In North America, it has been documented as introduced in California, Alabama, Iowa, and Washington, DC, and grows wild in other parts of the continent.Lactuca virosa is widespread across much of central and southern Europe. It can be found locally in the south east and east of England. In the rest of Great Britain it is very rare, and in Ireland it is absent. It is also found in the Punjab Region of Pakistan India and Australia where it grows in the wild.Lactuca virosa is a plant in the Lactuca (lettuce) genus, ingested often for its mild psychotropic (specifically hypnotic or sedative) effects which are often described as being similar to those of opium. It is related to common lettuce (L. sativa), and is often called wild lettuce, bitter lettuce, laitue vireuse, opium lettuce, poisonous lettuce, tall lettuce, great lettuce or rakutu-karyumu-so.
Lactuca virosa is biennial, similar to prickly lettuce Lactuca serriola but taller - it can grow to 200cm (80 inches or almost 7 feet). It is also stouter, the stem and leaves are more purple flushed,[disputed - discuss] the leaves are less divided, but more spreading.
The achene is purple black, without bristles at the tip. The pappus is the same as Lactuca serriola.
In the northern hemisphere, it flowers from July until September.
Lactuca virosa was used in the 19th century by physicians when opium could not be obtained. It was studied extensively by the Council of the Pharmaceutical Society of Great Britain in 1911. They discovered two chemicals responsible for the properties of L. virosa; lactucopicrin and lactucin. In the United States, the plant experienced a resurgence in popularity in the 1970s. Today the plant is un-scheduled by the Food and Drug Administration (FDA), meaning it is legal to grow, purchase and own without prescription or license.
A latex which is called lactucarium can be derived from the extract of the stem secretions of Lactuca virosa. Oils and extracts can also be produced from L. virosa. These oils and extracts have sedative properties in rodents. They may be added to tea to help induce sleep. While its use as a galactagogue (a substance that increases breast milk) has been reported, the sedative effects on the baby would strongly argue against its use for this purpose. Many add the greens to salads, though the leaves of L. virosa are more bitter than other salad greens. Smoking involves either dried leaves or a sticky precipitate extracted from the leaves. Beverages can be prepared by soaking the leaves in alcohol.
Lactuca virosa contains flavonoids, coumarins, and N-methyl--phenethylamine.[unreliable sourc] A variety of other chemical compounds have been isolated from L. virosa. One of the compounds, lactucin, is an adenosine receptor agonist in vitro, while another, lactucopicrin, has been shown to act as an acetylcholinesterase inhibitor in vitro.
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