The Physiomedical Dispensatory by William Cook, M.D., 1869
LAUREL, SHEEP OR MOUNTAIN LAUREL, CALICO BUSH, SPOONWOOD
Description: Natural Order, Ericaceae. This is a beautiful evergreen shrub, usually from four to eight feet high, (sometimes twenty feet,) growing abundantly in dense thickets on the hills of Virginia and Pennsylvania, and frequently met on high grounds in other States, especially where the soil is springy. Leaves irregularly alternate, ovate-lanceolate, tapering at both ends, two to three inches long, petioled, leathery, very smooth, deep green above and paler beneath, entire. Flowers numerous, light rose-color, pubescent, somewhat clammy, in terminal corymbs; calyx five-parted, small, persistent; corolla tubular bell-shaped, with the margin spreading and five-lobed, large and showy. Stamens ten, hypogynous, turning outwardly and pressing the anthers into corresponding depressions on the corolla till the time for shedding the pollen, when they spring inwardly to the stigmas. Fruit a globose and five-celled pod, with many minute seeds. May and June.
This and other species of the kalmia are much cultivated for their large evergreen leaves, and the beautiful flowers that so richly contrast with the leaves in early summer. The leaves are reputed narcotic, and prussic acid is said to be obtained from them. There is abundant evidence that this acid has no existence whatever in the green leaves, but is developed only after the leaves have undergone partial fermentation. (§32.) In this respect they resemble the leaves of the peach-tree, (see Amygdalus Persica;) and it is an error to judge the leaves by any effects they may produce after having passed through the changes of fermentation. The presence of heat and moisture will determine these changes in a few hours; hence the article should always be used in such form as to prevent all fermentation, as upon liquor. The leaves of kalmia angustifolia, when eaten directly from the shrub, will sometimes kill sheep and horses, yet are eaten by deer, goats, partridges, and other animals, with impunitya fact which of itself proves that its destructiveness is not due to prussic acid in the growing plant; for that poison (in very minute quantities) will kill all animals alike.
Properties and Uses: The leaves are relaxant and moderately stimulant, acting slowly and somewhat persistently upon the glandular system. For this influence, it is particularly valued in secondary syphilis; and is good in combination with such stimulating agents as stillingia, dicentra, menispermum, etc. It acts quite decidedly as a relaxant to serous membranes; and hence may be used in rheumatism, syphilitic pains, the peculiar arterial excitement incident to inflammation of serous membranes, etc. The remedy has been over-praised, yet is of value in the cases named. As stated above, it is not of itself a poison; but any infusion, sirup, or other preparation on water, will pass into the first stage of fermentation in from six to eight hours, and then the article would be a dangerous one to use. On this account, the best standard preparation is that of fluid extract, made after the manner of fluid extract of bonesetonly using sixty percent alcohol. The dose of this ranges from five to ten drops, four times a day. It is usually added to sirups of more stimulating alterants; or the saturated tincture may be added to such sirups. The strength of four ounces of kalmia is sufficient for a gallon of sirup.
Medical Herbalism journal and medherb.com