Botanical Source.—Ambrosia trifida is a rough, hairy, herbaceous, annual plant, with an erect, branching, furrowed stem, from 5 to 10 feet in height. Its leaves are opposite, from 4 to 7 inches broad, scabrous and hairy, with three large, deep lobes which are oval, lanceolate, acuminate, and closely serrated; the lower leaves are often 5-lobed. The petioles are narrowly winged and ciliate; racemes often paniculate. The flowers are mean and obscure, in long, leafless spikes, axillary and terminal. The fruit (fertile involucre) is turbinate-obovoid, with a short, conical-pointed apex, 6-ribbed, the ribs terminating in as many cristate tubercles. It has a variety called Ambrosia trifida, var. integrifolia.
History.—This plant grows in low grounds and along streams, from Canada to Georgia, and west to Louisiana and Arkansas, bearing greenish-yellow flowers in August. It is much in use among farmers, for the "slabbers" in horses, effecting a cure in a few hours. It has a spicy, pleasant, aromatic taste, slightly resembling ginger, and imparts its properties to water. According to Rafinesque, the aborigines used it to make a sort of hemp and ropes.
Action, Medical Uses, and Dosage.—This plant is slightly stimulant, astringent, hemostatic, and antiseptic. Useful in decoction as an injection in leucorrhoea, prolapsus uteri, chronic gonorrhoea, and gleet; also valuable as a collyrium, in ophthalmia, and as a wash or gargle—with its internal use also—in nursing sore mouth. It will be found an excellent application to mercurial, and all other ulcers of a fetid or gangrenous character. As a remedy for mercurial salivation, used every half hour as a wash, it is said to be prompt and efficacious. Internally, the decoction is useful in fevers, attended with a disposition to putrescency, diarrhoea, and dysentery. It has been successfully employed in bleeding from the nose, and other hemorrhagic discharges, where the flow is small in amount. It has also been employed for the relief of after-pains, for hysteria and other nervous disorders. Dose of the decoction (tops ℥ss, aqua Oj) from 1 to 2 fluid ounces.
Related Species.—Ambrosia artemisiaefolia, Linné (Ambrosia elatior), Roman wormwood, or Ragweed, has a slender stem rising from 1 to 3 feet high, much branched, and pubescent when young; leaves opposite, the upper alternate, twice pinnatifid, smoothish above, paler or hoary beneath; barren flowers small, green, in terminal racemes, or spikes loosely panicled; fertile ones sessile about the axis of the upper leaves; fruit obovoid, or globular, pointed, armed with about 6 short acute teeth or spines (W.—G.). It is sometimes called "hog-weed," as but few animals excepting the hog will eat it. Cows occasionally partake of it, and it imparts to their milk a bitter taste which remains in butter made from the tainted cream. When carelessly gathered with wheat it also imparts to the flour of that cereal a bitter flavor, rendering it unfit for bread-making. Schimmel & Co., in 1894, isolated by distillation from the blooming plant, an essential oil, of deep-green color, and specific gravity 0.870. It has an aromatic, not unpleasant odor. Ambrosia trifida, subjected to the same process, did not yield any volatile oil. Ragweed is highly recommended as a fomentation in recent inflammation from wounds, or injuries of any kind. Made into a salve by bruising the green leaves, and simmering them in spirits and cream, it is very useful in hemorrhoidal tumors, and some forms of ulcer. It may be used as a tonic after intermittents, and to alleviate mucous fluxes. Dose: Specific ambrosia artemisiaefolia, 1 to 10 drops every 1 to 4 hours. Infusion (tops ℥ss, to aqua Oj), 1 to 2 fluid ounces. It is very common in all our fields, and would probably prove fully as efficacious if not more so, than A. trifida.
King's American Dispensatory, 1898, was written by Harvey Wickes Felter, M.D., and John Uri Lloyd, Phr. M., Ph. D.