Botanical name: 

The root of Hydrangea arborescens, Linné (Nat. Ord. Saxifragaceae). A handsome shrub along streams and in damp, rocky situations in the southern and middle-west states of this country. Dose, 5 to 60 grains.
Common Names: Wild Hydrangea, Seven Barks.

Principal Consitituents.—The glucoside hydrangin (C34H25O11), saponin, resins, and fixed and volatile oils.
Preparation.—Specific Medicine Hydrangea. Dose, 5 to 60 drops.
Specific Indications.—Vesical and urethral irritation, with gravel; difficult urination; deep-seated renal pain; bloody urine; irritation of the bronchial membranes.

Action and Therapy.—Hydrangea is diuretic and sedative to cystic and urethral irritation, with passage of gravelly urine. It does not dissolve gravel, but is believed to be of value in preventing their formation, especially alkaline and phosphatic concretions. It should be administered in hot water. Hydrangea may be used in any renal disorder with dysuria, blood in the urine, or deep-seated pain in the region of the kidneys. It is not contraindicated by inflammation and may be employed with safety in acute nephritis. It is especially serviceable in alkaline urine and in bladder irritation of the aged with tendency to catarrh. Unquestionably hydrangea has a kindly action upon the mucosa of the urinary organs and it has alterative properties making it useful in strumous diseases.

The Eclectic Materia Medica, Pharmacology and Therapeutics, 1922, was written by Harvey Wickes Felter, M.D.