Stone Root, Horse-Balm, Collinsonia Canadensis. Not official. Belongs to the mint family. The leaves contain a volatile oil. The root is the part principally used, and its constituents have not been determined. The U. S. Department of Agriculture has investigated Horsemint, which is allied to collinsonia, and finds it to contain very considerable quantities of thymol, or a phenol from which thymol may be extracted. The collinsonia root is exceedingly hard, has a disagreeable balsamic odor, and loses its activity by drying or exposure to heat; hence it must be extracted by slow maceration or the preparation is inert. It possesses the stimulant properties common to plants of its class, and is said to be diuretic and tonic. John V. Shoemaker considered it an antispasmodic of value in gastralgia. In appreciable doses it is emetic.

Doses short of nausea (fl., 15 minims) relieve tense and spasmodic throat troubles, such as aphonia from over-use of the voice. It is a good bitter in smaller doses (fl., 5 to 10 minims), and it has an apparently well justified reputation in relieving spasm and irritation of the rectal tissues from hemorrhoids or other cause.