The leaves of Rhododendron chrysanthum, Linné.
COMMON NAMES: Yellow-flowered rhododendron, Rosebay, Snow rose.
Botanical Source.—This is a small bush, with the stem from 1 to 1 1/2 feet high, spreading, very much branched, often almost hidden among moss, from which the tips only of its shoots are protruded. The leaves are alternate, of the texture of a laurel leaf, ovate, somewhat acute, tapering into the stalk, reticulated and very rough above, and paler and smoother underneath. The flowers are large, showy, nodding, and borne on clustered, terminal, loose peduncles, emerging from among large downy scales. Corolla campanulate, 5-cleft, with rounded segments, of which the three upper are rather the largest, and streaked with livid dots next the tube, the lower unspotted. Stamens 10, unequal, and deflexed; the anthers oblong, incumbent, and without appendages, opening by two terminal pores. Capsule ovate, rather angular, 5-celled, 5-valved, and septicidal; seeds numerous and minute (L.).
History, Description, and Chemical Composition.—Rhododendron is an elegant evergreen shrub, inhabiting the mountains of Siberia, with large, yellow flowers, which appear in June and July. The leaves are the parts used in medicine, and should be gathered as soon as the capsules have ripened. They have a faint odor when recent, which is lost by drying; their taste is somewhat bitter, slightly acrid and astringent. Water or alcohol extracts their properties. Besides tannic acid and the other usual plant constituents, a small amount of essential oil is present, as well as the poisonous andromedotoxin (Plugge and De Zaayer, Amer. Jour. Pharm., 1889, p. 361).
Action, Medical Uses, and Dosage.—Yellow rhododendron contains a stimulant, narcotic principle; for it increases the heat of the body, excites thirst, and produces diaphoresis, or an increased discharge of the other secretions or excretions, and which are generally followed by a decrease of action of the arterial system. With some persons it causes emeto-catharsis, inebriation, and delirium. The Siberians use a decoction of it in chronic rheumatism and gout. They put about 2 drachms of the dried shrub in an earthen pot, with about 10 ounces of boiling water, keeping it near a boiling heat for a night, and this they take in the morning. Beside its other effects, it is said to produce a sensation of prickling or creeping in the painful parts; but in a few hours the pain and disagreeable symptoms are relieved, and 2 or 3 doses generally complete the cure. The use of liquids is not allowed during its operation, as this is apt to induce vomiting (Ed.—Coxe). It is a valuable remedy, used in Russia, Germany, and sometimes in France and England, but scarcely at all in this country. That it possesses a decided control over the circulation, acting like the special sedatives, slowing the quickened pulse by giving increased heart power and removing capillary obstruction, seems well established. Myalgic pains, whether rheumatic or not, but especially of the facial and ocular region, appear to be the special indication for its use. It has been employed in acute testicular, and ovarian affections, as well as in chronic orchitis and hydrocele. The dose should be minute, from a fraction of a drop to a drop of a saturated tincture. Probably our native species would be fully as effective.
Specific Indications and Uses.—Myalgic pain, particularly of the face; "face-ache"; pain in the ocular muscles.
Related Species.—Our native species, the R. maximum and R. punctatum, according to Barton, possess properties similar to the R. chrysanthum, but milder. According to Bigelow, they are astringent, but not narcotic.
Rhododendron maximum, Linné, Rosebay tree, or Great laurel, is a tall, evergreen shrub, or small tree, found growing along mountainous streams in the eastern section of the United States. The leaves are very thick and leathery, entire, oblong, acute, smooth, and borne on short wrinkled stalks. The flowers appear in midsummer, and are very large and showy, in terminal, umbellate clusters. Tannin, gallic acid, wax, resin, albumen, a little essential oil, and several bodies peculiar to the Ericaceae—viz.: arbutin, ursone, ericolin, etc.—were found in the leaves by Kuehnel (Amer. Jour. Pharm., 1885, p. 164). Andromedotoxin was isolated by Plugge, in 1889. This agent was introduced to the profession by Dr. J. M. Mulholland, of Pennsylvania, in 1877, as a remedy for obstinate cough in elderly persons, in diphtheritic croup, and for the cure of those cutaneous affections in which arsenic is frequently prescribed, In cough, he found it more efficacious, when this was severe without expectoration, and was accompanied with a sweetish or mawkish odor of the breath, and a tremulous pulse. The dose is a teaspoonful every hour, of a mixture of 20 minims of the fluid extract with 4 fluid ounces of water.
Rhododendron ferrugineum, Linné, of Europe, has bitter, astringent leaves, which contain tannin as well as ericolin and arbutin. Said to contain no andromedotoxin (Dragendorff, Heilpflanzen).