An annual or biennial, glabrous or nearly so, tall, erect, very leafy. Stems erect, 2-5ft., branched, usually prickly towards the base. Leaves sessile, 5-7in., pinnatifid, segments toothed, pointing downwards ; lower surfaces usually prickly on the midrib and nerves ; stem-leaves lobed at the base. Heads ½in. long, erect ; flowers yellow. Achenes brown ; beak very slender, about as long as the body (Collett).
" Inflorescence," says J. D. Hooker, "variable, sometimes 12in. diam. ; with incurved, ascending corymbose branches, at others laxly paniculate. Branches and peduncles. White, with many appressed, green, cordate bracts. Involucre-bracts ovate, inner linear ; ligules yellow or dull-reddish outside. Achenes ¼in., including the very slender beak, ribbed, pale ; pappus 1/5in.
Use : — In the wild state the seeds produce to a certain extent narcotic and sedative effects, but these appear to be almost entirely removed by cultivation (Dymock).
From the sap may be prepared a resinous dry juice, known commercially as Lactucarium. The common Lettuce yields only about 18 grains for each plant, but the scented and wild English Lettuce, Lactuca virosa, Linn., yields 56 grains. This juice is prepared just as the plant begins to flower. Dr. Duncan, nearly a century ago, showed that the juice might be used as a substitute for opium, having most of the properties of that drug without its binding effects. Smith, in his Dictionary of Economic Plants, mentions an instance, in July 1879, where a man died from the effects of the narcotic, through eating lettuce. Thus, it would seem that the strength of the narcotic varies considerably, and that the drug is not certain. Its action is not so reliable as opium, but it may be used as a mild hypnotic. Dose 2 to 10 grains of the dry juice. The officinal preparation is the Extract prepared from the fresh plant ; a mild sedative, anodyne, purgative, diuretic, diaphoretic, and antispasmodic, said to be useful in the treatment of the coughs in phhisis, bronchitis, asthma and pertussis. It has also been recommended for rheumatism and insanity with doubtful results. In native medical practice, a decoction of the seeds is used as a demulcent. Dose 3ii to 3ss. (Watt).
