-viral and combats high blood pressure

Michael & Patricia Fogden / St. John's-wort (Clusiaceae) fruit, one of them open exposing seeds covered by arils, Monteverde Cloud Forest Reserve, Costa Rica

Christian Ziegler / Embara Indian man with collected plants used for medical purposes, Chagres River, Barro Colorado Island, Panama

Simon Colmer / Calabash / Kamandal fruit (Crescentia cujete) Fruit crop grown for use as a container - used to carry water and other liquids. Also medicinal plant naturalised in India, New Delhi, India, November

Daniel Heuclin / Madagascar Periwinkle / Cacapoule (Catharanthus roseus) growing in an Amerindian village. Introduced to French Guiana as a medicinal plant for treatment of leukemia, lymphoma, and diabetes. August 200...

Daniel Heuclin / Coca leaves (Erythroxylum coca var. coca) held in the hand, main commercial source of cocaine, South America

Pete Oxford / Produce market where most goods are brought in by ship from the mainland, Puerto Ayora, Santa Cruz Island, Galapagos Islands, Ecuador

Miles Barton / Desert hyacinth (Cistanche tubulosa) parasitic plant with underground tuber, flowering in desert, Dubai, United Arab Emirates. Boiled stem traditionally used to cure diarrhoea. Believed to be aphrodis...

Miles Barton / Desert hyacinth (Cistanche tubulosa) parasitic plant with underground tuber, flowering in desert, Dubai, United Arab Emirates. Boiled stem traditionally used to cure diarrhoea. Believed to be aphrodis...

Miles Barton / Desert hyacinth (Cistanche tubulosa) parasitic plant with underground tuber, flowering in desert, Dubai, United Arab Emirates. Boiled stem traditionally used to cure diarrhoea. Believed to be aphrodis...

Konrad Wothe / Mudar (Calotropis procera) flowering, Libya

Albert Lleal / Opium Poppy (Papaver somniferum) dry seed pods, Spain

Suzi Eszterhas / Chimpanzee (Pan troglodytes) mother with three month old infant swallowing Rubia cordifolia for medicinal purposes, western Uganda

Kevin Schafer / Rosy Periwinkle (Catharanthus roseus) leaves and flowers used for anti-cancer medicine, Madagascar

Ingo Arndt / Purple Foxglove (Digitalis purpurea) field, Europe

Ingo Arndt / Purple Foxglove (Digitalis purpurea) flowers, Europe

Ingo Arndt / Purple Foxglove (Digitalis purpurea) flowers, Europe

Ingo Arndt / Red Poppy (Papaver rhoeas) field, Europe

Ingo Arndt / Red Poppy (Papaver rhoeas) flowers, Europe

Jose B. Ruiz / Chilli pepper plants {Capsicum annum acuminatum} medicinal cultivation. Alicante, Spain

Jose B. Ruiz / Chilli pepper plants {Capsicum annum acuminatum} medicinal cultivation. Alicante, Spain

Patricio Robles Gil / Coastal Agave (Agave shawii) blooming, Cedros Island, Pacific coast, Baja California, Mexico

Michael & Patricia Fogden / Herb layer showing diversity of leaf shapes, mid-elevation, seedling of (Heliconia reticulata), Costa Rica

Pete Oxford / Rosy Periwinkle (Catharanthus roseus) a medicinal plant in bloom, Isalo Massif, Isalo National Park, Madagascar

Tim Fitzharris / American Painted Lady (Cynthia virginiensis) butterfly on Coneflower (Echinacea sp), New Mexico

Phil Chapman / Traditional Huli land owner in medicinal plant garden, Tani valley, Papua New Guinea

Jean E. Roche / Fenugreek {Trigonella fenu-graecum} seeds, one of the most ancient medicinal plant known, France