Ascle'pias syri'aca, Common Milkweed, Silkweed. -- The root (rhizome), U.S.P. 1820-1850, 1870; United States. Herb 1-1.5 M. (3-5 degrees) high, stout, pubescent, finely soft; leaves oblong, 10-20 Cm. (4-8') long, downy beneath; flowers large, purplish-white, sweet-scented, hoods ovate with a tooth each side of stout, claw-like horn; fruit prickly pods containing much silky seed-down; root 2.5-15 Cm. (1-6') long, 6-12 Mm (1/4-1/2') thick, in sections, wrinkled, knotty, brownish; bark tough, thick, with laticiferous vessels, wood-wedges yellow, bitter, nauseous; contains asclepion (tasteless), bitter, crystalline principle, caoutchouc (6 p.c. of milk-juice), resin, tannin, starch. Used like preceding, also to coat over wounds, ulcers, etc., to promote cicatrization. Dose, gr. 15-40 (1-2.6 Gm.). A. curassav'ica, Bastard Ipecacuanha, C. and S. America; flowers bright red; the glossy seed-hairs, called vegetable silk, firmer than the preceding; contains asclepiadin; used natively as we do.