The plant and especially the leaves and tops of Comptonia asplenifolia, Aiton (Myrica asplenifolia, Linné; Myrica Comptonia, De Candolle).
COMMON NAMES: Sweet fern, Meadow fern, Ferngale.
Botanical Source.—Sweet fern is a low, indigenous shrub, with a long, horizontal root, and growing from 2 to 4 feet high, the main stem being covered with a rusty, brown bark, which becomes reddish in the branches, and white-downy in the young shoots. The leaves are numerous, on short peduncles, from 3 to 4 inches in length, 1/2 inch broad, alternate, linear-lanceolate, sinuate-pinnatifid, resembling the leaves of the spleenwort fern, brown, rather downy on the under side, shining on the upper. The stipules in pairs and acuminate. The flowers are green, monoecious, amentaceous, appearing before the leaves; barren ones in long, erect, cylindrical, loosely imbricated catkins, terminal and lateral, with deciduous, 1-flowered bracts; the fertile ones in ovate, densely imbricated catkins, situated below the barren ones, with 1-flowered bracts. Stamens 6, adhering in pairs. Sepals 6, larger than the bracts; styles 2, capillary. The fruit is a small, ovate, brown, 1-celled nut (L-W.).
History.—This plant is found growing in thin, sandy soils, or dry, rocky woods, from Maine to Kentucky, flowering in May. The whole plant possesses a spicy, aromatic odor, especially when bruised, and an aromatic, astringent, faintly bitterish taste. The whole herb is used, and imparts its virtues to water or alcohol. The leaves have been used in the rural districts of New York state as a substitute for tea.
Chemical Composition.—H. K. Bowman (Amer. Jour. Pharm., 1869, p. 194), found the leaves to contain 8.2 per cent of tannin, corroborated by Charles G. Manger, who, in 1894, made a complete analysis of both the rhizome and the leaves of Myrica asplenifolia. He found the amount of tannin to vary with the season; dried January leaves containing 7.06 per cent, July leaves 10.28 per cent. Tannin in the dried rhizome reached a maximum of 6 per cent in a sample collected in August. Starch was not found in the leaves, but the rhizome contained 8.24 per cent. By distilling the leaves with water, Mr. Manger isolated a small amount of an aromatic volatile oil, which was liable to resinify upon exposure to the air. R. T. Chiles, in 1873, found gallic acid in the leaves, the usual plant constituents, and a body resembling saponin. Peacock subsequently could detect traces only of gallic acid in a January specimen of the rhizome, and none at all in a specimen collected in June (Amer. Jour. Pharm., 1892).
Action, Medical Uses, and Dosage.—Tonic, astringent, and alterative. Used in diarrhoea, dysentery, hemoptysis, leucorrhoea, rheumatism, debility succeeding fevers, and in rachitis. A decoction of it is very useful in the summer complaints of children, when given as an auxiliary. A pillow of the leaves is beneficial to rachitic children, and they may be used as a fomentation in contusions and rheumatism. Dose of the decoction, from 1 to 4 fluid ounces, 3 or 4 times a day.