_Prickly Lettuce_; F. _Laitue vireuse_; G. _Giftlattich_.
=Botanical Origin=—_Lactuca virosa_ L.,[1452] a tall herb occurring
on stony ground, banks and roadsides, throughout Western, Central and
Southern Europe. It is abundant in the Spanish Peninsula and in France,
but in Britain is only thinly scattered, reaching its northern limit in
the south-eastern Highlands of Scotland.
=History=—The introduction of this lettuce into modern medicine is due
to Collin (the celebrated physician of Vienna, mentioned in our article
on Rad. Arnicæ, p. 390), who about the year 1771 recommended the
inspissated juice in the treatment of dropsy. In long standing cases,
this extract was given to the extent of half an ounce a day.
The College of Physicians of Edinburgh inserted _Lactuca virosa_ L.
in their pharmacopœia of 1792, while in England its place was taken
by the Garden Lettuce, _L. sativa_ L. The Authors of the _British
Pharmacopœia_ of 1867 have discarded the latter, and directed that
_Extractum Lactucæ_ shall be prepared by inspissating the juice of _L.
virosa_.
=Description=—The plant is biennial, producing in its first year
depressed obovate undivided leaves, and in its second a solitary
upright stem, 3 to 5 feet high, bearing a pinacle of small, pale yellow
flowers, resembling those of the Garden Lettuce. The stem, which is
cylindrical and a little prickly below, has scattered leaves growing
horizontally; they are of a glaucous green, ovate-oblong, often
somewhat lobed, auricled, clasping, with the margin provided with
irregular spinescent teeth, and midrib white and prickly. The whole
plant abounds in a bitter, milky juice of strong, unpleasant, opiate
smell.
=Chemical Composition=—We are not aware of any modern chemical
examination having been made of _Lactuca virosa_. The more important
constituents of the plant are those found in _Lactucarium_, to the
article on which the reader is referred.
=Uses=—The inspissated expressed juice of the fresh plant is reputed
narcotic and diuretic, but is probably nearly inert.
[1451] Giles, _Pharm. Journ._ xi. (1851) 107.
[1452] Bentham unites this plant with _L. Scariola_ L., but in most
works on botany they are maintained as distinct species.