Ambrosia. Ambrosia trifida, L. Ragweed, Roman Wormwood, Hog-weed, Bitter-weed, Ambrosie, Fr. Traubenkraut, G. (Fam. Compositae.)—This and another indigenous annual, A. artemisiifolia L., are deemed by the eclectics astringent and stimulant, and are given in low forms of fever. L. W. Schwab has found in A. artemisiifolia a bitter glucoside (A. J. P., 1890), and Schimmel & Co. have obtained from it about 0.15 per cent. of a green volatile oil (sp. gr. 0.876). (Schim. Rep., 1904, p. 96.) The pollen of this plant is also said to be one of the causes of hay fever. It is estimated that there are about 90,000,000 pollen grains in a gramme of ragweed pollen.