_Pennyroyal_[1779]; F. _Menthe pouliot_, _Pouliot vulgaire_; G. _Polei_.
=Botanical Origin=—_Mentha Pulegium_ L., a small perennial aromatic
plant, common throughout the south of Europe and extending northward
to Sweden, Denmark, England and Ireland, eastward to Asia Minor and
Persia, and southward to Abyssinia, Algeria, Madeira and Teneriffe. It
has been introduced into North[1780] and South America. For medicinal
use it is cultivated on a small scale.
=History=—Pennyroyal was in high repute among the ancients. Both
Dioscorides and Pliny describe its numerous virtues. In Northern
Europe it was also much esteemed, as may be inferred from the frequent
reference to it in the Anglo-Saxon and Welsh works on medicine.
Gerarde considered the plant to be “so exceedingly well known to all
our English nation” that it needed no description. In his time (_circa_
1590), it used to be collected on the commons round London, whence
it was brought in plenty to the London markets. At the present day
pennyroyal has fallen into neglect, and is not named in the British
Pharmacopœia of 1867.
=Description=—The plant has a low, decumbent, branching stem, which in
flowering rises to a height of about 6 inches. Its leaves, scarcely
an inch in length and often much less, are petiolate, ovate, blunt,
crenate at the margin, dotted with oil-glands above and below. The
flowers are arranged in a series of dense, globose whorls, extending
for a considerable distance up the stem. The whole plant is more or
less hairy. It has a strong fragrant odour, less agreeable to most
persons than that of peppermint or spearmint. Its taste, well perceived
in the distilled water, is highly aromatic.
=Chemical Composition=—The most important constituent of pennyroyal
is the essential oil, known in pharmacy as _Oleum Pulegii_, to which
is due the odour of the plant. It has been examined by Kane,[1781]
according to whom it has a sp. gr. of 0·927. Its boiling was found to
fluctuate between 183° and 188° C. The formula assigned to it by this
chemist is C₁₀H₁₆O. We ascertained that it contains no carvol (see page
481.)
=Production=—Pennyroyal is cultivated at Mitcham and is mostly sold
dried; occasionally the herb is distilled for essential oil. The oil
found in commerce is however chiefly French or German, and far less
costly than that produced in England.
=Uses=—The distilled water of pennyroyal is carminative and
antispasmodic, and is used in the same manner as peppermint water.
[1779] _Pennyroyal_, in old herbals _Puloil royal_ is derived from
_Puleium regium_, an old Latin name given from the supposed efficacy of
the plant in destroying fleas (Prior).
[1780] The native Pennyroyal is however a different plant, namely
_Hedeoma pulegioides_ Pers., figured in part 21 (1877) of Bentley and
Trimen’s _Med. Plants_.
[1781] _Phil. Mag._ xiii. (1838) 442.