Synonyms: Lactuca scariola Other names: wild lettuce Nomenclature: serriola = with small teeth (leaves) Nativity / Invasiveness: introduced plant, weed
General: plant with milky sap, 30-150 cm tall. Growth habit: biennial or winter annual. Stems: erect, stout, sometimes stiff-hairy below.
Leaves: alternate, mostly 5-30 cm long and 1-10 cm wide, prickly on the midrib beneath, more finely so on the margins, pinnately lobed or (in var. integrata) lobeless, commonly twisted at the base to lie in a vertical plane, clasping stem with small, arrow-shaped lobes.
Flowerheads: yellow, 10-15 mm wide, with 13 to 27 ray florets only, numerous in open clusters. Involucre 10-15 mm high in fruit, with overlapping bracts in 3 rows.
Fruits: achenes, gray or yellowish, the body 3-4 mm long and a third as wide, compressed, prominently several-nerved on each face, with small spines above, at least marginally, the slender beak equaling to twice as long as the body. Pappus of white, hair-like bristles.
A weed of fields and disturbed areas in all parts of MT. Native of Europe, now naturalized in most of the U.S.
Young, tender leaves of prickly lettuce have been eaten - raw or cooked. They are said to taste mild and make an excellent salad, but the whole plant becomes bitter as it gets older, especially when coming into flower. As a potherb it needs very little cooking. Caution should be used, however, since large quantities can cause digestive upsets. Young shoots can be cooked and used as an asparagus substitute.
The whole plant is rich in a milky sap that flows freely from any wounds. This hardens and dries when in contact with the air. The sap contains 'lactucarium', which is used in medicine for its mildly pain-relieving, antispasmodic, digestive, urination-inducing, hypnotic, narcotic and sedative properties. Lactucarium has the effects of a feeble opium, but without its tendency to cause digestive upsets, nor is it addictive. It has been taken internally in the treatment of insomnia, anxiety, neuroses, hyperactivity in children, dry coughs, whooping cough, rheumatic pain etc. The sap has also been applied externally in the treatment of warts. Concentrations of lactucarium are low in young plants and most concentrated when the plant comes into flower. The plant should be used with caution, and never without the supervision of a skilled practitioner. Even normal doses can cause drowsiness, excess causes restlessness and overdoses can cause death through cardiac paralysis.
var. integrata or f. integrifolia: Leaves mostly without lobes. It may represent merely an infusion of genes from the cultivated lettuce, L. sativa.