Smallanthus uvedalius
Botanicals.com says: Of great use applied externally in stimulating the growth of the hair, and is an ingredient of many American hair ointments and lotions. A snake-oil salesman claimed that it was the best hair tonic in the materia medica, in the proportions of four ounces of the tincture with twelve ounces of bay rum, to be rubbed thoroughly into the scalp. A good combination would be castor oil three parts, glycerine one part, lanolin three parts, extract uvedalia two parts, melted and rubbed together and cooled. This should be rubbed thoroughly into the roots of the hair.