"The leaves and tops of Hedeoma pulegioides (Linné), Persoon"—(U. S. P.); (Melissa pulegioides, Linné; Cunila pulegioides, Willdenow; Ziziphora pulegioides, Desfontaines).
COMMON NAMES: Pennyroyal, American pennyroyal, Tick-weed, Squawmint.
ILLUSTRATIONS: Bentley and Trimen, Med. Plants, 200; Barton, Med. Bot., 41.
Botanical Source.—This is an indigenous annual plant. It has a fibrous, yellowish root, an erect, branching, pubescent, rather angular stem, from 6 to 12 inches high. The leaves are 1/2 inch or more long, opposite, oblong, have 1 or 2 teeth on each side, are smooth above, rough below, narrowed at the base, and borne on short petioles; the floral leaves are similar. The flowers are quite small, light-blue, in 6-flowered, axillary whorls. Calyx ovoid or tubular; gibbous on the lower side near the base, with 13 striae; upper lip 3-toothed; lower 2-cleft; threat hairy. The corolla tube is as long as the calyx, downy, and 2-lipped; upper lip erect, flat and notched at the apex; the lower spreading and 3-cleft, the lobes being nearly equal. Stamens 2, ascending and filiform; the cells of the anthers diverging. Seeds 4, and oblong (W.—G.—L.).
History, Description, and Chemical Composition.—This herb was placed by Linnaeus in the genus Melissa, and afterward Cunila, from which it was removed by Persoon, and placed in the genus Hedeoma. It must not be confounded with Mentha Pulegium, Linné, or European pennyroyal, which has similar action and uses. It is a well-known plant, growing in barren woods and dry fields, and particularly in limestone countries, flowering from June to September and October, rendering the air fragrant for some distance around it. It is common to nearly all parts of the United States. It has a peculiar, aromatic odor, which, however, is very offensive to some persons, and a hot, pungent, aromatic taste. It imparts its virtues to boiling water by infusion; boiling destroys its activity by evaporating the volatile oil, on which its properties depend. The oil (see Oleum Hedeomae), its chief constituent, may be obtained by distillation with water, and is often employed, or its tincture, instead of the herb itself; it is of a light-yellow color, and specific gravity ranging from 0.930 to 0.940. Hedeoma thymoides, Gray, a Texan plant, has similar properties. The official drug is thus described. "Leaves opposite, short-petioled, about 12 Mm. (1/2 inch) long, oblong-ovate, obscurely serrate, glandular beneath; branches roundish, quadrangular, hairy; flowers in small, axillary cymules, with a tubular-ovoid, bilabiate and five-toothed calyx, and a pale blue, spotted, bilabiate corolla, containing 2 sterile and 2 fertile, exserted stamens; odor strong, mint-like, taste warm and pungent"—(U.S. P.).
Action, Medical Uses, and Dosage.—Pennyroyal is a stimulant, diaphoretic, emmenagogue, and carminative. The warm infusion used freely, will promote perspiration, restore suppressed lochia, and excite the menstrual discharge when recently checked, especially by colds; it is often used by females for this last purpose, a large draught being taken at bedtime, the feet having been previously bathed in warm water. It is an excellent remedy for common colds. A gill of brewer's yeast added to the draught is reputed a safe and certain abortive. The warm infusion may likewise be employed with advantage in the flatulent colic of children. The oil, or its tincture, is also administered as a carminative and antiemetic, and has been of benefit in hysteria, whooping-cough, spasms, etc. Hedeoma is accredited with galactagogue powers, but it acts best probably when diminished lactation is due to acute colds. Dr. M. H. Hennell (Trans. Ohio E. M. Assoc., 1895, p. 81), justly extols the remedy in flatulent colic, not only to serve as an anti-spasmodic, but to act as a calmative of the nervous phenomena. He uses it extensively in threatened convulsions of children, in hysteria from menstrual derangements, in puerperal septicaemia, and to hasten or aid the eruptive process in the exanthemata. Dr. Hennell praises it especially as a remedy for chronic amenorrhoea, and gives the indications below named. It is likewise used as a rubefacient in rheumatism, and united with linseed oil, as an application to burns and scalds. Dose of the oil, from 2 to 10 drops; of a saturated tincture, 1 to 2 fluid drachms. The infusion may be freely administered. Dr. Toothacker (Phila. Jour. of Hom., Vol. II, p. 655) reports a case of poisoning in a woman from one fluid drachm of oil of pennyroyal, The symptoms were: Severe headache, difficult swallowing, intense nausea, with severe retchings without emesis, intolerable bearing down, labor-like pains, abdominal tenderness, constipation, dyspnoea, limbs semiparalytic, and nervous weakness and prostration (Millspaugh's Amer. Med. Plants).
Specific Indications and Uses.—Amenorrhoea of long standing, with pallor and anemia, and dark circles about the eyes. Patient complains of languor and lassitude, takes cold easily, has pain in the back and limbs, and exhibits full, prominent veins (Hennell).
King's American Dispensatory, 1898, was written by Harvey Wickes Felter, M.D., and John Uri Lloyd, Phr. M., Ph. D.