Botanical name: 

The bark of the root of Ptelea trifoliata, Linné (Nat. Ord. Rutaceae). A common shrub of the United States, especially west of the Alleghenies. Dose, 5 to 30 grains.
Common Names: Wafer Ash, Shrubby Trefoil, Wing Seed, Hop Tree.

Principal Constituents.—Resins, a volatile oil, a berberine-like bitter, and arginine (C6H14N4O2).
Preparation.—Specific Medicine Ptelea. Dose, 1 to 30 drops.
Specific Indications.—Asthmatic dyspnea; chronic diseases with constriction of chest and short breathing.

Action and Therapy.—Ptelea is regarded by some as second only to hydrastis as a tonic. It acts as a sedative to irritated membranes, and is said to be tolerated by the stomach when other tonics might aggravate. The field in which it has been mostly used is in convalescence from fevers, debility resulting from gastro-intestinal irritation, and in asthmatic seizures accompanied by a sense of constriction in the thorax.

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