Allium Cepa.—Onion.

Photo: Allium cepa 4. Related plant: Allium (U. S. P.)—Garlic

The bulb of the Allium Cepa, Linné.
Nat. Ord.—Liliaceae.

Botanical Source.—The common onion is a biennial garden plant, having a scape, which appears the second year, 2 to 4 feet high, being naked, smooth, straight, stout, swollen at the base, and fistulous, bearing at the top a round umbel of greenish-white flowers. The leaves are round and fistulous, of a shining green color, acute, and shorter than the stem. The part employed is the bulb.

Description.—The onion is a tunicated bulb, compressed or round, or oblong in figure, invested with a shining, thin, dry membrane, of a reddish or white color. It is less pungent to the taste than garlic, with some degree of sweetness, and a peculiar, well-known odor. Onion bulbs are of various shapes and sizes, usually globular, the layers being juicy.

History and Chemical Composition.—This biennial plant is supposed to be a native of Hungary, but is now found in all parts of the world. According to Fourcroy and Vauquelin, onion contains an acrid, volatile oil, uncrystallizable sugar, gum, albumen, woody fiber, acetic and phosphoric acids, phosphate and citrate of calcium, and water. The oil is colorless, acrid, and contains sulphur. It was investigated, in 1892, by Semmler, who found it to be mainly composed of a sulphur compound, C6H12S2. A peculiar wine may be made by fermenting the juice of the onion.

Action and Medical Uses.—Onion possesses properties allied to those of garlic, but in a milder degree, and the absorption of its oil and influence upon the system is somewhat similar to that of the oil of garlic. Onions do not agree with all persons, especially dyspeptics, in whom they favor the production of flatus, which, however, is a common symptom among all those who eat largely of them; boiling, in a great measure, deprives them of this property. Sugar and onion-juice form a syrup, much used in domestic practice, for cough and other affections of the air-tubes among children. A roasted onion employed as a cataplasm to suppurating tumors, or to the ear in otitis, has proved beneficial. A saturated tincture of onions made with good Holland gin, has been found serviceable in gravel and dropsical affections. A cataplasm of onions pounded with vinegar, applied for a number of days, and changed 3 times a day, has been found to cure corns and bunions.

Photo: Allium schoenoprasum 4. Related Species.Allium Porrum, Linné. The Common leek. Allium Schoenoprasum, Linné. The Chives. Allium Ascalonicum, Linné. The Shallot. The above species possess similar medicinal qualities, though less active. They have the characteristic odor, though milder, and are cultivated in gardens for the same purpose as the onion.

King's American Dispensatory, 1898, was written by Harvey Wickes Felter, M.D., and John Uri Lloyd, Phr. M., Ph. D.