WHITE SNAKEROOT, Eupatorium
rugosum Houtt. 1, upper part of plant; 2, root; 3,
flower head; 4, single flower; 5, seed. Perennial,
spreading by seeds and short rhizomes. Roots much branched and fibrous.
Stem 1 to 3 feet (30 to 90 cm) tall, smooth, and branched near top.
Leaves opposite, elliptical, thin, smooth, with toothed edges and
slender petioles. Flower heads small, of white disk flowers
only. Seed black, angular, about 1/8 inch (3 mm) long, with a tuft
of white hairs. Found in hardwood timber areas, woodland, pastures,
and waste places. It grows only in shaded areas. Contains a cumulative
poison that causes the disease known as "trembles" in cattle and horses.
Dairy products from animals that have eaten the plant are poisonous to
man, causing "milk sickness," one of the serious scourges of pioneers in