Plant of the week – July 20 – Opium Poppy Papaver somniferum

by John Grace, the University of Edinburgh

Papaver somniferum growing semi-wild in garden conditions (Photo: Julia Wilson).

The Opium Poppy was cultivated from Neolithic times by farmers of the Eastern Mediterranean, being much valued for the psychoactive latex harvested from its unripe seed capsule. This substance was found to relieve pain, dull the senses, produce euphoria and induce sleep. The main psychoactive chemicals in opium are morphine, codeine and thebaine.

Pollination is by large flying insects. Here, a hoverfly (Photo: Julia Wilson).

Opium poppy was named Papaver somniferum by Swedish botanist Carl Linnaeus in 1753. The plant is an annual, colonising waste ground and appearing as a common weed in gardens and arable fields. It is quite distinct from most other poppies, its leaves having a grey-blue (glaucous) appearance, with coarsely-toothed or lobed leaves that clasp the stem. In favourable conditions the plant produces several stems and grows to one metre tall. Flowering stems emerge from leaf axils, each with one flower-bud borne on an often-drooping pedicel. In poor soils or cracks on pavements it may appear as a solitary unbranched stem and a single terminal flower. The flowers are large (25-50 mm) and short-lived (a few days), with four colourful petals. Two large sepals protect the buds and are shed as the flower opens. Pollination is by flying insects, particularly bees and flies, but self-pollination also occurs. The resulting seed capsule works like a pepper-pot, producing up to 5,000 tiny seeds which are released when the structure is shaken by the wind. Seeds require exposure to low temperatures (2-3 oC) for 30-35 days before they will germinate. Germination and seedling establishment may occur at 4 oC.  Opium Poppy is a long-day plant, requiring a photoperiod exceeding 14 hours to trigger flowering. It grows best in fertile moist soils, of pH 6-7. In the UK it is a common wild plant, recorded in 1,527 hectads (out of a possible 2,876), being more common in the east than the west and absent from upland regions. It may have been slow to reach Scotland. The earliest record I found was in Hayward’s The Adventive Flora of Tweedside. She reports an 1872 record ‘by the Tweed’ (this was the bristly subspecies setigerum). More recently, both Dickson et al. (2000) and Smith et al. (2002) record its presence: Dickson finds 27 tetrads for Glasgow. In their 2006 book Change in the British Flora 1987-2004 Braithwaite et al found the species to have increased considerably in recent years.

Most books recognise two subspecies, P. somniferum Ssp. somniferum and the smaller P. somniferum Ssp. setigerum, called Poppy of Troy, which has been suggested as the wild progenitor. However, chromosome counts show the former to be 2n=22 and the latter to be 2n=44, arguing against this simple lineage. Ssp. setigerum, found in a few locations in Southern England, is a bristly species with a narrower capsule; and it produces less morphine – it probably should be considered as a separate species.  

Further general information on P. somniferum can be obtained in Volume 2 of the Springer book on Medical and Aromatic Plants of the World (Baser and Arslan, 2014).

Left: flower-buds emerging in leaf axils; note also the coarsely toothed leaves clasping the stem, right: seed capsules (Photos: John Grace).

There have been centuries of selection and breeding for opium, poppy-seeds, poppy-oil and more recently for flower-gardens. Consequently, the species is variable in form and latex production. Many cultivars are recognised.  Flowers vary in colour: they may be white, red, blue, pink or purple, often in pastel-shades with darker (sometimes black) flecks near the centre of the flower.  Petal colour is  monogenically controlled  with several alleles giving rise to a graded dominance  violet>red>pink>white (Bhandari 1989). Double-flowered varieties are available commercially and may persist as weeds.

Papaver somniferum in several contrasting flower-colours (Photo: Chris Jeffree).

 It is thought that that opium poppy was originally cultivated in the Mediterranean basin from the middle of the sixth millennium BC, where the unknown wild ancestor grew. Aurélie Salavert, at the Muséum National d’Histoire Naturell in Paris, points to the frequent discoveries of Papaver somniferum from Linear Pottery Culture (LPK) sites. LPK is the name given to a major archaeological horizon of the European Neolithic c. 5500–4500 BC, where humans herded livestock, produced ceramic vessels and grew wheat, pea, lentil, hemp and flax over a large area of Europe.  She considers that this crop package originated earlier in the Fertile Crescent and diffused rather rapidly to central Europe – especially to the middle Danube, the upper and middle Elbe, and the Rhine. Opium poppy has also been found at archaeological sites in the Alpine region by the beginning of the fifth millennium BC (Salavert et al. 2018). Thereafter, the poppy was widely cultivated by the Greeks and Romans. Hippocrates (460-357 BC) known as the father of medicine, recommended drinking the juice of the white poppy mixed with the seed of nettle.

Opium producing areas of the world. Papaver somniferum is grown in many other areas for poppy-seed production, and occurs as a weed in most parts of the world except for the humid tropics. Its global distribution may be limited by the flowering response to day-length (it needs long days).

After the Roman Empire fell, various Islamic Empires ruled southern Europe, and many continued to use Dioscorides’ five volume De Materia Medica, translated into Arabic. From this book they learned the medical uses of opium; moreover, Arab traders are believed to have taken opium to China between 400 and 1200 AD and to India by 700 AD. It may have already been in China: the noted Chinese surgeon Hua To of the Three Kingdoms (220-264 AD) used opium preparations and Cannabis indica for his patients to swallow before undergoing major surgery.

The Swiss physician Paracelsus (1493-1541) introduced opium for medical use in Western Europe, and is believed to have invented an opium pill called Laudanum.  However, the English physician Thomas Sydenham (1624-1689) is more generally credited with the first liquid tincture of opium which was also called Laudanum. He mixed opium with wine, saffron, clove and cinnamon and this recipe was used widely in Europe and the Americas until the 20th century. Opium preparations were used in the American Civil War (1861-1865), and many soldiers became addicted to it. Addiction became known as ‘Soldiers Disease’.

Advertising Laudanum for restless and sick babies (USA, circa 1900)

Much information about the preparation of opium in recent times (the 1990s) can be found in an unlikely place: the US Department of Justice, Office of Intelligence (hereafter I’ll call it DoJ 1992). This fully-illustrated 31-page report is focussed on production in China and SE Asia. It describes exactly how the capsules are scored with a sharp blade and allowed to bleed their white latex; it hardens, is scraped off and boiled in water. The resulting solution of opium is reduced to a paste by further boiling. This is the active material, which is smoked in a mixture with tobacco.

The use of opioids as ‘recreational drugs’ was common in literary circles of the Romantic Era (e.g. Samuel Taylor Coleridge, Lord Byron, John Keats and Percy Shelley). Regular users of opioids may suffer from addiction, sometimes with fatal consequences. In 2017 drug addiction from opioids accounted for 47,600 deaths per year  in the USA alone. The legalistic aspects of opium and the morphine-derivative heroin as narcotics are huge subjects, beyond the scope of this short blog. A time-line can be viewed at

Opium poppy is (I think) the only plant species to have caused two wars. The Chinese Jiaqing Emperor made opium illegal in 1729, 1799, 1814, and 1831, but the British East India company continued illegally to trade opium produced in its Bengal plantations.  A blockade of foreign ships bringing opium to China ensued, and the smugglers lost 1,300 tons of opium. In retaliation, Britain sent troops in 1840; the bloody First Opium War was concluded by the Treaty of Nanking (now Nanjing) in 1842. The treaty forced China to cede Hong Kong Island to Britain  ‘in perpetuity’. The second Opium War (1856-58) involved France as well (because a French missionary was murdered). In settlement, China was forced to re-legalize the opium trade. The ripples from these wars are still felt today.

Papaver somniferum is both a friend and foe of humans.


Baser K.H.C., Arslan N. (2014) Opium Poppy (Papaver somniferum). In: Yaniv Z., Dudai N. (eds) Medicinal and Aromatic Plants of the Middle-East. Medicinal and Aromatic Plants of the World, vol 2. Springer, Dordrecht.

Bhandari MM (1989)  Inheritance of petal colour in Papaver somniferum L. Journal of Horticultural Science 64, 339-340.

Braithwaite ME, Ellis RW & Preston CD (2006) Change in the British Flora 1987-2004. BSBI.

Dickson JH et al. (2000) The Changing Flora of Glasgow. Edinburgh University Press.

DoJ (1992) Opium Poppy’ Cultivation and Heroin Processing in Southeast Asia. US Department of Justice, Washington. 141189NCJRS.pdf

Salavert A et al. (2018) The opium poppy in Europe: exploring its origin and dispersal during the Neolithic. Antiquity 2, e1.

Smith PM et al. (2002) Plant Life of Edinburgh and the Lothians. Edinburgh University Press.

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