This section is from the book "An Experimental History Of The Materia Medica", by William Lewis.
Petasites major & vulgaris C. B. Gale-rita & tuffilago major quibufdam. Tuffilago Peta-sites Linn. Butterbur or Pestilentwort: a perennial plant, found wild by the sides of ditches and in meadows; producing early in the spring a thick naked roundish stalk, with a spike of small naked purplish slofculous flowers on the top: the flowers and stalks soon wither, and are succeeded about May, by very large, roundish or somewhat heart-shaped leaves, (landing on long pedicles, somewhat hollowed in the middle so as to resemble a bonnet (petafos): the root is long, thick, of a dark brownish or black colour on the outside, and white within.
The roots of butterbur are recommended as aperient and alexipharmac; and promise, though now disregarded in practice, to be of consider-able activity. They have a strong smell, and a bitterish acrid taste, of the aromatic kind, but not agreeable, very durable and diffusive, scarcely to be concealed, as Fuller observes, by a large admixture of other substances. Their virtue appears to reside in a resinous matter; which is distinguishable by the eye in the dried root, and which is readily extracted by spirit of wine, petroleum: