_Radix Serpentariæ Virginianæ_; _Virginian Snake-root_, _Serpentary
Root_; F. _Serpentaire de Virginie_; G. _Schlangenwurzel_.
=Botanical Origin=—_Aristolochia Serpentaria_ L., a perennial herb,
commonly under a foot high, with simple or slightly branched, flexuose
stems, producing small, solitary, dull purple flowers, close to the
ground. It grows in shady woods in the United States, from Missouri and
Indiana to Florida and Virginia,—abundantly in the Alleghanies and in
the Cumberland Mountains, less frequently in New York, Michigan and the
other Northern States. The plant varies exceedingly in the shape of its
leaves.
=History=—The botanists of the 16th century, being fond of
appellations alluding to the animal kingdom, gave the names of
_Serpentaria_ or Colubrina, _i.e._ snake-root, to the rhizome of
_Polygonum Bistorta_ L. In America it was not the appearance, but
the application of the drug under notice to which it owes the name
snake-root.
The earliest account of _Virginian_ snake-root is that of Thomas
Johnson, an apothecary of London who published an edition of Gerarde’s
Herbal in 1636. It is evident however that Johnson confounded a species
of _Aristolochia_ from Crete with what he calls “that snake-weed that
was brought from Virginia and grew with Mr. John Tradescant at South
Lambeth, anno 1632.” It was very briefly noticed by Cornuti in his
_Canadensium Plantarum Historia_ (1635), and in a much more intelligent
manner by Parkinson in 1640. These authors, as well as Dale (1693) and
Geoffroy (1741), extol the virtues of the root as a remedy for the bite
of the rattlesnake, or of a rabid dog. Serpentary was introduced into
the London Pharmacopœia in 1650.
=Description=—The snake-root of commerce includes the rhizome, which
is knotty, contorted, scarcely 1 inch in length by ⅛ of an inch in
thickness, bearing on its upper side the short bases of the stems of
previous years, and throwing off from the under, numerous, slender,
matted, branching roots, 2 to 4 inches long. The rhizome is often still
attached to portions of the weak, herbaceous stem, which sometimes
bears the fruit,—more rarely flowers and leaves. The drug has a dull
brown hue, an aromatic odour resembling valerian but less unpleasant,
and a bitterish aromatic taste, calling to mind camphor, valerian and
turpentine.
=Microscopic Structure=—In the rhizome, the outer layer of the bark
consists of a single row of cuboid cells; the middle cortical portion
(_mesophlœum_) of about six layers of larger cells. In the liber, which
is built up of numerous layers of smaller cells, those belonging to
the medullary rays are nearly cuboid with distinctly porous walls,
those of the liber bundles being smaller and arranged in a somewhat
crescent-shaped manner. Groups of short, reticulated or punctuated
vessels alternate in the woody rays with long, porous, ligneous cells;
those close to the pith having thick walls. The largest cells of all
are those composing the pith; the latter, seen in transverse section,
occupies not the very centre of the rootstock, but is found nearer to
its upper side. The rootlets exhibit a central fibro-vascular bundle,
surrounded by a nucleus-sheath. In the mesophlœum both of the rootstock
and the rootlets, there occur a few cells containing a yellow essential
oil. The other cells are loaded with starch.
=Chemical Composition=—Essential oil exists in the drug to the extent
of about ½ per cent.; and resin in nearly the same proportion. The
outer cortical layer, as well as the zone of the nucleus-sheath,
contains a little tannin, and a watery infusion of the drug is coloured
greenish by perchloride of iron. Neutral acetate of lead precipitates
some mucilage as well as the bitter principle, which latter may also be
obtained by means of tannic acid. It is an amorphous, bitter substance,
which deserves further investigation. By an alkaline solution of
tartrate of copper the presence in serpentary of sugar is made evident.
=Commerce=—Virginian snake-root is imported from New York and Boston,
in bales, casks or bags.
=Uses=—The drug is employed in the form of an infusion or tincture as
a stimulating tonic and diaphoretic; it is more often prescribed in
combination with cinchona bark than by itself. Its ancient reputation
for the cure of snake-bites is now disregarded.
=Adulteration and Substitution=—Virginian snake-root is said to be
sometimes adulterated with the root of _Spigelia marilandica_ L.,
which has neither its smell nor taste (see p. 433); or with that of
_Cypripedium pubescens_ L., which it scarcely at all resembles. It is
not uncommon to find here and there in the serpentary of commerce, a
root of _Panax quinquefolium_ L. accidentally collected, but never
added for the purpose of adulteration.
The root of _Aristolochia reticulata_ Nutt., a plant of Louisiana and
Arkansas, has been brought into commerce in considerable quantity
as _Texan_ or _Red River Snake-root_.[2224] We are indebted for an
authentic specimen from the Cherokee country to Mr. Merrell, a large
dealer in herbs at St. Louis, Missouri, who states that all the
serpentary grown south-west of the Rocky Mountains is the produce of
that species. The late Prof. Parrish of Philadelphia was kind enough
to supply us with specimens of the same drug, as well as with reliable
samples of true _Virginian_ or _Middle States Snake-root_.
The Texan snake-root is somewhat thicker and less matted than that
derived from _A. Serpentaria_, but has the odour and taste of the
latter; some say it is less aromatic. The plant, portions of which
are often present, may be easily distinguished by its leaves being
_coriaceous_, _sessile_ and _strongly reticulated_ on their under
surface.
[2224] Wiegand in _American Journ. of Pharm._ x. (1845) 10; also
_Proceedings of the Am. Pharm. Association_, xxi. (1873) 441.