Erig'eron canaden'sis, Canada Fleabane, Horseweed, Fireweed. -- The herb, U.S.P. 1820-1870; the volatile oil distilled from the fresh flowering herb, U.S.P. 1860-1900; N. America, fields, waste places; naturalized in other countries. Annual herb, .3-2.5 M. (1-8 degrees) high; stem branching, hairy, furrowed; leaves linear-lanceolate, entire, dentate; flowers small, numerous, white, terminal panicles; contains volatile oil .2-.4 p.c., bitter principle (amaroid), tannin, gallic acid. Oil is a pale yellow liquid, darker and thicker with age and exposure; odor peculiar, aromatic, persistent; taste aromatic, pungent, sp. gr. 0.850; contains d-limonene, CH, terpinol, a substance easily decomposed or polymerized by heat making distillation difficult at ordinary pressure.  Test: 1. Soluble in equal volume of alcohol (dist. From oil of fireweed, Erechthi'tes hieracifo'lia, and oil of turpentine), also in equal volume of glacial acetic acid, which solution with bromine yields crystals of CHBr.  Stimulant, tonic, diuretic, diaphoretic, styptic; diarrhea, dysentery, gravel, dropsy, hemorrhages of uterus and bowels; similar to oil of turpentine, but less irritating and stimulating.  First employed by the "eclectics."  Should be kept cool, dark, in well-stoppered, amber-colored bottles.  Dose, gr. 15-60 (1-4Gm.); decoction, 5 p.c. 3ss-1 (15-30 cc.); oil, mv-10 (.3-.6 cc.).  E. An'nuus (heterophyl'lus), Various-leaved Fleabane, Sweet Scabious; the herb, U.S.P. 1830-1860.  Biennial herb, 1-1.5 M. (3.5 degrees) high, branched, hairy, leaves sharply, coarsely toothed; flowers Aug., corymbs, rays white tinged with purple, disk yellow; in fields, waste places.  E. Philadel'phicus, Philadelphia Fleabane; the herb, U.S.P. 1820-1850.  Perennial herb, .3-1 M. (1-3 degrees) high, pubescent, slender, leafy; leaves 5-10 Cm. (2-4') long, 12-18 Mm. (1/2-3/4') wide, midrib broad, flowers June-Aug., numerous, panicled corymbs, rays 150-200, filiform purplish, disk yellow.  Both have same constituents and properties as E. Canadensis.