Treacle mustard or Treacle water

(Bot.), a cruciferous plant of several species of the genus Erysimum, found in Europe and North America;—so called because one species (E. cheiranthoides) was formerly used as an ingredient in Venice treacle, or theriaca. Baird.—Treacle water, a compound cordial, formerly much esteemed, and prepared in different ways from a variety of ingredients, as hartshorn, roots of various plants, flowers, juices of plants, wines, &c., distilled or digested with Venice treacle. It was regarded as a medicine of great virtue. Næres.